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content="log 初始化过程,首先是在启动类里会获取 logger。继续下去是 org.apache.commons.logging.impl.SLF4JLogFactory#getInstance(java.lang.Class)" itemprop=description></span><header class=post-header><h1 itemprop="name headline" class=post-title>聊一下 Java 的日志系列二</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:2024-01-14 21:26:53" datetime=2024-01-14T21:26:53+08:00>2024-01-14</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><span class="post-meta-item cloudflare-page-counter" data-title="聊一下 Java 的日志系列二" data-increment=true data-path=/2024/01/14/%E8%81%8A%E4%B8%80%E4%B8%8B-Java-%E7%9A%84%E6%97%A5%E5%BF%97%E7%B3%BB%E5%88%97%E4%BA%8C/ 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>log 初始化过程,首先是在启动类里会获取 logger。继续下去是 org.apache.commons.logging.impl.SLF4JLogFactory#getInstance(java.lang.Class)</div></div></header><div class=post-body itemprop=articleBody><p>log 初始化过程,首先是在启动类里会获取 logger<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=keyword>private</span> <span class=keyword>static</span> <span class=keyword>final</span> <span class=type>Log</span> <span class=variable>logger</span> <span class=operator>=</span> LogFactory.getLog(SpringApplication.class);</span><br></pre></table></figure><p>然后是<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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>static</span> Log <span class="title function_">getLog</span><span class=params>(Class clazz)</span> <span class=keyword>throws</span> LogConfigurationException {</span><br><span class=line> <span class=keyword>return</span> getFactory().getInstance(clazz);</span><br><span class=line> }</span><br></pre></table></figure><p>继续下去是<br><code>org.apache.commons.logging.impl.SLF4JLogFactory#getInstance(java.lang.Class)</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> Log <span class="title function_">getInstance</span><span class=params>(Class clazz)</span> <span class=keyword>throws</span> LogConfigurationException {</span><br><span class=line> <span class=keyword>return</span> <span class=built_in>this</span>.getInstance(clazz.getName());</span><br><span class=line>}</span><br><span class=line><span class=keyword>public</span> Log <span class="title function_">getInstance</span><span class=params>(String name)</span> <span class=keyword>throws</span> LogConfigurationException {</span><br><span class=line> <span class=type>Log</span> <span class=variable>instance</span> <span class=operator>=</span> (Log)<span class=built_in>this</span>.loggerMap.get(name);</span><br><span class=line> <span class=keyword>if</span> (instance != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> instance;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>Logger</span> <span class=variable>slf4jLogger</span> <span class=operator>=</span> LoggerFactory.getLogger(name);</span><br><span class=line> Object newInstance;</span><br><span class=line> <span class=keyword>if</span> (slf4jLogger <span class=keyword>instanceof</span> LocationAwareLogger) {</span><br><span class=line> newInstance = <span class=keyword>new</span> <span class="title class_">SLF4JLocationAwareLog</span>((LocationAwareLogger)slf4jLogger);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> newInstance = <span class=keyword>new</span> <span class="title class_">SLF4JLog</span>(slf4jLogger);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=type>Log</span> <span class=variable>oldInstance</span> <span class=operator>=</span> (Log)<span class=built_in>this</span>.loggerMap.putIfAbsent(name, newInstance);</span><br><span class=line> <span class=keyword>return</span> (Log)(oldInstance == <span class=literal>null</span> ? newInstance : oldInstance);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>然后再往下处理就是 <code>LoggerFactory.getLogger(name);</code> 了,跟普通的获取 logger 一样<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=keyword>public</span> <span class=keyword>static</span> Logger <span class="title function_">getLogger</span><span class=params>(String name)</span> {</span><br><span class=line> <span class=type>ILoggerFactory</span> <span class=variable>iLoggerFactory</span> <span class=operator>=</span> getILoggerFactory();</span><br><span class=line> <span class=keyword>return</span> iLoggerFactory.getLogger(name);</span><br><span class=line>}</span><br></pre></table></figure><p>继续下去会先判断是否已初始化<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>public</span> <span class=keyword>static</span> ILoggerFactory <span class="title function_">getILoggerFactory</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>if</span> (INITIALIZATION_STATE == UNINITIALIZED) {</span><br><span class=line> <span class=keyword>synchronized</span> (LoggerFactory.class) {</span><br><span class=line> <span class=keyword>if</span> (INITIALIZATION_STATE == UNINITIALIZED) {</span><br><span class=line> INITIALIZATION_STATE = ONGOING_INITIALIZATION;</span><br><span class=line> performInitialization();</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> <span class=keyword>switch</span> (INITIALIZATION_STATE) {</span><br><span class=line> <span class=keyword>case</span> SUCCESSFUL_INITIALIZATION:</span><br><span class=line> <span class=keyword>return</span> StaticLoggerBinder.getSingleton().getLoggerFactory();</span><br><span class=line> <span class=keyword>case</span> NOP_FALLBACK_INITIALIZATION:</span><br><span class=line> <span class=keyword>return</span> NOP_FALLBACK_FACTORY;</span><br><span class=line> <span class=keyword>case</span> FAILED_INITIALIZATION:</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">IllegalStateException</span>(UNSUCCESSFUL_INIT_MSG);</span><br><span class=line> <span class=keyword>case</span> ONGOING_INITIALIZATION:</span><br><span class=line> <span class=comment>// support re-entrant behavior.</span></span><br><span class=line> <span class=comment>// See also http://jira.qos.ch/browse/SLF4J-97</span></span><br><span class=line> <span class=keyword>return</span> SUBST_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_">IllegalStateException</span>(<span class=string>"Unreachable code"</span>);</span><br><span class=line> }</span><br></pre></table></figure><p>第一次调用的话就会走到 <code>org.slf4j.LoggerFactory#performInitialization</code> 里面是先调用绑定,这也是 slf4j 门面模式的特点<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=keyword>private</span> <span class=keyword>final</span> <span class=keyword>static</span> <span class=keyword>void</span> <span class="title function_">performInitialization</span><span class=params>()</span> {</span><br><span class=line> bind();</span><br><span class=line> <span class=keyword>if</span> (INITIALIZATION_STATE == SUCCESSFUL_INITIALIZATION) {</span><br><span class=line> versionSanityCheck();</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><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></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=keyword>final</span> <span class=keyword>static</span> <span class=keyword>void</span> <span class="title function_">bind</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> Set&LTURL> staticLoggerBinderPathSet = <span class=literal>null</span>;</span><br><span class=line> <span class=comment>// skip check under android, see also</span></span><br><span class=line> <span class=comment>// http://jira.qos.ch/browse/SLF4J-328</span></span><br><span class=line> <span class=keyword>if</span> (!isAndroid()) {</span><br><span class=line> staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet();</span><br><span class=line> reportMultipleBindingAmbiguity(staticLoggerBinderPathSet);</span><br><span class=line> }</span><br><span class=line> <span class=comment>// the next line does the binding</span></span><br><span class=line> StaticLoggerBinder.getSingleton();</span><br><span class=line> INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION;</span><br><span class=line> reportActualBinding(staticLoggerBinderPathSet);</span><br><span class=line> fixSubstituteLoggers();</span><br><span class=line> replayEvents();</span><br><span class=line> <span class=comment>// release all resources in SUBST_FACTORY</span></span><br><span class=line> SUBST_FACTORY.clear();</span><br><span class=line> } <span class=keyword>catch</span> (NoClassDefFoundError ncde) {</span><br><span class=line> <span class=type>String</span> <span class=variable>msg</span> <span class=operator>=</span> ncde.getMessage();</span><br><span class=line> <span class=keyword>if</span> (messageContainsOrgSlf4jImplStaticLoggerBinder(msg)) {</span><br><span class=line> INITIALIZATION_STATE = NOP_FALLBACK_INITIALIZATION;</span><br><span class=line> Util.report(<span class=string>"Failed to load class \"org.slf4j.impl.StaticLoggerBinder\"."</span>);</span><br><span class=line> Util.report(<span class=string>"Defaulting to no-operation (NOP) logger implementation"</span>);</span><br><span class=line> Util.report(<span class=string>"See "</span> + NO_STATICLOGGERBINDER_URL + <span class=string>" for further details."</span>);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> failedBinding(ncde);</span><br><span class=line> <span class=keyword>throw</span> ncde;</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>catch</span> (java.lang.NoSuchMethodError nsme) {</span><br><span class=line> <span class=type>String</span> <span class=variable>msg</span> <span class=operator>=</span> nsme.getMessage();</span><br><span class=line> <span class=keyword>if</span> (msg != <span class=literal>null</span> && msg.contains(<span class=string>"org.slf4j.impl.StaticLoggerBinder.getSingleton()"</span>)) {</span><br><span class=line> INITIALIZATION_STATE = FAILED_INITIALIZATION;</span><br><span class=line> Util.report(<span class=string>"slf4j-api 1.6.x (or later) is incompatible with this binding."</span>);</span><br><span class=line> Util.report(<span class=string>"Your binding is version 1.5.5 or earlier."</span>);</span><br><span class=line> Util.report(<span class=string>"Upgrade your binding to version 1.6.x."</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>throw</span> nsme;</span><br><span class=line> } <span class=keyword>catch</span> (Exception e) {</span><br><span class=line> failedBinding(e);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">IllegalStateException</span>(<span class=string>"Unexpected initialization failure"</span>, e);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>非安卓环境会进入第一个 if 逻辑,先要去找static_logger_binder<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=keyword>static</span> Set&LTURL> <span class="title function_">findPossibleStaticLoggerBinderPathSet</span><span class=params>()</span> {</span><br><span class=line> <span class=comment>// use Set instead of list in order to deal with bug #138</span></span><br><span class=line> <span class=comment>// LinkedHashSet appropriate here because it preserves insertion order</span></span><br><span class=line> <span class=comment>// during iteration</span></span><br><span class=line> Set&LTURL> staticLoggerBinderPathSet = <span class=keyword>new</span> <span class="title class_">LinkedHashSet</span>&LTURL>();</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=type>ClassLoader</span> <span class=variable>loggerFactoryClassLoader</span> <span class=operator>=</span> LoggerFactory.class.getClassLoader();</span><br><span class=line> Enumeration&LTURL> paths;</span><br><span class=line> <span class=keyword>if</span> (loggerFactoryClassLoader == <span class=literal>null</span>) {</span><br><span class=line> paths = ClassLoader.getSystemResources(STATIC_LOGGER_BINDER_PATH);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> paths = loggerFactoryClassLoader.getResources(STATIC_LOGGER_BINDER_PATH);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>while</span> (paths.hasMoreElements()) {</span><br><span class=line> <span class=type>URL</span> <span class=variable>path</span> <span class=operator>=</span> paths.nextElement();</span><br><span class=line> staticLoggerBinderPathSet.add(path);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>catch</span> (IOException ioe) {</span><br><span class=line> Util.report(<span class=string>"Error getting resources from path"</span>, ioe);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> staticLoggerBinderPathSet;</span><br><span class=line> }</span><br></pre></table></figure><p>上面的 <code>STATIC_LOGGER_BINDER_PATH</code><br>就是 <code>org/slf4j/impl/StaticLoggerBinder.class</code> 如果找不到在外层方法就会抛出 <code>NoSuchMethodError</code> 错误,然后就是通过 <code>StaticLoggerBinder.getSingleton();</code> 获取 <code>StaticLoggerBinder</code> 实例了<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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>static</span> StaticLoggerBinder <span class="title function_">getSingleton</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>return</span> SINGLETON;</span><br><span class=line>}</span><br><span class=line><span class=keyword>private</span> <span class=keyword>static</span> <span class=type>StaticLoggerBinder</span> <span class=variable>SINGLETON</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">StaticLoggerBinder</span>();</span><br></pre></table></figure><p>比较重要的是这里的 static 代码块还有一个逻辑,就是下面这个初始化逻辑<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></pre><td class=code><pre><span class=line><span class=keyword>static</span> {</span><br><span class=line> SINGLETON.init();</span><br><span class=line>}</span><br><span class=line><span class=keyword>void</span> <span class="title function_">init</span><span class=params>()</span> {</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>new</span> <span class="title class_">ContextInitializer</span>(defaultLoggerContext).autoConfig();</span><br><span class=line> } <span class=keyword>catch</span> (JoranException je) {</span><br><span class=line> Util.report(<span class=string>"Failed to auto configure default logger context"</span>, je);</span><br><span class=line> }</span><br><span class=line> <span class=comment>// logback-292</span></span><br><span class=line> <span class=keyword>if</span> (!StatusUtil.contextHasStatusListener(defaultLoggerContext)) {</span><br><span class=line> StatusPrinter.printInCaseOfErrorsOrWarnings(defaultLoggerContext);</span><br><span class=line> }</span><br><span class=line> contextSelectorBinder.init(defaultLoggerContext, KEY);</span><br><span class=line> initialized = <span class=literal>true</span>;</span><br><span class=line> } <span class=keyword>catch</span> (Exception t) { <span class=comment>// see LOGBACK-1159</span></span><br><span class=line> Util.report(<span class=string>"Failed to instantiate ["</span> + LoggerContext.class.getName() + <span class=string>"]"</span>, t);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>上面的 defaultLoggerContext 也是通过静态代码块处理的<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=keyword>private</span> <span class=type>LoggerContext</span> <span class=variable>defaultLoggerContext</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">LoggerContext</span>();</span><br></pre></table></figure><p>然后是调用 <code>ch.qos.logback.classic.util.ContextInitializer#autoConfig</code> 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><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=keyword>public</span> <span class=keyword>void</span> <span class="title function_">autoConfig</span><span class=params>()</span> <span class=keyword>throws</span> JoranException {</span><br><span class=line> StatusListenerConfigHelper.installIfAsked(loggerContext);</span><br><span class=line> <span class=type>URL</span> <span class=variable>url</span> <span class=operator>=</span> findURLOfDefaultConfigurationFile(<span class=literal>true</span>);</span><br><span class=line> <span class=keyword>if</span> (url != <span class=literal>null</span>) {</span><br><span class=line> configureByResource(url);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>Configurator</span> <span class=variable>c</span> <span class=operator>=</span> EnvUtil.loadFromServiceLoader(Configurator.class);</span><br><span class=line> <span class=keyword>if</span> (c != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> c.setContext(loggerContext);</span><br><span class=line> c.configure(loggerContext);</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_">LogbackException</span>(String.format(<span class=string>"Failed to initialize Configurator: %s using ServiceLoader"</span>, c != <span class=literal>null</span> ? c.getClass()</span><br><span class=line> .getCanonicalName() : <span class=string>"null"</span>), e);</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>BasicConfigurator</span> <span class=variable>basicConfigurator</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">BasicConfigurator</span>();</span><br><span class=line> basicConfigurator.setContext(loggerContext);</span><br><span class=line> basicConfigurator.configure(loggerContext);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>前面会先查找配置文件路径<br><code>URL url = findURLOfDefaultConfigurationFile(true);</code> 还是调用这个类内的 <code>ch.qos.logback.classic.util.ContextInitializer#findURLOfDefaultConfigurationFile</code> 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><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></pre><td class=code><pre><span class=line><span class=keyword>public</span> URL <span class="title function_">findURLOfDefaultConfigurationFile</span><span class=params>(<span class=type>boolean</span> updateStatus)</span> {</span><br><span class=line> <span class=type>ClassLoader</span> <span class=variable>myClassLoader</span> <span class=operator>=</span> Loader.getClassLoaderOfObject(<span class=built_in>this</span>);</span><br><span class=line> <span class=type>URL</span> <span class=variable>url</span> <span class=operator>=</span> findConfigFileURLFromSystemProperties(myClassLoader, updateStatus);</span><br><span class=line> <span class=keyword>if</span> (url != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> url;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> url = getResource(TEST_AUTOCONFIG_FILE, myClassLoader, updateStatus);</span><br><span class=line> <span class=keyword>if</span> (url != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> url;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> url = getResource(GROOVY_AUTOCONFIG_FILE, myClassLoader, updateStatus);</span><br><span class=line> <span class=keyword>if</span> (url != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> url;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> getResource(AUTOCONFIG_FILE, myClassLoader, updateStatus);</span><br><span class=line>}</span><br></pre></table></figure><p>才发现原来这里也是硬编码了文件名<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=keyword>class</span> <span class="title class_">ContextInitializer</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>final</span> <span class=keyword>public</span> <span class=keyword>static</span> <span class=type>String</span> <span class=variable>GROOVY_AUTOCONFIG_FILE</span> <span class=operator>=</span> <span class=string>"logback.groovy"</span>;</span><br><span class=line> <span class=keyword>final</span> <span class=keyword>public</span> <span class=keyword>static</span> <span class=type>String</span> <span class=variable>AUTOCONFIG_FILE</span> <span class=operator>=</span> <span class=string>"logback.xml"</span>;</span><br><span class=line> <span class=keyword>final</span> <span class=keyword>public</span> <span class=keyword>static</span> <span class=type>String</span> <span class=variable>TEST_AUTOCONFIG_FILE</span> <span class=operator>=</span> <span class=string>"logback-test.xml"</span>;</span><br><span class=line> <span class=keyword>final</span> <span class=keyword>public</span> <span class=keyword>static</span> <span class=type>String</span> <span class=variable>CONFIG_FILE_PROPERTY</span> <span class=operator>=</span> <span class=string>"logback.configurationFile"</span>;</span><br><span class=line></span><br></pre></table></figure><p>如果不为空就调用了<br><code>ch.qos.logback.classic.util.ContextInitializer#configureByResource</code> 这边是根据后缀判断处理方法<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><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=keyword>public</span> <span class=keyword>void</span> <span class="title function_">configureByResource</span><span class=params>(URL url)</span> <span class=keyword>throws</span> JoranException {</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_">IllegalArgumentException</span>(<span class=string>"URL argument cannot be null"</span>);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>final</span> <span class=type>String</span> <span class=variable>urlString</span> <span class=operator>=</span> url.toString();</span><br><span class=line> <span class=keyword>if</span> (urlString.endsWith(<span class=string>"groovy"</span>)) {</span><br><span class=line> <span class=keyword>if</span> (EnvUtil.isGroovyAvailable()) {</span><br><span class=line> <span class=comment>// avoid directly referring to GafferConfigurator so as to avoid</span></span><br><span class=line> <span class=comment>// loading groovy.lang.GroovyObject . See also http://jira.qos.ch/browse/LBCLASSIC-214</span></span><br><span class=line> GafferUtil.runGafferConfiguratorOn(loggerContext, <span class=built_in>this</span>, url);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>StatusManager</span> <span class=variable>sm</span> <span class=operator>=</span> loggerContext.getStatusManager();</span><br><span class=line> sm.add(<span class=keyword>new</span> <span class="title class_">ErrorStatus</span>(<span class=string>"Groovy classes are not available on the class path. ABORTING INITIALIZATION."</span>, loggerContext));</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> <span class=keyword>if</span> (urlString.endsWith(<span class=string>"xml"</span>)) {</span><br><span class=line> <span class=type>JoranConfigurator</span> <span class=variable>configurator</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">JoranConfigurator</span>();</span><br><span class=line> configurator.setContext(loggerContext);</span><br><span class=line> configurator.doConfigure(url);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">LogbackException</span>(<span class=string>"Unexpected filename extension of file ["</span> + url.toString() + <span class=string>"]. Should be either .groovy or .xml"</span>);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>因为我们找到的是 logback.xml,所以走的是<br><code>ch.qos.logback.classic.joran.JoranConfigurator</code> ,<br>然后调用了<br><code>ch.qos.logback.core.joran.GenericConfigurator#doConfigure(java.net.URL)</code><br>这个 <code>GenericConfigurator</code> 是 <code>JoranConfigurator</code> 的父类<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><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>public</span> <span class=keyword>final</span> <span class=keyword>void</span> <span class="title function_">doConfigure</span><span class=params>(URL url)</span> <span class=keyword>throws</span> JoranException {</span><br><span class=line> <span class=type>InputStream</span> <span class=variable>in</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> informContextOfURLUsedForConfiguration(getContext(), url);</span><br><span class=line> <span class=type>URLConnection</span> <span class=variable>urlConnection</span> <span class=operator>=</span> url.openConnection();</span><br><span class=line> <span class=comment>// per http://jira.qos.ch/browse/LBCORE-105</span></span><br><span class=line> <span class=comment>// per http://jira.qos.ch/browse/LBCORE-127</span></span><br><span class=line> urlConnection.setUseCaches(<span class=literal>false</span>);</span><br><span class=line></span><br><span class=line> in = urlConnection.getInputStream();</span><br><span class=line> doConfigure(in, url.toExternalForm());</span><br><span class=line> } <span class=keyword>catch</span> (IOException ioe) {</span><br><span class=line> <span class=type>String</span> <span class=variable>errMsg</span> <span class=operator>=</span> <span class=string>"Could not open URL ["</span> + url + <span class=string>"]."</span>;</span><br><span class=line> addError(errMsg, ioe);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">JoranException</span>(errMsg, ioe);</span><br><span class=line> } <span class=keyword>finally</span> {</span><br><span class=line> <span class=keyword>if</span> (in != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> in.close();</span><br><span class=line> } <span class=keyword>catch</span> (IOException ioe) {</span><br><span class=line> <span class=type>String</span> <span class=variable>errMsg</span> <span class=operator>=</span> <span class=string>"Could not close input stream"</span>;</span><br><span class=line> addError(errMsg, ioe);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">JoranException</span>(errMsg, ioe);</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>然后继续调用<br><code>ch.qos.logback.core.joran.GenericConfigurator#doConfigure(java.io.InputStream, java.lang.String)</code> 处理具体的内容,前面处理了内容获取,因为如果是走的 url 文件就需要从网络获取文件流,<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=keyword>final</span> <span class=keyword>void</span> <span class="title function_">doConfigure</span><span class=params>(InputStream inputStream, String systemId)</span> <span class=keyword>throws</span> JoranException {</span><br><span class=line> <span class=type>InputSource</span> <span class=variable>inputSource</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">InputSource</span>(inputStream);</span><br><span class=line> inputSource.setSystemId(systemId);</span><br><span class=line> doConfigure(inputSource);</span><br><span class=line>}</span><br></pre></table></figure><p>而实际的处理 xml 内容则是在<br><code>ch.qos.logback.core.joran.GenericConfigurator#doConfigure(org.xml.sax.InputSource)</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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>final</span> <span class=keyword>void</span> <span class="title function_">doConfigure</span><span class=params>(<span class=keyword>final</span> InputSource inputSource)</span> <span class=keyword>throws</span> JoranException {</span><br><span class=line></span><br><span class=line> <span class=type>long</span> <span class=variable>threshold</span> <span class=operator>=</span> System.currentTimeMillis();</span><br><span class=line> <span class=comment>// if (!ConfigurationWatchListUtil.wasConfigurationWatchListReset(context)) {</span></span><br><span class=line> <span class=comment>// informContextOfURLUsedForConfiguration(getContext(), null);</span></span><br><span class=line> <span class=comment>// }</span></span><br><span class=line> <span class=type>SaxEventRecorder</span> <span class=variable>recorder</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">SaxEventRecorder</span>(context);</span><br><span class=line> recorder.recordEvents(inputSource);</span><br><span class=line> doConfigure(recorder.saxEventList);</span><br><span class=line> <span class=comment>// no exceptions a this level</span></span><br><span class=line> <span class=type>StatusUtil</span> <span class=variable>statusUtil</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">StatusUtil</span>(context);</span><br><span class=line> <span class=keyword>if</span> (statusUtil.noXMLParsingErrorsOccurred(threshold)) {</span><br><span class=line> addInfo(<span class=string>"Registering current configuration as safe fallback point"</span>);</span><br><span class=line> registerSafeConfiguration(recorder.saxEventList);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>需要解析 xml 了,先是调用 <code>buildInterpreter</code> 构建了 Interpreter<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=keyword>void</span> <span class="title function_">doConfigure</span><span class=params>(<span class=keyword>final</span> List&LTSaxEvent> eventList)</span> <span class=keyword>throws</span> JoranException {</span><br><span class=line> buildInterpreter();</span><br><span class=line> <span class=comment>// disallow simultaneous configurations of the same context</span></span><br><span class=line> <span class=keyword>synchronized</span> (context.getConfigurationLock()) {</span><br><span class=line> interpreter.getEventPlayer().play(eventList);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>build 里还有一些逻辑,就是匹配后面要处理的规则集,就是要确认那些标签要处理<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> <span class=keyword>void</span> <span class="title function_">buildInterpreter</span><span class=params>()</span> {</span><br><span class=line> <span class=type>RuleStore</span> <span class=variable>rs</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">SimpleRuleStore</span>(context);</span><br><span class=line> addInstanceRules(rs);</span><br><span class=line> <span class=built_in>this</span>.interpreter = <span class=keyword>new</span> <span class="title class_">Interpreter</span>(context, rs, initialElementPath());</span><br><span class=line> <span class=type>InterpretationContext</span> <span class=variable>interpretationContext</span> <span class=operator>=</span> interpreter.getInterpretationContext();</span><br><span class=line> interpretationContext.setContext(context);</span><br><span class=line> addImplicitRules(interpreter);</span><br><span class=line> addDefaultNestedComponentRegistryRules(interpretationContext.getDefaultNestedComponentRegistry());</span><br><span class=line> }</span><br></pre></table></figure><p>第一步就是先 new 一个 <code>ch.qos.logback.core.joran.spi.SimpleRuleStore</code> 然后调用了 <code>ch.qos.logback.classic.joran.JoranConfigurator#addInstanceRules</code> 来添加规则,就是下面的,可以看到对于 logger,appender 这些的配置,其中前面点的父类也又一些规则 ,<code>ch.qos.logback.core.joran.JoranConfiguratorBase</code> 逻辑类似就不展开了,这里的规则就对应了后面的各种 Action,就是对应的处理逻辑<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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">addInstanceRules</span><span class=params>(RuleStore rs)</span> {</span><br><span class=line> <span class=comment>// parent rules already added</span></span><br><span class=line> <span class=built_in>super</span>.addInstanceRules(rs);</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration"</span>), <span class=keyword>new</span> <span class="title class_">ConfigurationAction</span>());</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/contextName"</span>), <span class=keyword>new</span> <span class="title class_">ContextNameAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/contextListener"</span>), <span class=keyword>new</span> <span class="title class_">LoggerContextListenerAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/insertFromJNDI"</span>), <span class=keyword>new</span> <span class="title class_">InsertFromJNDIAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/evaluator"</span>), <span class=keyword>new</span> <span class="title class_">EvaluatorAction</span>());</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/appender/sift"</span>), <span class=keyword>new</span> <span class="title class_">SiftAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/appender/sift/*"</span>), <span class=keyword>new</span> <span class="title class_">NOPAction</span>());</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/logger"</span>), <span class=keyword>new</span> <span class="title class_">LoggerAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/logger/level"</span>), <span class=keyword>new</span> <span class="title class_">LevelAction</span>());</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/root"</span>), <span class=keyword>new</span> <span class="title class_">RootLoggerAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/root/level"</span>), <span class=keyword>new</span> <span class="title class_">LevelAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/logger/appender-ref"</span>), <span class=keyword>new</span> <span class="title class_">AppenderRefAction</span>&LTILoggingEvent>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/root/appender-ref"</span>), <span class=keyword>new</span> <span class="title class_">AppenderRefAction</span>&LTILoggingEvent>());</span><br><span class=line></span><br><span class=line> <span class=comment>// add if-then-else support</span></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"*/if"</span>), <span class=keyword>new</span> <span class="title class_">IfAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"*/if/then"</span>), <span class=keyword>new</span> <span class="title class_">ThenAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"*/if/then/*"</span>), <span class=keyword>new</span> <span class="title class_">NOPAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"*/if/else"</span>), <span class=keyword>new</span> <span class="title class_">ElseAction</span>());</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"*/if/else/*"</span>), <span class=keyword>new</span> <span class="title class_">NOPAction</span>());</span><br><span class=line></span><br><span class=line> <span class=comment>// add jmxConfigurator only if we have JMX available.</span></span><br><span class=line> <span class=comment>// If running under JDK 1.4 (retrotranslateed logback) then we</span></span><br><span class=line> <span class=comment>// might not have JMX.</span></span><br><span class=line> <span class=keyword>if</span> (PlatformInfo.hasJMXObjectName()) {</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/jmxConfigurator"</span>), <span class=keyword>new</span> <span class="title class_">JMXConfiguratorAction</span>());</span><br><span class=line> }</span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/include"</span>), <span class=keyword>new</span> <span class="title class_">IncludeAction</span>());</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/consolePlugin"</span>), <span class=keyword>new</span> <span class="title class_">ConsolePluginAction</span>());</span><br><span class=line></span><br><span class=line> rs.addRule(<span class=keyword>new</span> <span class="title class_">ElementSelector</span>(<span class=string>"configuration/receiver"</span>), <span class=keyword>new</span> <span class="title class_">ReceiverAction</span>());</span><br><span class=line></span><br><span class=line>}</span><br></pre></table></figure><p>然后调用了 interpreter 的 eventPlayer 处理 xml 的各个标签<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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">play</span><span class=params>(List&LTSaxEvent> aSaxEventList)</span> {</span><br><span class=line> eventList = aSaxEventList;</span><br><span class=line> SaxEvent se;</span><br><span class=line> <span class=keyword>for</span> (currentIndex = <span class=number>0</span>; currentIndex < eventList.size(); currentIndex++) {</span><br><span class=line> se = eventList.get(currentIndex);</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (se <span class=keyword>instanceof</span> StartEvent) {</span><br><span class=line> interpreter.startElement((StartEvent) se);</span><br><span class=line> <span class=comment>// invoke fireInPlay after startElement processing</span></span><br><span class=line> interpreter.getInterpretationContext().fireInPlay(se);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (se <span class=keyword>instanceof</span> BodyEvent) {</span><br><span class=line> <span class=comment>// invoke fireInPlay before characters processing</span></span><br><span class=line> interpreter.getInterpretationContext().fireInPlay(se);</span><br><span class=line> interpreter.characters((BodyEvent) se);</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (se <span class=keyword>instanceof</span> EndEvent) {</span><br><span class=line> <span class=comment>// invoke fireInPlay before endElement processing</span></span><br><span class=line> interpreter.getInterpretationContext().fireInPlay(se);</span><br><span class=line> interpreter.endElement((EndEvent) se);</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>接下去就在 <code>startElement</code> 中调用会先获取 <code>getApplicableActionList</code> 适配的 Action, <code>callBeginAction</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></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=keyword>void</span> <span class="title function_">startElement</span><span class=params>(String namespaceURI, String localName, String qName, Attributes atts)</span> {</span><br><span class=line></span><br><span class=line> <span class=type>String</span> <span class=variable>tagName</span> <span class=operator>=</span> getTagName(localName, qName);</span><br><span class=line> elementPath.push(tagName);</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (skip != <span class=literal>null</span>) {</span><br><span class=line> <span class=comment>// every startElement pushes an action list</span></span><br><span class=line> pushEmptyActionList();</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> List&LTAction> applicableActionList = getApplicableActionList(elementPath, atts);</span><br><span class=line> <span class=keyword>if</span> (applicableActionList != <span class=literal>null</span>) {</span><br><span class=line> actionListStack.add(applicableActionList);</span><br><span class=line> callBeginAction(applicableActionList, tagName, atts);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=comment>// every startElement pushes an action list</span></span><br><span class=line> pushEmptyActionList();</span><br><span class=line> <span class=type>String</span> <span class=variable>errMsg</span> <span class=operator>=</span> <span class=string>"no applicable action for ["</span> + tagName + <span class=string>"], current ElementPath is ["</span> + elementPath + <span class=string>"]"</span>;</span><br><span class=line> cai.addError(errMsg);</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>里面就是用了 ruleStore 来判断是否适配,并且取出对应的 Action<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>List&LTAction> <span class="title function_">getApplicableActionList</span><span class=params>(ElementPath elementPath, Attributes attributes)</span> {</span><br><span class=line> List&LTAction> applicableActionList = ruleStore.matchActions(elementPath);</span><br><span class=line></span><br><span class=line> <span class=comment>// logger.debug("set of applicable patterns: " + applicableActionList);</span></span><br><span class=line> <span class=keyword>if</span> (applicableActionList == <span class=literal>null</span>) {</span><br><span class=line> applicableActionList = lookupImplicitAction(elementPath, attributes, interpretationContext);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=keyword>return</span> applicableActionList;</span><br><span class=line>}</span><br></pre></table></figure><p>比如我这边往下处理,通过规则匹配拿到了 LoggerAction, 然后调用 <code>Action.begin</code> 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><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>void</span> <span class="title function_">callBeginAction</span><span class=params>(List&LTAction> applicableActionList, String tagName, Attributes atts)</span> {</span><br><span class=line> <span class=keyword>if</span> (applicableActionList == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> Iterator&LTAction> i = applicableActionList.iterator();</span><br><span class=line> <span class=keyword>while</span> (i.hasNext()) {</span><br><span class=line> <span class=type>Action</span> <span class=variable>action</span> <span class=operator>=</span> (Action) i.next();</span><br><span class=line> <span class=comment>// now let us invoke the action. We catch and report any eventual</span></span><br><span class=line> <span class=comment>// exceptions</span></span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> action.begin(interpretationContext, tagName, atts);</span><br><span class=line> } <span class=keyword>catch</span> (ActionException e) {</span><br><span class=line> skip = elementPath.duplicate();</span><br><span class=line> cai.addError(<span class=string>"ActionException in Action for tag ["</span> + tagName + <span class=string>"]"</span>, e);</span><br><span class=line> } <span class=keyword>catch</span> (RuntimeException e) {</span><br><span class=line> skip = elementPath.duplicate();</span><br><span class=line> cai.addError(<span class=string>"RuntimeException in Action for tag ["</span> + tagName + <span class=string>"]"</span>, e);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>就是下面这个<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><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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>void</span> <span class="title function_">begin</span><span class=params>(InterpretationContext ec, String name, Attributes attributes)</span> {</span><br><span class=line> <span class=comment>// Let us forget about previous errors (in this object)</span></span><br><span class=line> inError = <span class=literal>false</span>;</span><br><span class=line> logger = <span class=literal>null</span>;</span><br><span class=line></span><br><span class=line> <span class=type>LoggerContext</span> <span class=variable>loggerContext</span> <span class=operator>=</span> (LoggerContext) <span class=built_in>this</span>.context;</span><br><span class=line></span><br><span class=line> <span class=type>String</span> <span class=variable>loggerName</span> <span class=operator>=</span> ec.subst(attributes.getValue(NAME_ATTRIBUTE));</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (OptionHelper.isEmpty(loggerName)) {</span><br><span class=line> inError = <span class=literal>true</span>;</span><br><span class=line> <span class=type>String</span> <span class=variable>aroundLine</span> <span class=operator>=</span> getLineColStr(ec);</span><br><span class=line> <span class=type>String</span> <span class=variable>errorMsg</span> <span class=operator>=</span> <span class=string>"No 'name' attribute in element "</span> + name + <span class=string>", around "</span> + aroundLine;</span><br><span class=line> addError(errorMsg);</span><br><span class=line> <span class=keyword>return</span>;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> logger = loggerContext.getLogger(loggerName);</span><br><span class=line></span><br><span class=line> <span class=type>String</span> <span class=variable>levelStr</span> <span class=operator>=</span> ec.subst(attributes.getValue(LEVEL_ATTRIBUTE));</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (!OptionHelper.isEmpty(levelStr)) {</span><br><span class=line> <span class=keyword>if</span> (ActionConst.INHERITED.equalsIgnoreCase(levelStr) || ActionConst.NULL.equalsIgnoreCase(levelStr)) {</span><br><span class=line> addInfo(<span class=string>"Setting level of logger ["</span> + loggerName + <span class=string>"] to null, i.e. INHERITED"</span>);</span><br><span class=line> logger.setLevel(<span class=literal>null</span>);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=type>Level</span> <span class=variable>level</span> <span class=operator>=</span> Level.toLevel(levelStr);</span><br><span class=line> addInfo(<span class=string>"Setting level of logger ["</span> + loggerName + <span class=string>"] to "</span> + level);</span><br><span class=line> logger.setLevel(level);</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=type>String</span> <span class=variable>additivityStr</span> <span class=operator>=</span> ec.subst(attributes.getValue(ActionConst.ADDITIVITY_ATTRIBUTE));</span><br><span class=line> <span class=keyword>if</span> (!OptionHelper.isEmpty(additivityStr)) {</span><br><span class=line> <span class=type>boolean</span> <span class=variable>additive</span> <span class=operator>=</span> OptionHelper.toBoolean(additivityStr, <span class=literal>true</span>);</span><br><span class=line> addInfo(<span class=string>"Setting additivity of logger ["</span> + loggerName + <span class=string>"] to "</span> + additive);</span><br><span class=line> logger.setAdditive(additive);</span><br><span class=line> }</span><br><span class=line> ec.pushObject(logger);</span><br><span class=line> }</span><br></pre></table></figure><p>这里就会处理 logger 获取逻辑<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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class=keyword>final</span> Logger <span class="title function_">getLogger</span><span class=params>(<span class=keyword>final</span> String name)</span> {</span><br><span class=line></span><br><span class=line> <span class=keyword>if</span> (name == <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">IllegalArgumentException</span>(<span class=string>"name argument cannot be null"</span>);</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// if we are asking for the root logger, then let us return it without</span></span><br><span class=line> <span class=comment>// wasting time</span></span><br><span class=line> <span class=keyword>if</span> (Logger.ROOT_LOGGER_NAME.equalsIgnoreCase(name)) {</span><br><span class=line> <span class=keyword>return</span> root;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=type>int</span> <span class=variable>i</span> <span class=operator>=</span> <span class=number>0</span>;</span><br><span class=line> <span class=type>Logger</span> <span class=variable>logger</span> <span class=operator>=</span> root;</span><br><span class=line></span><br><span class=line> <span class=comment>// check if the desired logger exists, if it does, return it</span></span><br><span class=line> <span class=comment>// without further ado.</span></span><br><span class=line> <span class=type>Logger</span> <span class=variable>childLogger</span> <span class=operator>=</span> (Logger) loggerCache.get(name);</span><br><span class=line> <span class=comment>// if we have the child, then let us return it without wasting time</span></span><br><span class=line> <span class=keyword>if</span> (childLogger != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>return</span> childLogger;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=comment>// if the desired logger does not exist, them create all the loggers</span></span><br><span class=line> <span class=comment>// in between as well (if they don't already exist)</span></span><br><span class=line> String childName;</span><br><span class=line> <span class=keyword>while</span> (<span class=literal>true</span>) {</span><br><span class=line> <span class=type>int</span> <span class=variable>h</span> <span class=operator>=</span> LoggerNameUtil.getSeparatorIndexOf(name, i);</span><br><span class=line> <span class=keyword>if</span> (h == -<span class=number>1</span>) {</span><br><span class=line> childName = name;</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> childName = name.substring(<span class=number>0</span>, h);</span><br><span class=line> }</span><br><span class=line> <span class=comment>// move i left of the last point</span></span><br><span class=line> i = h + <span class=number>1</span>;</span><br><span class=line> <span class=keyword>synchronized</span> (logger) {</span><br><span class=line> childLogger = logger.getChildByName(childName);</span><br><span class=line> <span class=keyword>if</span> (childLogger == <span class=literal>null</span>) {</span><br><span class=line> childLogger = logger.createChildByName(childName);</span><br><span class=line> loggerCache.put(childName, childLogger);</span><br><span class=line> incSize();</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> logger = childLogger;</span><br><span class=line> <span class=keyword>if</span> (h == -<span class=number>1</span>) {</span><br><span class=line> <span class=keyword>return</span> childLogger;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>如果从 <code>loggerCache</code> 中能取到就直接获取,如果不能就会去创建</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 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