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itemprop=name><meta content="执行细节 首先设置了默认的languageDriver org/mybatis/mybatis/3.5.11/mybatis-3.5.11-sources.jar!" itemprop=description></span><header class=post-header><h1 itemprop="name headline" class=post-title>mybatis系列-第一条sql的更多细节</h1><div class=post-meta-container><div class=post-meta><span class=post-meta-item><span class=post-meta-item-icon><i class="far fa-calendar"></i> </span><span class=post-meta-item-text>发表于</span> <time itemprop="dateCreated datePublished" title="创建时间:2022-12-18 21:42:38" datetime=2022-12-18T21:42:38+08:00>2022-12-18</time> </span><span class=post-meta-item><span class=post-meta-item-icon><i class="far fa-folder"></i> </span><span class=post-meta-item-text>分类于</span> <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Java/ itemprop=url rel=index><span itemprop=name>Java</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Java/Mybatis/ itemprop=url rel=index><span itemprop=name>Mybatis</span></a> </span></span><span class="post-meta-item cloudflare-page-counter" data-increment=true data-path=/2022/12/18/mybatis%E7%B3%BB%E5%88%97-%E7%AC%AC%E4%B8%80%E6%9D%A1sql%E7%9A%84%E6%9B%B4%E5%A4%9A%E7%BB%86%E8%8A%82/ data-title=mybatis系列-第一条sql的更多细节 title=阅读次数><span class=post-meta-item-icon><i class="far fa-eye"></i> </span><span class=post-meta-item-text>阅读次数:</span> <span class=cloudflare-page-counter-count></span></span></div><div class=post-description>执行细节 首先设置了默认的languageDriver org/mybatis/mybatis/3.5.11/mybatis-3.5.11-sources.jar!</div></div></header><div class=post-body itemprop=articleBody><p>执行细节<br>首先设置了默认的<code>languageDriver</code><br><code>org/mybatis/mybatis/3.5.11/mybatis-3.5.11-sources.jar!/org/apache/ibatis/session/Configuration.java:215</code><br>在<code>configuration</code>的构造方法里<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br></pre><td class=code><pre><span class=line>languageRegistry.setDefaultDriverClass(XMLLanguageDriver.class);</span><br></pre></table></figure><p>而在<br><code>org.apache.ibatis.builder.xml.XMLStatementBuilder#parseStatementNode</code><br>中,创建了<code>sqlSource</code>,这里就会根据前面的 <code>LanguageDriver</code> 的实现选择对应的 <code>sqlSource</code> ,<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br></pre><td class=code><pre><span class=line><span class=type>SqlSource</span> <span class=variable>sqlSource</span> <span class=operator>=</span> langDriver.createSqlSource(configuration, context, parameterTypeClass);</span><br></pre></table></figure><p><code>createSqlSource</code> 就会调用<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> SqlSource <span class="title function_">createSqlSource</span><span class=params>(Configuration configuration, XNode script, Class<?> parameterType)</span> {</span><br><span class=line> <span class=type>XMLScriptBuilder</span> <span class=variable>builder</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">XMLScriptBuilder</span>(configuration, script, parameterType);</span><br><span class=line> <span class=keyword>return</span> builder.parseScriptNode();</span><br><span class=line>}</span><br></pre></table></figure><p>再往下的逻辑在 <code>parseScriptNode</code> 中,<code>org.apache.ibatis.scripting.xmltags.XMLScriptBuilder#parseScriptNode</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> SqlSource <span class="title function_">parseScriptNode</span><span class=params>()</span> {</span><br><span class=line> <span class=type>MixedSqlNode</span> <span class=variable>rootSqlNode</span> <span class=operator>=</span> parseDynamicTags(context);</span><br><span class=line> SqlSource sqlSource;</span><br><span class=line> <span class=keyword>if</span> (isDynamic) {</span><br><span class=line> sqlSource = <span class=keyword>new</span> <span class="title class_">DynamicSqlSource</span>(configuration, rootSqlNode);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> sqlSource = <span class=keyword>new</span> <span class="title class_">RawSqlSource</span>(configuration, rootSqlNode, parameterType);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> sqlSource;</span><br><span class=line>}</span><br></pre></table></figure><p>首先要解析<code>dynamicTag</code>,调用了<code>org.apache.ibatis.scripting.xmltags.XMLScriptBuilder#parseDynamicTags</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br></pre><td class=code><pre><span class=line><span class=keyword>protected</span> MixedSqlNode <span class="title function_">parseDynamicTags</span><span class=params>(XNode node)</span> {</span><br><span class=line> List<SqlNode> contents = <span class=keyword>new</span> <span class="title class_">ArrayList</span><>();</span><br><span class=line> <span class=type>NodeList</span> <span class=variable>children</span> <span class=operator>=</span> node.getNode().getChildNodes();</span><br><span class=line> <span class=keyword>for</span> (<span class=type>int</span> <span class=variable>i</span> <span class=operator>=</span> <span class=number>0</span>; i < children.getLength(); i++) {</span><br><span class=line> <span class=type>XNode</span> <span class=variable>child</span> <span class=operator>=</span> node.newXNode(children.item(i));</span><br><span class=line> <span class=keyword>if</span> (child.getNode().getNodeType() == Node.CDATA_SECTION_NODE || child.getNode().getNodeType() == Node.TEXT_NODE) {</span><br><span class=line> <span class=type>String</span> <span class=variable>data</span> <span class=operator>=</span> child.getStringBody(<span class=string>""</span>);</span><br><span class=line> <span class=type>TextSqlNode</span> <span class=variable>textSqlNode</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">TextSqlNode</span>(data);</span><br><span class=line> <span class=comment>// ---------> 主要是这边的逻辑</span></span><br><span class=line> <span class=keyword>if</span> (textSqlNode.isDynamic()) {</span><br><span class=line> contents.add(textSqlNode);</span><br><span class=line> isDynamic = <span class=literal>true</span>;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> contents.add(<span class=keyword>new</span> <span class="title class_">StaticTextSqlNode</span>(data));</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> <span class=keyword>if</span> (child.getNode().getNodeType() == Node.ELEMENT_NODE) { <span class=comment>// issue #628</span></span><br><span class=line> <span class=type>String</span> <span class=variable>nodeName</span> <span class=operator>=</span> child.getNode().getNodeName();</span><br><span class=line> <span class=type>NodeHandler</span> <span class=variable>handler</span> <span class=operator>=</span> nodeHandlerMap.get(nodeName);</span><br><span class=line> <span class=keyword>if</span> (handler == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">BuilderException</span>(<span class=string>"Unknown element <"</span> + nodeName + <span class=string>"> in SQL statement."</span>);</span><br><span class=line> }</span><br><span class=line> handler.handleNode(child, contents);</span><br><span class=line> isDynamic = <span class=literal>true</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> <span class=keyword>new</span> <span class="title class_">MixedSqlNode</span>(contents);</span><br><span class=line> }</span><br></pre></table></figure><p>判断是否是动态<code>sql</code>,调用了<code>org.apache.ibatis.scripting.xmltags.TextSqlNode#isDynamic</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=type>boolean</span> <span class="title function_">isDynamic</span><span class=params>()</span> {</span><br><span class=line> <span class=type>DynamicCheckerTokenParser</span> <span class=variable>checker</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">DynamicCheckerTokenParser</span>();</span><br><span class=line> <span class=comment>// ----------> 主要是这里的方法</span></span><br><span class=line> <span class=type>GenericTokenParser</span> <span class=variable>parser</span> <span class=operator>=</span> createParser(checker);</span><br><span class=line> parser.parse(text);</span><br><span class=line> <span class=keyword>return</span> checker.isDynamic();</span><br><span class=line>}</span><br></pre></table></figure><p>创建<code>parser</code>的时候可以看到这个<code>parser</code>是干了啥,其实就是找有没有<code>${</code> , <code>}</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> GenericTokenParser <span class="title function_">createParser</span><span class=params>(TokenHandler handler)</span> {</span><br><span class=line> <span class=keyword>return</span> <span class=keyword>new</span> <span class="title class_">GenericTokenParser</span>(<span class=string>"${"</span>, <span class=string>"}"</span>, handler);</span><br><span class=line>}</span><br></pre></table></figure><p>如果是的话,就在上面把 <code>isDynamic</code> 设置为<code>true</code> 如果是<code>true</code> 的话就创建 <code>DynamicSqlSource</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br></pre><td class=code><pre><span class=line>sqlSource = <span class=keyword>new</span> <span class="title class_">DynamicSqlSource</span>(configuration, rootSqlNode);</span><br></pre></table></figure><p>如果不是的话就创建<code>RawSqlSource</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br></pre><td class=code><pre><span class=line>sqlSource = <span class=keyword>new</span> <span class="title class_">RawSqlSource</span>(configuration, rootSqlNode, parameterType);</span><br><span class=line>```java</span><br><span class=line></span><br><span class=line>但是这不是一个真实可用的 `sqlSource` ,</span><br><span class=line>实际创建的时候会走到这</span><br><span class=line>```java</span><br><span class=line><span class=keyword>public</span> <span class="title function_">RawSqlSource</span><span class=params>(Configuration configuration, SqlNode rootSqlNode, Class<?> parameterType)</span> {</span><br><span class=line> <span class=built_in>this</span>(configuration, getSql(configuration, rootSqlNode), parameterType);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>public</span> <span class="title function_">RawSqlSource</span><span class=params>(Configuration configuration, String sql, Class<?> parameterType)</span> {</span><br><span class=line> <span class=type>SqlSourceBuilder</span> <span class=variable>sqlSourceParser</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">SqlSourceBuilder</span>(configuration);</span><br><span class=line> Class<?> clazz = parameterType == <span class=literal>null</span> ? Object.class : parameterType;</span><br><span class=line> sqlSource = sqlSourceParser.parse(sql, clazz, <span class=keyword>new</span> <span class="title class_">HashMap</span><>());</span><br><span class=line> }</span><br></pre></table></figure><p>具体的<code>sqlSource</code>是通过<code>org.apache.ibatis.builder.SqlSourceBuilder#parse</code> 创建的<br>具体的代码逻辑是<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> SqlSource <span class="title function_">parse</span><span class=params>(String originalSql, Class<?> parameterType, Map<String, Object> additionalParameters)</span> {</span><br><span class=line> <span class=type>ParameterMappingTokenHandler</span> <span class=variable>handler</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">ParameterMappingTokenHandler</span>(configuration, parameterType, additionalParameters);</span><br><span class=line> <span class=type>GenericTokenParser</span> <span class=variable>parser</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">GenericTokenParser</span>(<span class=string>"#{"</span>, <span class=string>"}"</span>, handler);</span><br><span class=line> String sql;</span><br><span class=line> <span class=keyword>if</span> (configuration.isShrinkWhitespacesInSql()) {</span><br><span class=line> sql = parser.parse(removeExtraWhitespaces(originalSql));</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> sql = parser.parse(originalSql);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> <span class=keyword>new</span> <span class="title class_">StaticSqlSource</span>(configuration, sql, handler.getParameterMappings());</span><br><span class=line>}</span><br></pre></table></figure><p>这里创建的其实是<code>StaticSqlSource</code> ,多带一句前面的<code>parser</code>是将原来这样<code>select * from student where id = #{id}</code> 的 <code>sql</code> 解析成了<code>select * from student where id = ?</code> 然后创建了<code>StaticSqlSource</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class="title function_">StaticSqlSource</span><span class=params>(Configuration configuration, String sql, List<ParameterMapping> parameterMappings)</span> {</span><br><span class=line> <span class=built_in>this</span>.sql = sql;</span><br><span class=line> <span class=built_in>this</span>.parameterMappings = parameterMappings;</span><br><span class=line> <span class=built_in>this</span>.configuration = configuration;</span><br><span class=line>}</span><br></pre></table></figure><p>为什么前面要讲这么多好像没什么关系的代码呢,其实在最开始我们执行<code>sql</code>的代码中<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> <E> List<E> <span class="title function_">query</span><span class=params>(MappedStatement ms, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>BoundSql</span> <span class=variable>boundSql</span> <span class=operator>=</span> ms.getBoundSql(parameterObject);</span><br><span class=line> <span class=type>CacheKey</span> <span class=variable>key</span> <span class=operator>=</span> createCacheKey(ms, parameterObject, rowBounds, boundSql);</span><br><span class=line> <span class=keyword>return</span> query(ms, parameterObject, rowBounds, resultHandler, key, boundSql);</span><br><span class=line> }</span><br></pre></table></figure><p>这里获取了<code>BoundSql</code>,而<code>BoundSql</code>是怎么来的呢,首先调用了<code>org.apache.ibatis.mapping.MappedStatement#getBoundSql</code><figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> BoundSql <span class="title function_">getBoundSql</span><span class=params>(Object parameterObject)</span> {</span><br><span class=line> <span class=type>BoundSql</span> <span class=variable>boundSql</span> <span class=operator>=</span> sqlSource.getBoundSql(parameterObject);</span><br><span class=line> List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();</span><br><span class=line> <span class=keyword>if</span> (parameterMappings == <span class=literal>null</span> || parameterMappings.isEmpty()) {</span><br><span class=line> boundSql = <span class=keyword>new</span> <span class="title class_">BoundSql</span>(configuration, boundSql.getSql(), parameterMap.getParameterMappings(), parameterObject);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// check for nested result maps in parameter mappings (issue #30)</span></span><br><span class=line> <span class=keyword>for</span> (ParameterMapping pm : boundSql.getParameterMappings()) {</span><br><span class=line> <span class=type>String</span> <span class=variable>rmId</span> <span class=operator>=</span> pm.getResultMapId();</span><br><span class=line> <span class=keyword>if</span> (rmId != <span class=literal>null</span>) {</span><br><span class=line> <span class=type>ResultMap</span> <span class=variable>rm</span> <span class=operator>=</span> configuration.getResultMap(rmId);</span><br><span class=line> <span class=keyword>if</span> (rm != <span class=literal>null</span>) {</span><br><span class=line> hasNestedResultMaps |= rm.hasNestedResultMaps();</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> boundSql;</span><br><span class=line> }</span><br></pre></table></figure><p>而我们从上面的解析中可以看到这里的<code>sqlSource</code>是一层<code>RawSqlSource</code> , 它的<code>getBoundSql</code>又是调用内部的<code>sqlSource</code>的方法<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> BoundSql <span class="title function_">getBoundSql</span><span class=params>(Object parameterObject)</span> {</span><br><span class=line> <span class=keyword>return</span> sqlSource.getBoundSql(parameterObject);</span><br><span class=line>}</span><br></pre></table></figure><p>内部的<code>sqlSource</code> 就是<code>StaticSqlSource</code> ,<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> BoundSql <span class="title function_">getBoundSql</span><span class=params>(Object parameterObject)</span> {</span><br><span class=line> <span class=keyword>return</span> <span class=keyword>new</span> <span class="title class_">BoundSql</span>(configuration, sql, parameterMappings, parameterObject);</span><br><span class=line>}</span><br></pre></table></figure><p>这个<code>BoundSql</code>的内容也比较简单<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class="title function_">BoundSql</span><span class=params>(Configuration configuration, String sql, List<ParameterMapping> parameterMappings, Object parameterObject)</span> {</span><br><span class=line> <span class=built_in>this</span>.sql = sql;</span><br><span class=line> <span class=built_in>this</span>.parameterMappings = parameterMappings;</span><br><span class=line> <span class=built_in>this</span>.parameterObject = parameterObject;</span><br><span class=line> <span class=built_in>this</span>.additionalParameters = <span class=keyword>new</span> <span class="title class_">HashMap</span><>();</span><br><span class=line> <span class=built_in>this</span>.metaParameters = configuration.newMetaObject(additionalParameters);</span><br><span class=line>}</span><br></pre></table></figure><p>而上次在这边<code>org.apache.ibatis.executor.SimpleExecutor#doQuery</code> 的时候落了个东西,就是<code>StatementHandler</code>的逻辑<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> <E> List<E> <span class="title function_">doQuery</span><span class=params>(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>Statement</span> <span class=variable>stmt</span> <span class=operator>=</span> <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=type>Configuration</span> <span class=variable>configuration</span> <span class=operator>=</span> ms.getConfiguration();</span><br><span class=line> <span class=type>StatementHandler</span> <span class=variable>handler</span> <span class=operator>=</span> configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);</span><br><span class=line> stmt = prepareStatement(handler, ms.getStatementLog());</span><br><span class=line> <span class=keyword>return</span> handler.query(stmt, resultHandler);</span><br><span class=line> } <span class=keyword>finally</span> {</span><br><span class=line> closeStatement(stmt);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>它是通过statementType来区分应该使用哪个statementHandler,我们这使用的就是PreparedStatementHandler<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class="title function_">RoutingStatementHandler</span><span class=params>(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql)</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>switch</span> (ms.getStatementType()) {</span><br><span class=line> <span class=keyword>case</span> STATEMENT:</span><br><span class=line> delegate = <span class=keyword>new</span> <span class="title class_">SimpleStatementHandler</span>(executor, ms, parameter, rowBounds, resultHandler, boundSql);</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> PREPARED:</span><br><span class=line> delegate = <span class=keyword>new</span> <span class="title class_">PreparedStatementHandler</span>(executor, ms, parameter, rowBounds, resultHandler, boundSql);</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>case</span> CALLABLE:</span><br><span class=line> delegate = <span class=keyword>new</span> <span class="title class_">CallableStatementHandler</span>(executor, ms, parameter, rowBounds, resultHandler, boundSql);</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">ExecutorException</span>(<span class=string>"Unknown statement type: "</span> + ms.getStatementType());</span><br><span class=line> }</span><br><span class=line></span><br><span class=line>}</span><br></pre></table></figure><p>所以上次有个细节可以补充,这边的doQuery里面的handler.query 应该是调用了PreparedStatementHandler 的query方法<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> <E> List<E> <span class="title function_">doQuery</span><span class=params>(MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>Statement</span> <span class=variable>stmt</span> <span class=operator>=</span> <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=type>Configuration</span> <span class=variable>configuration</span> <span class=operator>=</span> ms.getConfiguration();</span><br><span class=line> <span class=type>StatementHandler</span> <span class=variable>handler</span> <span class=operator>=</span> configuration.newStatementHandler(wrapper, ms, parameter, rowBounds, resultHandler, boundSql);</span><br><span class=line> stmt = prepareStatement(handler, ms.getStatementLog());</span><br><span class=line> <span class=keyword>return</span> handler.query(stmt, resultHandler);</span><br><span class=line> } <span class=keyword>finally</span> {</span><br><span class=line> closeStatement(stmt);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>因为上面prepareStatement中getConnection拿到connection是com.mysql.cj.jdbc.ConnectionImpl#ConnectionImpl(com.mysql.cj.conf.HostInfo)<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> <E> List<E> <span class="title function_">query</span><span class=params>(Statement statement, ResultHandler resultHandler)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>PreparedStatement</span> <span class=variable>ps</span> <span class=operator>=</span> (PreparedStatement) statement;</span><br><span class=line> ps.execute();</span><br><span class=line> <span class=keyword>return</span> resultSetHandler.handleResultSets(ps);</span><br><span class=line>}</span><br></pre></table></figure><p>那又为什么是这个呢,可以在网上找,我们在mybatis-config.xml里配置的<figure class="highlight xml"><table><tr><td class=gutter><pre><span class=line>1</span><br></pre><td class=code><pre><span class=line><span class=tag><<span class=name>transactionManager</span> <span class=attr>type</span>=<span class=string>"JDBC"</span>/></span></span><br></pre></table></figure><p>因此在parseConfiguration中配置environment时<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=keyword>void</span> <span class="title function_">parseConfiguration</span><span class=params>(XNode root)</span> {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=comment>// issue #117 read properties first</span></span><br><span class=line> propertiesElement(root.evalNode(<span class=string>"properties"</span>));</span><br><span class=line> <span class=type>Properties</span> <span class=variable>settings</span> <span class=operator>=</span> settingsAsProperties(root.evalNode(<span class=string>"settings"</span>));</span><br><span class=line> loadCustomVfs(settings);</span><br><span class=line> loadCustomLogImpl(settings);</span><br><span class=line> typeAliasesElement(root.evalNode(<span class=string>"typeAliases"</span>));</span><br><span class=line> pluginElement(root.evalNode(<span class=string>"plugins"</span>));</span><br><span class=line> objectFactoryElement(root.evalNode(<span class=string>"objectFactory"</span>));</span><br><span class=line> objectWrapperFactoryElement(root.evalNode(<span class=string>"objectWrapperFactory"</span>));</span><br><span class=line> reflectorFactoryElement(root.evalNode(<span class=string>"reflectorFactory"</span>));</span><br><span class=line> settingsElement(settings);</span><br><span class=line> <span class=comment>// read it after objectFactory and objectWrapperFactory issue #631</span></span><br><span class=line> <span class=comment>// ----------> 就是这里</span></span><br><span class=line> environmentsElement(root.evalNode(<span class=string>"environments"</span>));</span><br><span class=line> databaseIdProviderElement(root.evalNode(<span class=string>"databaseIdProvider"</span>));</span><br><span class=line> typeHandlerElement(root.evalNode(<span class=string>"typeHandlers"</span>));</span><br><span class=line> mapperElement(root.evalNode(<span class=string>"mappers"</span>));</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">BuilderException</span>(<span class=string>"Error parsing SQL Mapper Configuration. Cause: "</span> + e, e);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>调用的这个方法通过获取xml中的transactionManager 配置的类型,也就是JDBC<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=keyword>void</span> <span class="title function_">environmentsElement</span><span class=params>(XNode context)</span> <span class=keyword>throws</span> Exception {</span><br><span class=line> <span class=keyword>if</span> (context != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>if</span> (environment == <span class=literal>null</span>) {</span><br><span class=line> environment = context.getStringAttribute(<span class=string>"default"</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>for</span> (XNode child : context.getChildren()) {</span><br><span class=line> <span class=type>String</span> <span class=variable>id</span> <span class=operator>=</span> child.getStringAttribute(<span class=string>"id"</span>);</span><br><span class=line> <span class=keyword>if</span> (isSpecifiedEnvironment(id)) {</span><br><span class=line> <span class=comment>// -------> 找到这里</span></span><br><span class=line> <span class=type>TransactionFactory</span> <span class=variable>txFactory</span> <span class=operator>=</span> transactionManagerElement(child.evalNode(<span class=string>"transactionManager"</span>));</span><br><span class=line> <span class=type>DataSourceFactory</span> <span class=variable>dsFactory</span> <span class=operator>=</span> dataSourceElement(child.evalNode(<span class=string>"dataSource"</span>));</span><br><span class=line> <span class=type>DataSource</span> <span class=variable>dataSource</span> <span class=operator>=</span> dsFactory.getDataSource();</span><br><span class=line> Environment.<span class=type>Builder</span> <span class=variable>environmentBuilder</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">Environment</span>.Builder(id)</span><br><span class=line> .transactionFactory(txFactory)</span><br><span class=line> .dataSource(dataSource);</span><br><span class=line> configuration.setEnvironment(environmentBuilder.build());</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>是通过以下方法获取的,<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br></pre><td class=code><pre><span class=line><span class=comment>// 方法全限定名 org.apache.ibatis.builder.xml.XMLConfigBuilder#transactionManagerElement</span></span><br><span class=line><span class=keyword>private</span> TransactionFactory <span class="title function_">transactionManagerElement</span><span class=params>(XNode context)</span> <span class=keyword>throws</span> Exception {</span><br><span class=line> <span class=keyword>if</span> (context != <span class=literal>null</span>) {</span><br><span class=line> <span class=type>String</span> <span class=variable>type</span> <span class=operator>=</span> context.getStringAttribute(<span class=string>"type"</span>);</span><br><span class=line> <span class=type>Properties</span> <span class=variable>props</span> <span class=operator>=</span> context.getChildrenAsProperties();</span><br><span class=line> <span class=type>TransactionFactory</span> <span class=variable>factory</span> <span class=operator>=</span> (TransactionFactory) resolveClass(type).getDeclaredConstructor().newInstance();</span><br><span class=line> factory.setProperties(props);</span><br><span class=line> <span class=keyword>return</span> factory;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">BuilderException</span>(<span class=string>"Environment declaration requires a TransactionFactory."</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line><span class=comment>// 方法全限定名 org.apache.ibatis.builder.BaseBuilder#resolveClass</span></span><br><span class=line><span class=keyword>protected</span> <T> Class<? <span class=keyword>extends</span> <span class="title class_">T</span>> resolveClass(String alias) {</span><br><span class=line> <span class=keyword>if</span> (alias == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>return</span> resolveAlias(alias);</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">BuilderException</span>(<span class=string>"Error resolving class. Cause: "</span> + e, e);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line><span class=comment>// 方法全限定名 org.apache.ibatis.builder.BaseBuilder#resolveAlias</span></span><br><span class=line> <span class=keyword>protected</span> <T> Class<? <span class=keyword>extends</span> <span class="title class_">T</span>> resolveAlias(String alias) {</span><br><span class=line> <span class=keyword>return</span> typeAliasRegistry.resolveAlias(alias);</span><br><span class=line> }</span><br><span class=line><span class=comment>// 方法全限定名 org.apache.ibatis.type.TypeAliasRegistry#resolveAlias</span></span><br><span class=line> <span class=keyword>public</span> <T> Class<T> <span class="title function_">resolveAlias</span><span class=params>(String string)</span> {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>if</span> (string == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> }</span><br><span class=line> <span class=comment>// issue #748</span></span><br><span class=line> <span class=type>String</span> <span class=variable>key</span> <span class=operator>=</span> string.toLowerCase(Locale.ENGLISH);</span><br><span class=line> Class<T> value;</span><br><span class=line> <span class=keyword>if</span> (typeAliases.containsKey(key)) {</span><br><span class=line> value = (Class<T>) typeAliases.get(key);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> value = (Class<T>) Resources.classForName(string);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> value;</span><br><span class=line> } <span class=keyword>catch</span> (ClassNotFoundException e) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">TypeException</span>(<span class=string>"Could not resolve type alias '"</span> + string + <span class=string>"'. Cause: "</span> + e, e);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>而通过JDBC获取得是啥的,就是在Configuration的构造方法里写了的JdbcTransactionFactory<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class="title function_">Configuration</span><span class=params>()</span> {</span><br><span class=line> typeAliasRegistry.registerAlias(<span class=string>"JDBC"</span>, JdbcTransactionFactory.class);</span><br></pre></table></figure><p>所以我们在这<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br></pre><td class=code><pre><span class=line><span class=keyword>private</span> SqlSession <span class="title function_">openSessionFromDataSource</span><span class=params>(ExecutorType execType, TransactionIsolationLevel level, <span class=type>boolean</span> autoCommit)</span> {</span><br><span class=line> <span class=type>Transaction</span> <span class=variable>tx</span> <span class=operator>=</span> <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>final</span> <span class=type>Environment</span> <span class=variable>environment</span> <span class=operator>=</span> configuration.getEnvironment();</span><br><span class=line> <span class=keyword>final</span> <span class=type>TransactionFactory</span> <span class=variable>transactionFactory</span> <span class=operator>=</span> getTransactionFactoryFromEnvironment(environment);</span><br></pre></table></figure><p>获得到的TransactionFactory 就是 JdbcTransactionFactory ,而后<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br></pre><td class=code><pre><span class=line>tx = transactionFactory.newTransaction(environment.getDataSource(), level, autoCommit);</span><br><span class=line>```java</span><br><span class=line></span><br><span class=line>创建的transaction就是JdbcTransaction </span><br><span class=line>```java</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> Transaction <span class="title function_">newTransaction</span><span class=params>(DataSource ds, TransactionIsolationLevel level, <span class=type>boolean</span> autoCommit)</span> {</span><br><span class=line> <span class=keyword>return</span> <span class=keyword>new</span> <span class="title class_">JdbcTransaction</span>(ds, level, autoCommit, skipSetAutoCommitOnClose);</span><br><span class=line> }</span><br></pre></table></figure><p>然后我们再会上去看代码getConnection ,<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br></pre><td class=code><pre><span class=line><span class=keyword>protected</span> Connection <span class="title function_">getConnection</span><span class=params>(Log statementLog)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=comment>// -------> 这里的transaction就是JdbcTransaction</span></span><br><span class=line> <span class=type>Connection</span> <span class=variable>connection</span> <span class=operator>=</span> transaction.getConnection();</span><br><span class=line> <span class=keyword>if</span> (statementLog.isDebugEnabled()) {</span><br><span class=line> <span class=keyword>return</span> ConnectionLogger.newInstance(connection, statementLog, queryStack);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>return</span> connection;</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>即调用了<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br><span class=line>66</span><br><span class=line>67</span><br><span class=line>68</span><br><span class=line>69</span><br><span class=line>70</span><br><span class=line>71</span><br><span class=line>72</span><br><span class=line>73</span><br><span class=line>74</span><br><span class=line>75</span><br><span class=line>76</span><br><span class=line>77</span><br><span class=line>78</span><br><span class=line>79</span><br><span class=line>80</span><br><span class=line>81</span><br><span class=line>82</span><br><span class=line>83</span><br><span class=line>84</span><br><span class=line>85</span><br><span class=line>86</span><br><span class=line>87</span><br><span class=line>88</span><br><span class=line>89</span><br><span class=line>90</span><br><span class=line>91</span><br><span class=line>92</span><br><span class=line>93</span><br><span class=line>94</span><br><span class=line>95</span><br><span class=line>96</span><br><span class=line>97</span><br><span class=line>98</span><br><span class=line>99</span><br><span class=line>100</span><br><span class=line>101</span><br><span class=line>102</span><br><span class=line>103</span><br><span class=line>104</span><br><span class=line>105</span><br><span class=line>106</span><br><span class=line>107</span><br><span class=line>108</span><br><span class=line>109</span><br><span class=line>110</span><br><span class=line>111</span><br><span class=line>112</span><br><span class=line>113</span><br><span class=line>114</span><br><span class=line>115</span><br><span class=line>116</span><br><span class=line>117</span><br><span class=line>118</span><br><span class=line>119</span><br><span class=line>120</span><br><span class=line>121</span><br><span class=line>122</span><br><span class=line>123</span><br><span class=line>124</span><br><span class=line>125</span><br><span class=line>126</span><br><span class=line>127</span><br><span class=line>128</span><br><span class=line>129</span><br><span class=line>130</span><br><span class=line>131</span><br><span class=line>132</span><br><span class=line>133</span><br><span class=line>134</span><br><span class=line>135</span><br><span class=line>136</span><br><span class=line>137</span><br><span class=line>138</span><br><span class=line>139</span><br><span class=line>140</span><br><span class=line>141</span><br><span class=line>142</span><br></pre><td class=code><pre><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> Connection <span class="title function_">getConnection</span><span class=params>()</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=keyword>if</span> (connection == <span class=literal>null</span>) {</span><br><span class=line> openConnection();</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> connection;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>protected</span> <span class=keyword>void</span> <span class="title function_">openConnection</span><span class=params>()</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"Opening JDBC Connection"</span>);</span><br><span class=line> }</span><br><span class=line> connection = dataSource.getConnection();</span><br><span class=line> <span class=keyword>if</span> (level != <span class=literal>null</span>) {</span><br><span class=line> connection.setTransactionIsolation(level.getLevel());</span><br><span class=line> }</span><br><span class=line> setDesiredAutoCommit(autoCommit);</span><br><span class=line> }</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> Connection <span class="title function_">getConnection</span><span class=params>()</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=keyword>return</span> popConnection(dataSource.getUsername(), dataSource.getPassword()).getProxyConnection();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line><span class=keyword>private</span> PooledConnection <span class="title function_">popConnection</span><span class=params>(String username, String password)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>boolean</span> <span class=variable>countedWait</span> <span class=operator>=</span> <span class=literal>false</span>;</span><br><span class=line> <span class=type>PooledConnection</span> <span class=variable>conn</span> <span class=operator>=</span> <span class=literal>null</span>;</span><br><span class=line> <span class=type>long</span> <span class=variable>t</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line> <span class=type>int</span> <span class=variable>localBadConnectionCount</span> <span class=operator>=</span> <span class=number>0</span>;</span><br><span class=line></span><br><span class=line> <span class=keyword>while</span> (conn == <span class=literal>null</span>) {</span><br><span class=line> lock.lock();</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>if</span> (!state.idleConnections.isEmpty()) {</span><br><span class=line> <span class=comment>// Pool has available connection</span></span><br><span class=line> conn = state.idleConnections.remove(<span class=number>0</span>);</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"Checked out connection "</span> + conn.getRealHashCode() + <span class=string>" from pool."</span>);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=comment>// Pool does not have available connection</span></span><br><span class=line> <span class=keyword>if</span> (state.activeConnections.size() < poolMaximumActiveConnections) {</span><br><span class=line> <span class=comment>// Can create new connection</span></span><br><span class=line> <span class=comment>// ------------> 走到这里会创建PooledConnection,但是里面会先调用dataSource.getConnection()</span></span><br><span class=line> conn = <span class=keyword>new</span> <span class="title class_">PooledConnection</span>(dataSource.getConnection(), <span class=built_in>this</span>);</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"Created connection "</span> + conn.getRealHashCode() + <span class=string>"."</span>);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=comment>// Cannot create new connection</span></span><br><span class=line> <span class=type>PooledConnection</span> <span class=variable>oldestActiveConnection</span> <span class=operator>=</span> state.activeConnections.get(<span class=number>0</span>);</span><br><span class=line> <span class=type>long</span> <span class=variable>longestCheckoutTime</span> <span class=operator>=</span> oldestActiveConnection.getCheckoutTime();</span><br><span class=line> <span class=keyword>if</span> (longestCheckoutTime > poolMaximumCheckoutTime) {</span><br><span class=line> <span class=comment>// Can claim overdue connection</span></span><br><span class=line> state.claimedOverdueConnectionCount++;</span><br><span class=line> state.accumulatedCheckoutTimeOfOverdueConnections += longestCheckoutTime;</span><br><span class=line> state.accumulatedCheckoutTime += longestCheckoutTime;</span><br><span class=line> state.activeConnections.remove(oldestActiveConnection);</span><br><span class=line> <span class=keyword>if</span> (!oldestActiveConnection.getRealConnection().getAutoCommit()) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> oldestActiveConnection.getRealConnection().rollback();</span><br><span class=line> } <span class=keyword>catch</span> (SQLException e) {</span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> Just log a message for debug and continue to execute the following</span></span><br><span class=line><span class=comment> statement like nothing happened.</span></span><br><span class=line><span class=comment> Wrap the bad connection with a new PooledConnection, this will help</span></span><br><span class=line><span class=comment> to not interrupt current executing thread and give current thread a</span></span><br><span class=line><span class=comment> chance to join the next competition for another valid/good database</span></span><br><span class=line><span class=comment> connection. At the end of this loop, bad {@link @conn} will be set as null.</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> log.debug(<span class=string>"Bad connection. Could not roll back"</span>);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> conn = <span class=keyword>new</span> <span class="title class_">PooledConnection</span>(oldestActiveConnection.getRealConnection(), <span class=built_in>this</span>);</span><br><span class=line> conn.setCreatedTimestamp(oldestActiveConnection.getCreatedTimestamp());</span><br><span class=line> conn.setLastUsedTimestamp(oldestActiveConnection.getLastUsedTimestamp());</span><br><span class=line> oldestActiveConnection.invalidate();</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"Claimed overdue connection "</span> + conn.getRealHashCode() + <span class=string>"."</span>);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=comment>// Must wait</span></span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>if</span> (!countedWait) {</span><br><span class=line> state.hadToWaitCount++;</span><br><span class=line> countedWait = <span class=literal>true</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"Waiting as long as "</span> + poolTimeToWait + <span class=string>" milliseconds for connection."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=type>long</span> <span class=variable>wt</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line> condition.await(poolTimeToWait, TimeUnit.MILLISECONDS);</span><br><span class=line> state.accumulatedWaitTime += System.currentTimeMillis() - wt;</span><br><span class=line> } <span class=keyword>catch</span> (InterruptedException e) {</span><br><span class=line> <span class=comment>// set interrupt flag</span></span><br><span class=line> Thread.currentThread().interrupt();</span><br><span class=line> <span class=keyword>break</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (conn != <span class=literal>null</span>) {</span><br><span class=line> <span class=comment>// ping to server and check the connection is valid or not</span></span><br><span class=line> <span class=keyword>if</span> (conn.isValid()) {</span><br><span class=line> <span class=keyword>if</span> (!conn.getRealConnection().getAutoCommit()) {</span><br><span class=line> conn.getRealConnection().rollback();</span><br><span class=line> }</span><br><span class=line> conn.setConnectionTypeCode(assembleConnectionTypeCode(dataSource.getUrl(), username, password));</span><br><span class=line> conn.setCheckoutTimestamp(System.currentTimeMillis());</span><br><span class=line> conn.setLastUsedTimestamp(System.currentTimeMillis());</span><br><span class=line> state.activeConnections.add(conn);</span><br><span class=line> state.requestCount++;</span><br><span class=line> state.accumulatedRequestTime += System.currentTimeMillis() - t;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"A bad connection ("</span> + conn.getRealHashCode() + <span class=string>") was returned from the pool, getting another connection."</span>);</span><br><span class=line> }</span><br><span class=line> state.badConnectionCount++;</span><br><span class=line> localBadConnectionCount++;</span><br><span class=line> conn = <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>if</span> (localBadConnectionCount > (poolMaximumIdleConnections + poolMaximumLocalBadConnectionTolerance)) {</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"PooledDataSource: Could not get a good connection to the database."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">SQLException</span>(<span class=string>"PooledDataSource: Could not get a good connection to the database."</span>);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>finally</span> {</span><br><span class=line> lock.unlock();</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (conn == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>if</span> (log.isDebugEnabled()) {</span><br><span class=line> log.debug(<span class=string>"PooledDataSource: Unknown severe error condition. The connection pool returned a null connection."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">SQLException</span>(<span class=string>"PooledDataSource: Unknown severe error condition. The connection pool returned a null connection."</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> conn;</span><br><span class=line> }</span><br></pre></table></figure><p>其实就是调用的<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br></pre><td class=code><pre><span class=line><span class=comment>// org.apache.ibatis.datasource.unpooled.UnpooledDataSource#getConnection()</span></span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> Connection <span class="title function_">getConnection</span><span class=params>()</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=keyword>return</span> doGetConnection(username, password);</span><br><span class=line> }</span><br><span class=line>```java</span><br><span class=line></span><br><span class=line>然后就是</span><br><span class=line>```java</span><br><span class=line><span class=keyword>private</span> Connection <span class="title function_">doGetConnection</span><span class=params>(String username, String password)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=type>Properties</span> <span class=variable>props</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">Properties</span>();</span><br><span class=line> <span class=keyword>if</span> (driverProperties != <span class=literal>null</span>) {</span><br><span class=line> props.putAll(driverProperties);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (username != <span class=literal>null</span>) {</span><br><span class=line> props.setProperty(<span class=string>"user"</span>, username);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (password != <span class=literal>null</span>) {</span><br><span class=line> props.setProperty(<span class=string>"password"</span>, password);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> doGetConnection(props);</span><br><span class=line> }</span><br></pre></table></figure><p>继续这个逻辑<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br><span class=line>34</span><br><span class=line>35</span><br><span class=line>36</span><br><span class=line>37</span><br><span class=line>38</span><br><span class=line>39</span><br><span class=line>40</span><br><span class=line>41</span><br><span class=line>42</span><br><span class=line>43</span><br><span class=line>44</span><br><span class=line>45</span><br><span class=line>46</span><br><span class=line>47</span><br><span class=line>48</span><br><span class=line>49</span><br><span class=line>50</span><br><span class=line>51</span><br><span class=line>52</span><br><span class=line>53</span><br><span class=line>54</span><br><span class=line>55</span><br><span class=line>56</span><br><span class=line>57</span><br><span class=line>58</span><br><span class=line>59</span><br><span class=line>60</span><br><span class=line>61</span><br><span class=line>62</span><br><span class=line>63</span><br><span class=line>64</span><br><span class=line>65</span><br><span class=line>66</span><br><span class=line>67</span><br><span class=line>68</span><br><span class=line>69</span><br><span class=line>70</span><br><span class=line>71</span><br><span class=line>72</span><br></pre><td class=code><pre><span class=line> <span class=keyword>private</span> Connection <span class="title function_">doGetConnection</span><span class=params>(Properties properties)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> initializeDriver();</span><br><span class=line> <span class=type>Connection</span> <span class=variable>connection</span> <span class=operator>=</span> DriverManager.getConnection(url, properties);</span><br><span class=line> configureConnection(connection);</span><br><span class=line> <span class=keyword>return</span> connection;</span><br><span class=line> }</span><br><span class=line> <span class=meta>@CallerSensitive</span></span><br><span class=line> <span class=keyword>public</span> <span class=keyword>static</span> Connection <span class="title function_">getConnection</span><span class=params>(String url,</span></span><br><span class=line><span class=params> java.util.Properties info)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> (getConnection(url, info, Reflection.getCallerClass()));</span><br><span class=line> }</span><br><span class=line><span class=keyword>private</span> <span class=keyword>static</span> Connection <span class="title function_">getConnection</span><span class=params>(</span></span><br><span class=line><span class=params> String url, java.util.Properties info, Class<?> caller)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=comment>/*</span></span><br><span class=line><span class=comment> * When callerCl is null, we should check the application's</span></span><br><span class=line><span class=comment> * (which is invoking this class indirectly)</span></span><br><span class=line><span class=comment> * classloader, so that the JDBC driver class outside rt.jar</span></span><br><span class=line><span class=comment> * can be loaded from here.</span></span><br><span class=line><span class=comment> */</span></span><br><span class=line> <span class=type>ClassLoader</span> <span class=variable>callerCL</span> <span class=operator>=</span> caller != <span class=literal>null</span> ? caller.getClassLoader() : <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>synchronized</span>(DriverManager.class) {</span><br><span class=line> <span class=comment>// synchronize loading of the correct classloader.</span></span><br><span class=line> <span class=keyword>if</span> (callerCL == <span class=literal>null</span>) {</span><br><span class=line> callerCL = Thread.currentThread().getContextClassLoader();</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span>(url == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">SQLException</span>(<span class=string>"The url cannot be null"</span>, <span class=string>"08001"</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> println(<span class=string>"DriverManager.getConnection(\""</span> + url + <span class=string>"\")"</span>);</span><br><span class=line></span><br><span class=line> <span class=comment>// Walk through the loaded registeredDrivers attempting to make a connection.</span></span><br><span class=line> <span class=comment>// Remember the first exception that gets raised so we can reraise it.</span></span><br><span class=line> <span class=type>SQLException</span> <span class=variable>reason</span> <span class=operator>=</span> <span class=literal>null</span>;</span><br><span class=line></span><br><span class=line> <span class=keyword>for</span>(DriverInfo aDriver : registeredDrivers) {</span><br><span class=line> <span class=comment>// If the caller does not have permission to load the driver then</span></span><br><span class=line> <span class=comment>// skip it.</span></span><br><span class=line> <span class=keyword>if</span>(isDriverAllowed(aDriver.driver, callerCL)) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=comment>// ----------> driver[className=com.mysql.cj.jdbc.Driver@64030b91]</span></span><br><span class=line> println(<span class=string>" trying "</span> + aDriver.driver.getClass().getName());</span><br><span class=line> <span class=type>Connection</span> <span class=variable>con</span> <span class=operator>=</span> aDriver.driver.connect(url, info);</span><br><span class=line> <span class=keyword>if</span> (con != <span class=literal>null</span>) {</span><br><span class=line> <span class=comment>// Success!</span></span><br><span class=line> println(<span class=string>"getConnection returning "</span> + aDriver.driver.getClass().getName());</span><br><span class=line> <span class=keyword>return</span> (con);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>catch</span> (SQLException ex) {</span><br><span class=line> <span class=keyword>if</span> (reason == <span class=literal>null</span>) {</span><br><span class=line> reason = ex;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> println(<span class=string>" skipping: "</span> + aDriver.getClass().getName());</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// if we got here nobody could connect.</span></span><br><span class=line> <span class=keyword>if</span> (reason != <span class=literal>null</span>) {</span><br><span class=line> println(<span class=string>"getConnection failed: "</span> + reason);</span><br><span class=line> <span class=keyword>throw</span> reason;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> println(<span class=string>"getConnection: no suitable driver found for "</span>+ url);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">SQLException</span>(<span class=string>"No suitable driver found for "</span>+ url, <span class=string>"08001"</span>);</span><br><span class=line> }</span><br></pre></table></figure><p>上面的driver就是driver[className=com.mysql.cj.jdbc.Driver@64030b91]<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br><span class=line>10</span><br><span class=line>11</span><br><span class=line>12</span><br><span class=line>13</span><br><span class=line>14</span><br><span class=line>15</span><br><span class=line>16</span><br><span class=line>17</span><br><span class=line>18</span><br><span class=line>19</span><br><span class=line>20</span><br><span class=line>21</span><br><span class=line>22</span><br><span class=line>23</span><br><span class=line>24</span><br><span class=line>25</span><br><span class=line>26</span><br><span class=line>27</span><br><span class=line>28</span><br><span class=line>29</span><br><span class=line>30</span><br><span class=line>31</span><br><span class=line>32</span><br><span class=line>33</span><br></pre><td class=code><pre><span class=line><span class=comment>// com.mysql.cj.jdbc.NonRegisteringDriver#connect</span></span><br><span class=line><span class=keyword>public</span> Connection <span class="title function_">connect</span><span class=params>(String url, Properties info)</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>if</span> (!ConnectionUrl.acceptsUrl(url)) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>ConnectionUrl</span> <span class=variable>conStr</span> <span class=operator>=</span> ConnectionUrl.getConnectionUrlInstance(url, info);</span><br><span class=line> <span class=keyword>switch</span> (conStr.getType()) {</span><br><span class=line> <span class=keyword>case</span> SINGLE_CONNECTION:</span><br><span class=line> <span class=keyword>return</span> ConnectionImpl.getInstance(conStr.getMainHost());</span><br><span class=line> <span class=keyword>case</span> FAILOVER_CONNECTION:</span><br><span class=line> <span class=keyword>case</span> FAILOVER_DNS_SRV_CONNECTION:</span><br><span class=line> <span class=keyword>return</span> FailoverConnectionProxy.createProxyInstance(conStr);</span><br><span class=line> <span class=keyword>case</span> LOADBALANCE_CONNECTION:</span><br><span class=line> <span class=keyword>case</span> LOADBALANCE_DNS_SRV_CONNECTION:</span><br><span class=line> <span class=keyword>return</span> LoadBalancedConnectionProxy.createProxyInstance(conStr);</span><br><span class=line> <span class=keyword>case</span> REPLICATION_CONNECTION:</span><br><span class=line> <span class=keyword>case</span> REPLICATION_DNS_SRV_CONNECTION:</span><br><span class=line> <span class=keyword>return</span> ReplicationConnectionProxy.createProxyInstance(conStr);</span><br><span class=line> <span class=keyword>default</span>:</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>catch</span> (UnsupportedConnectionStringException var5) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>null</span>;</span><br><span class=line> } <span class=keyword>catch</span> (CJException var6) {</span><br><span class=line> <span class=keyword>throw</span> (UnableToConnectException)ExceptionFactory.createException(UnableToConnectException.class, Messages.getString(<span class=string>"NonRegisteringDriver.17"</span>, <span class=keyword>new</span> <span class="title class_">Object</span>[]{var6.toString()}), var6);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>catch</span> (CJException var7) {</span><br><span class=line> <span class=keyword>throw</span> SQLExceptionsMapping.translateException(var7);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>这是个 SINGLE_CONNECTION ,所以调用的就是 return ConnectionImpl.getInstance(conStr.getMainHost());<br>然后在这里设置了代理类<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br><span class=line>5</span><br><span class=line>6</span><br><span class=line>7</span><br><span class=line>8</span><br><span class=line>9</span><br></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class="title function_">PooledConnection</span><span class=params>(Connection connection, PooledDataSource dataSource)</span> {</span><br><span class=line> <span class=built_in>this</span>.hashCode = connection.hashCode();</span><br><span class=line> <span class=built_in>this</span>.realConnection = connection;</span><br><span class=line> <span class=built_in>this</span>.dataSource = dataSource;</span><br><span class=line> <span class=built_in>this</span>.createdTimestamp = System.currentTimeMillis();</span><br><span class=line> <span class=built_in>this</span>.lastUsedTimestamp = System.currentTimeMillis();</span><br><span class=line> <span class=built_in>this</span>.valid = <span class=literal>true</span>;</span><br><span class=line> <span class=built_in>this</span>.proxyConnection = (Connection) Proxy.newProxyInstance(Connection.class.getClassLoader(), IFACES, <span class=built_in>this</span>);</span><br><span class=line> }</span><br></pre></table></figure><p>结合这个<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br><span class=line>2</span><br><span class=line>3</span><br><span class=line>4</span><br></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line><span class=keyword>public</span> Connection <span class="title function_">getConnection</span><span class=params>()</span> <span class=keyword>throws</span> SQLException {</span><br><span class=line> <span class=keyword>return</span> popConnection(dataSource.getUsername(), dataSource.getPassword()).getProxyConnection();</span><br><span class=line>}</span><br></pre></table></figure><p>所以最终的connection就是com.mysql.cj.jdbc.ConnectionImpl@358ab600</div><footer class=post-footer><div class="affiliate-creative affiliate-creative--post-end" data-affiliate-id=tencent-cloud-general><a rel="sponsored noopener" aria-label=腾讯云产品优惠 href=https://cloud.tencent.com/act/cps/redirect?redirect=2446&cps_key=2e33a1eedb380997d03618b4a5ba6ca7&from=console target=_blank><img alt=腾讯云服务器、数据库和云产品优惠 decoding=async height=419 loading=lazy src=/uploads/affiliate/tencent-cloud-general.webp width=690> </a><span class=affiliate-disclosure>推广</span></div><div class=reward-container><div>请我一杯咖啡吧!</div><button>赞赏</button><div class=post-reward><div><img alt="Nicksxs 微信" 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