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class=post-content itemscope itemtype=http://schema.org/Article lang=zh-CN><link href=https://nicksxs.me/2023/12/17/Tomcat-%E7%B3%BB%E5%88%97%E7%AF%87%E5%8D%81%E4%BA%8C-%E7%95%AA%E5%A4%96%E4%BB%8B%E7%BB%8D%E4%B8%8B-Tomcat-%E7%9A%84%E4%B8%8A%E4%BC%A0%E6%96%87%E4%BB%B6%E9%99%90%E5%88%B6/ itemprop=mainEntityOfPage><span hidden itemprop=author itemscope itemtype=http://schema.org/Person><meta content=/uploads/avatar.jpg itemprop=image><meta content=Nicksxs itemprop=name></span><span hidden itemprop=publisher itemscope itemtype=http://schema.org/Organization><meta content="Nicksxs's Blog" itemprop=name><meta content="Nicksxs 的技术博客,深入 Java 运行时与生产诊断、低成本大模型推理和 Agent 工程实践。" itemprop=description></span><span hidden itemprop=post itemscope itemtype=http://schema.org/CreativeWork><meta content="Tomcat 系列篇十二-番外介绍下 Tomcat 的上传文件限制 | Nicksxs's Blog" itemprop=name><meta content="最近同学在把 springboot 升级到 2.x 版本的过程中碰到了小问题,可能升级变更里能找到信息,不过我们以学习为目的,可以看看代码是怎么样的 报错是在这段代码里的 org.apache.tomcat.util.http.fileupload.util.LimitedIn…" itemprop=description></span><header class=post-header><h1 itemprop="name headline" class=post-title>Tomcat 系列篇十二-番外介绍下 Tomcat 的上传文件限制</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:2023-12-17 19:17:52" datetime=2023-12-17T19:17:52+08:00>2023-12-17</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/SpringBoot/ itemprop=url rel=index><span itemprop=name>SpringBoot</span></a> </span>, <span itemprop=about itemscope itemtype=http://schema.org/Thing><a href=/categories/Java/SpringBoot/Tomcat/ itemprop=url rel=index><span itemprop=name>Tomcat</span></a> </span></span><span class="post-meta-item cloudflare-page-counter" data-title="Tomcat 系列篇十二-番外介绍下 Tomcat 的上传文件限制" data-increment=true data-path=/2023/12/17/Tomcat-%E7%B3%BB%E5%88%97%E7%AF%87%E5%8D%81%E4%BA%8C-%E7%95%AA%E5%A4%96%E4%BB%8B%E7%BB%8D%E4%B8%8B-Tomcat-%E7%9A%84%E4%B8%8A%E4%BC%A0%E6%96%87%E4%BB%B6%E9%99%90%E5%88%B6/ 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>最近同学在把 springboot 升级到 2.x 版本的过程中碰到了小问题,可能升级变更里能找到信息,不过我们以学习为目的,可以看看代码是怎么样的 报错是在这段代码里的 org.apache.tomcat.util.http.fileupload.util.LimitedIn…</div></div></header><div class=post-body itemprop=articleBody><p>最近同学在把 springboot 升级到 2.x 版本的过程中碰到了小问题,可能升级变更里能找到信息,不过我们以学习为目的,可以看看代码是怎么样的<br>报错是在这段代码里的<br><code>org.apache.tomcat.util.http.fileupload.util.LimitedInputStream#checkLimit</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>private</span> <span class=keyword>void</span> <span class="title function_">checkLimit</span><span class=params>()</span> <span class=keyword>throws</span> IOException {</span><br><span class=line> <span class=keyword>if</span> (count > sizeMax) {</span><br><span class=line> raiseError(sizeMax, count);</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>其中的 <code>raiseError</code> 是个抽象方法<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>protected</span> <span class=keyword>abstract</span> <span class=keyword>void</span> <span class="title function_">raiseError</span><span class=params>(<span class=type>long</span> pSizeMax, <span class=type>long</span> pCount)</span></span><br><span class=line> <span class=keyword>throws</span> IOException;</span><br></pre></table></figure><p>具体的实现是在<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></pre><td class=code><pre><span class=line><span class=keyword>public</span> <span class="title function_">FileItemStreamImpl</span><span class=params>(FileItemIteratorImpl pFileItemIterator, String pName, String pFieldName, String pContentType, <span class=type>boolean</span> pFormField, <span class=type>long</span> pContentLength)</span> <span class=keyword>throws</span> FileUploadException, IOException {</span><br><span class=line> <span class=built_in>this</span>.fileItemIteratorImpl = pFileItemIterator;</span><br><span class=line> <span class=built_in>this</span>.name = pName;</span><br><span class=line> <span class=built_in>this</span>.fieldName = pFieldName;</span><br><span class=line> <span class=built_in>this</span>.contentType = pContentType;</span><br><span class=line> <span class=built_in>this</span>.formField = pFormField;</span><br><span class=line> <span class=type>long</span> <span class=variable>fileSizeMax</span> <span class=operator>=</span> <span class=built_in>this</span>.fileItemIteratorImpl.getFileSizeMax();</span><br><span class=line> <span class=keyword>if</span> (fileSizeMax != -<span class=number>1L</span> && pContentLength != -<span class=number>1L</span> && pContentLength > fileSizeMax) {</span><br><span class=line> <span class=type>FileSizeLimitExceededException</span> <span class=variable>e</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">FileSizeLimitExceededException</span>(String.format(<span class=string>"The field %s exceeds its maximum permitted size of %s bytes."</span>, <span class=built_in>this</span>.fieldName, fileSizeMax), pContentLength, fileSizeMax);</span><br><span class=line> e.setFileName(pName);</span><br><span class=line> e.setFieldName(pFieldName);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">FileUploadIOException</span>(e);</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>final</span> MultipartStream.<span class=type>ItemInputStream</span> <span class=variable>itemStream</span> <span class=operator>=</span> <span class=built_in>this</span>.fileItemIteratorImpl.getMultiPartStream().newInputStream();</span><br><span class=line> <span class=type>InputStream</span> <span class=variable>istream</span> <span class=operator>=</span> itemStream;</span><br><span class=line> <span class=keyword>if</span> (fileSizeMax != -<span class=number>1L</span>) {</span><br><span class=line> istream = <span class=keyword>new</span> <span class="title class_">LimitedInputStream</span>(itemStream, fileSizeMax) {</span><br><span class=line> <span class=keyword>protected</span> <span class=keyword>void</span> <span class="title function_">raiseError</span><span class=params>(<span class=type>long</span> pSizeMax, <span class=type>long</span> pCount)</span> <span class=keyword>throws</span> IOException {</span><br><span class=line> itemStream.close(<span class=literal>true</span>);</span><br><span class=line> <span class=type>FileSizeLimitExceededException</span> <span class=variable>e</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">FileSizeLimitExceededException</span>(String.format(<span class=string>"The field %s exceeds its maximum permitted size of %s bytes."</span>, FileItemStreamImpl.<span class=built_in>this</span>.fieldName, pSizeMax), pCount, pSizeMax);</span><br><span class=line> e.setFieldName(FileItemStreamImpl.<span class=built_in>this</span>.fieldName);</span><br><span class=line> e.setFileName(FileItemStreamImpl.<span class=built_in>this</span>.name);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">FileUploadIOException</span>(e);</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=built_in>this</span>.stream = (InputStream)istream;</span><br><span class=line> }</span><br><span class=line> }</span><br></pre></table></figure><p>后面也会介绍到,这里我们其实主要是要找到这个 pSizeMax 是哪里来的<br>通过阅读代码会发现跟这个类 <code>MultipartConfigElement</code> 有关系<br>而在升级后的 springboot 中这个类已经有了自动装配类,也就是<br><code>org.springframework.boot.autoconfigure.web.servlet.MultipartAutoConfiguration</code><p>有了这个自动装配<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></pre><td class=code><pre><span class=line><span class=meta>@Configuration(</span></span><br><span class=line><span class=meta> proxyBeanMethods = false</span></span><br><span class=line><span class=meta>)</span></span><br><span class=line><span class=meta>@ConditionalOnClass({Servlet.class, StandardServletMultipartResolver.class, MultipartConfigElement.class})</span></span><br><span class=line><span class=meta>@ConditionalOnProperty(</span></span><br><span class=line><span class=meta> prefix = "spring.servlet.multipart",</span></span><br><span class=line><span class=meta> name = {"enabled"},</span></span><br><span class=line><span class=meta> matchIfMissing = true</span></span><br><span class=line><span class=meta>)</span></span><br><span class=line><span class=meta>@ConditionalOnWebApplication(</span></span><br><span class=line><span class=meta> type = Type.SERVLET</span></span><br><span class=line><span class=meta>)</span></span><br><span class=line><span class=meta>@EnableConfigurationProperties({MultipartProperties.class})</span></span><br><span class=line><span class=keyword>public</span> <span class=keyword>class</span> <span class="title class_">MultipartAutoConfiguration</span> {</span><br><span class=line> <span class=keyword>private</span> <span class=keyword>final</span> MultipartProperties multipartProperties;</span><br><span class=line></span><br><span class=line> <span class=keyword>public</span> <span class="title function_">MultipartAutoConfiguration</span><span class=params>(MultipartProperties multipartProperties)</span> {</span><br><span class=line> <span class=built_in>this</span>.multipartProperties = multipartProperties;</span><br><span class=line> }</span><br><span class=line></span><br><span class=line> <span class=meta>@Bean</span></span><br><span class=line> <span class=meta>@ConditionalOnMissingBean({MultipartConfigElement.class, CommonsMultipartResolver.class})</span></span><br><span class=line> <span class=keyword>public</span> MultipartConfigElement <span class="title function_">multipartConfigElement</span><span class=params>()</span> {</span><br><span class=line> <span class=keyword>return</span> <span class=built_in>this</span>.multipartProperties.createMultipartConfig();</span><br><span class=line> }</span><br></pre></table></figure><p>而这个 MultipartProperties 类中<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><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=meta>@ConfigurationProperties(</span></span><br><span class=line><span class=meta> prefix = "spring.servlet.multipart",</span></span><br><span class=line><span class=meta> ignoreUnknownFields = false</span></span><br><span class=line><span class=meta>)</span></span><br><span class=line><span class=keyword>public</span> <span class=keyword>class</span> <span class="title class_">MultipartProperties</span> {</span><br><span class=line> <span class=keyword>private</span> <span class=type>boolean</span> <span class=variable>enabled</span> <span class=operator>=</span> <span class=literal>true</span>;</span><br><span class=line> <span class=keyword>private</span> String location;</span><br><span class=line> <span class=keyword>private</span> <span class=type>DataSize</span> <span class=variable>maxFileSize</span> <span class=operator>=</span> DataSize.ofMegabytes(<span class=number>1L</span>);</span><br><span class=line> <span class=keyword>private</span> <span class=type>DataSize</span> <span class=variable>maxRequestSize</span> <span class=operator>=</span> DataSize.ofMegabytes(<span class=number>10L</span>);</span><br><span class=line> <span class=keyword>private</span> <span class=type>DataSize</span> <span class=variable>fileSizeThreshold</span> <span class=operator>=</span> DataSize.ofBytes(<span class=number>0L</span>);</span><br><span class=line> <span class=keyword>private</span> <span class=type>boolean</span> <span class=variable>resolveLazily</span> <span class=operator>=</span> <span class=literal>false</span>;</span><br></pre></table></figure><p>并且在前面 createMultipartConfig 中就使用了这个maxFileSize 的默认值<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> MultipartConfigElement <span class="title function_">createMultipartConfig</span><span class=params>()</span> {</span><br><span class=line> <span class=type>MultipartConfigFactory</span> <span class=variable>factory</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">MultipartConfigFactory</span>();</span><br><span class=line> <span class=type>PropertyMapper</span> <span class=variable>map</span> <span class=operator>=</span> PropertyMapper.get().alwaysApplyingWhenNonNull();</span><br><span class=line> map.from(<span class=built_in>this</span>.fileSizeThreshold).to(factory::setFileSizeThreshold);</span><br><span class=line> map.from(<span class=built_in>this</span>.location).whenHasText().to(factory::setLocation);</span><br><span class=line> map.from(<span class=built_in>this</span>.maxRequestSize).to(factory::setMaxRequestSize);</span><br><span class=line> map.from(<span class=built_in>this</span>.maxFileSize).to(factory::setMaxFileSize);</span><br><span class=line> <span class=keyword>return</span> factory.createMultipartConfig();</span><br><span class=line>}</span><br></pre></table></figure><p>而在 <code>org.apache.catalina.connector.Request#parseParts</code> 中,会判断 mce 的配置<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>private</span> <span class=keyword>void</span> <span class="title function_">parseParts</span><span class=params>(<span class=type>boolean</span> explicit)</span> {</span><br><span class=line></span><br><span class=line> <span class=comment>// 省略一部分代码</span></span><br><span class=line></span><br><span class=line> <span class=type>ServletFileUpload</span> <span class=variable>upload</span> <span class=operator>=</span> <span class=keyword>new</span> <span class="title class_">ServletFileUpload</span>();</span><br><span class=line> upload.setFileItemFactory(factory);</span><br><span class=line> upload.setFileSizeMax(mce.getMaxFileSize());</span><br><span class=line> upload.setSizeMax(mce.getMaxRequestSize());</span><br><span class=line></span><br><span class=line> parts = <span class=keyword>new</span> <span class="title class_">ArrayList</span><>();</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> List&LTFileItem> items =</span><br><span class=line> upload.parseRequest(<span class=keyword>new</span> <span class="title class_">ServletRequestContext</span>(<span class=built_in>this</span>));</span><br><span class=line> <span class=type>int</span> <span class=variable>maxPostSize</span> <span class=operator>=</span> getConnector().getMaxPostSize();</span><br><span class=line> <span class=type>int</span> <span class=variable>postSize</span> <span class=operator>=</span> <span class=number>0</span>;</span><br><span class=line> <span class=type>Charset</span> <span class=variable>charset</span> <span class=operator>=</span> getCharset();</span><br></pre></table></figure><p>主要 org.apache.tomcat.util.http.fileupload.FileUploadBase#parseRequest<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> List&LTFileItem> <span class="title function_">parseRequest</span><span class=params>(<span class=keyword>final</span> RequestContext ctx)</span></span><br><span class=line> <span class=keyword>throws</span> FileUploadException {</span><br><span class=line> <span class=keyword>final</span> List&LTFileItem> items = <span class=keyword>new</span> <span class="title class_">ArrayList</span><>();</span><br><span class=line> <span class=type>boolean</span> <span class=variable>successful</span> <span class=operator>=</span> <span class=literal>false</span>;</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItemIterator</span> <span class=variable>iter</span> <span class=operator>=</span> getItemIterator(ctx);</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItemFactory</span> <span class=variable>fileItemFactory</span> <span class=operator>=</span> Objects.requireNonNull(getFileItemFactory(),</span><br><span class=line> <span class=string>"No FileItemFactory has been set."</span>);</span><br><span class=line> <span class=keyword>final</span> <span class=type>byte</span>[] buffer = <span class=keyword>new</span> <span class="title class_">byte</span>[Streams.DEFAULT_BUFFER_SIZE];</span><br><span class=line> <span class=keyword>while</span> (iter.hasNext()) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItemStream</span> <span class=variable>item</span> <span class=operator>=</span> iter.next();</span><br><span class=line> <span class=comment>// Don't use getName() here to prevent an InvalidFileNameException.</span></span><br><span class=line> <span class=keyword>final</span> <span class=type>String</span> <span class=variable>fileName</span> <span class=operator>=</span> item.getName();</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItem</span> <span class=variable>fileItem</span> <span class=operator>=</span> fileItemFactory.createItem(item.getFieldName(), item.getContentType(),</span><br><span class=line> item.isFormField(), fileName);</span><br><span class=line> items.add(fileItem);</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> Streams.copy(item.openStream(), fileItem.getOutputStream(), <span class=literal>true</span>, buffer);</span><br><span class=line> } <span class=keyword>catch</span> (<span class=keyword>final</span> FileUploadIOException e) {</span><br></pre></table></figure><p>其中 org.apache.tomcat.util.http.fileupload.FileUploadBase#getItemIterator<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> FileItemIterator <span class="title function_">getItemIterator</span><span class=params>(<span class=keyword>final</span> RequestContext ctx)</span></span><br><span class=line><span class=keyword>throws</span> FileUploadException, IOException {</span><br><span class=line> <span class=keyword>try</span> {</span><br><span class=line> <span class=keyword>return</span> <span class=keyword>new</span> <span class="title class_">FileItemIteratorImpl</span>(<span class=built_in>this</span>, ctx);</span><br><span class=line> } <span class=keyword>catch</span> (<span class=keyword>final</span> FileUploadIOException e) {</span><br><span class=line> <span class=comment>// unwrap encapsulated SizeException</span></span><br><span class=line> <span class=keyword>throw</span> (FileUploadException) e.getCause();</span><br><span class=line> }</span><br><span class=line>}</span><br></pre></table></figure><p>这里就创建了 org.apache.tomcat.util.http.fileupload.impl.FileItemIteratorImpl<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> <span class="title function_">FileItemIteratorImpl</span><span class=params>(<span class=keyword>final</span> FileUploadBase fileUploadBase, <span class=keyword>final</span> RequestContext requestContext)</span></span><br><span class=line> <span class=keyword>throws</span> FileUploadException, IOException {</span><br><span class=line> <span class=built_in>this</span>.fileUploadBase = fileUploadBase;</span><br><span class=line> sizeMax = fileUploadBase.getSizeMax();</span><br><span class=line> fileSizeMax = fileUploadBase.getFileSizeMax();</span><br><span class=line> ctx = Objects.requireNonNull(requestContext, <span class=string>"requestContext"</span>);</span><br><span class=line> skipPreamble = <span class=literal>true</span>;</span><br><span class=line> findNextItem();</span><br><span class=line>}</span><br><span class=line></span><br></pre></table></figure><p>内部使用了前面给 upload 设置的文件大小上限 upload.setFileSizeMax(mce.getMaxFileSize());<p>然后在 findNextItem 里执行了初始化<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><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></pre><td class=code><pre><span class=line><span class=keyword>private</span> <span class=type>boolean</span> <span class="title function_">findNextItem</span><span class=params>()</span> <span class=keyword>throws</span> FileUploadException, IOException {</span><br><span class=line> <span class=keyword>if</span> (eof) {</span><br><span class=line> <span class=keyword>return</span> <span class=literal>false</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (currentItem != <span class=literal>null</span>) {</span><br><span class=line> currentItem.close();</span><br><span class=line> currentItem = <span class=literal>null</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>final</span> <span class=type>MultipartStream</span> <span class=variable>multi</span> <span class=operator>=</span> getMultiPartStream();</span><br><span class=line> <span class=keyword>for</span> (;;) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>boolean</span> nextPart;</span><br><span class=line> <span class=keyword>if</span> (skipPreamble) {</span><br><span class=line> nextPart = multi.skipPreamble();</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> nextPart = multi.readBoundary();</span><br><span class=line> }</span><br><span class=line> <span class=keyword>if</span> (!nextPart) {</span><br><span class=line> <span class=keyword>if</span> (currentFieldName == <span class=literal>null</span>) {</span><br><span class=line> <span class=comment>// Outer multipart terminated -> No more data</span></span><br><span class=line> eof = <span class=literal>true</span>;</span><br><span class=line> <span class=keyword>return</span> <span class=literal>false</span>;</span><br><span class=line> }</span><br><span class=line> <span class=comment>// Inner multipart terminated -> Return to parsing the outer</span></span><br><span class=line> multi.setBoundary(multiPartBoundary);</span><br><span class=line> currentFieldName = <span class=literal>null</span>;</span><br><span class=line> <span class=keyword>continue</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItemHeaders</span> <span class=variable>headers</span> <span class=operator>=</span> fileUploadBase.getParsedHeaders(multi.readHeaders());</span><br><span class=line> <span class=keyword>if</span> (currentFieldName == <span class=literal>null</span>) {</span><br><span class=line> <span class=comment>// We're parsing the outer multipart</span></span><br><span class=line> <span class=keyword>final</span> <span class=type>String</span> <span class=variable>fieldName</span> <span class=operator>=</span> fileUploadBase.getFieldName(headers);</span><br><span class=line> <span class=keyword>if</span> (fieldName != <span class=literal>null</span>) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>String</span> <span class=variable>subContentType</span> <span class=operator>=</span> headers.getHeader(FileUploadBase.CONTENT_TYPE);</span><br><span class=line> <span class=keyword>if</span> (subContentType != <span class=literal>null</span></span><br><span class=line> && subContentType.toLowerCase(Locale.ENGLISH)</span><br><span class=line> .startsWith(FileUploadBase.MULTIPART_MIXED)) {</span><br><span class=line> currentFieldName = fieldName;</span><br><span class=line> <span class=comment>// Multiple files associated with this field name</span></span><br><span class=line> <span class=keyword>final</span> <span class=type>byte</span>[] subBoundary = fileUploadBase.getBoundary(subContentType);</span><br><span class=line> multi.setBoundary(subBoundary);</span><br><span class=line> skipPreamble = <span class=literal>true</span>;</span><br><span class=line> <span class=keyword>continue</span>;</span><br><span class=line> }</span><br><span class=line> <span class=keyword>final</span> <span class=type>String</span> <span class=variable>fileName</span> <span class=operator>=</span> fileUploadBase.getFileName(headers);</span><br><span class=line> currentItem = <span class=keyword>new</span> <span class="title class_">FileItemStreamImpl</span>(<span class=built_in>this</span>, fileName,</span><br><span class=line> fieldName, headers.getHeader(FileUploadBase.CONTENT_TYPE),</span><br><span class=line> fileName == <span class=literal>null</span>, getContentLength(headers));</span><br><span class=line> currentItem.setHeaders(headers);</span><br><span class=line> progressNotifier.noteItem();</span><br><span class=line> itemValid = <span class=literal>true</span>;</span><br><span class=line> <span class=keyword>return</span> <span class=literal>true</span>;</span><br><span class=line> }</span><br><span class=line> } <span class=keyword>else</span> {</span><br><span class=line> <span class=keyword>final</span> <span class=type>String</span> <span class=variable>fileName</span> <span class=operator>=</span> fileUploadBase.getFileName(headers);</span><br><span class=line> <span class=keyword>if</span> (fileName != <span class=literal>null</span>) {</span><br><span class=line> currentItem = <span class=keyword>new</span> <span class="title class_">FileItemStreamImpl</span>(<span class=built_in>this</span>, fileName,</span><br><span class=line> currentFieldName,</span><br><span class=line> headers.getHeader(FileUploadBase.CONTENT_TYPE),</span><br><span class=line> <span class=literal>false</span>, getContentLength(headers));</span><br><span class=line> currentItem.setHeaders(headers);</span><br><span class=line> progressNotifier.noteItem();</span><br><span class=line> itemValid = <span class=literal>true</span>;</span><br><span class=line> <span class=keyword>return</span> <span class=literal>true</span>;</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line> multi.discardBodyData();</span><br><span class=line> }</span><br><span class=line> }</span><br><span class=line></span><br></pre></table></figure><p>这里面就会 new 这个 FileItemStreamImpl<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>currentItem = <span class=keyword>new</span> <span class="title class_">FileItemStreamImpl</span>(<span class=built_in>this</span>, fileName,</span><br><span class=line> fieldName, headers.getHeader(FileUploadBase.CONTENT_TYPE),</span><br><span class=line> fileName == <span class=literal>null</span>, getContentLength(headers));</span><br><span class=line></span><br></pre></table></figure><p>构造方法比较长<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="title function_">FileItemStreamImpl</span><span class=params>(<span class=keyword>final</span> FileItemIteratorImpl pFileItemIterator, <span class=keyword>final</span> String pName, <span class=keyword>final</span> String pFieldName,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> String pContentType, <span class=keyword>final</span> <span class=type>boolean</span> pFormField,</span></span><br><span class=line><span class=params> <span class=keyword>final</span> <span class=type>long</span> pContentLength)</span> <span class=keyword>throws</span> FileUploadException, IOException {</span><br><span class=line> fileItemIteratorImpl = pFileItemIterator;</span><br><span class=line> name = pName;</span><br><span class=line> fieldName = pFieldName;</span><br><span class=line> contentType = pContentType;</span><br><span class=line> formField = pFormField;</span><br><span class=line> <span class=keyword>final</span> <span class=type>long</span> <span class=variable>fileSizeMax</span> <span class=operator>=</span> fileItemIteratorImpl.getFileSizeMax();</span><br><span class=line> <span class=keyword>if</span> (fileSizeMax != -<span class=number>1</span> && pContentLength != -<span class=number>1</span></span><br><span class=line> && pContentLength > fileSizeMax) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileSizeLimitExceededException</span> <span class=variable>e</span> <span class=operator>=</span></span><br><span class=line> <span class=keyword>new</span> <span class="title class_">FileSizeLimitExceededException</span>(</span><br><span class=line> String.format(<span class=string>"The field %s exceeds its maximum permitted size of %s bytes."</span>,</span><br><span class=line> fieldName, Long.valueOf(fileSizeMax)),</span><br><span class=line> pContentLength, fileSizeMax);</span><br><span class=line> e.setFileName(pName);</span><br><span class=line> e.setFieldName(pFieldName);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">FileUploadIOException</span>(e);</span><br><span class=line> }</span><br><span class=line> <span class=comment>// OK to construct stream now</span></span><br><span class=line> <span class=keyword>final</span> <span class=type>ItemInputStream</span> <span class=variable>itemStream</span> <span class=operator>=</span> fileItemIteratorImpl.getMultiPartStream().newInputStream();</span><br><span class=line> <span class=type>InputStream</span> <span class=variable>istream</span> <span class=operator>=</span> itemStream;</span><br><span class=line> <span class=keyword>if</span> (fileSizeMax != -<span class=number>1</span>) {</span><br><span class=line> istream = <span class=keyword>new</span> <span class="title class_">LimitedInputStream</span>(istream, fileSizeMax) {</span><br><span class=line> <span class=meta>@Override</span></span><br><span class=line> <span class=keyword>protected</span> <span class=keyword>void</span> <span class="title function_">raiseError</span><span class=params>(<span class=keyword>final</span> <span class=type>long</span> pSizeMax, <span class=keyword>final</span> <span class=type>long</span> pCount)</span></span><br><span class=line> <span class=keyword>throws</span> IOException {</span><br><span class=line> itemStream.close(<span class=literal>true</span>);</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileSizeLimitExceededException</span> <span class=variable>e</span> <span class=operator>=</span></span><br><span class=line> <span class=keyword>new</span> <span class="title class_">FileSizeLimitExceededException</span>(</span><br><span class=line> String.format(<span class=string>"The field %s exceeds its maximum permitted size of %s bytes."</span>,</span><br><span class=line> fieldName, Long.valueOf(pSizeMax)),</span><br><span class=line> pCount, pSizeMax);</span><br><span class=line> e.setFieldName(fieldName);</span><br><span class=line> e.setFileName(name);</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">FileUploadIOException</span>(e);</span><br><span class=line> }</span><br><span class=line> };</span><br><span class=line> }</span><br><span class=line> stream = istream;</span><br><span class=line> }</span><br></pre></table></figure><p>当 <code>fileSizeMax != 0</code> 的时候就会初始化 LimitedInputStream,这就就是会在前面的<p><code>org.apache.tomcat.util.http.fileupload.FileUploadBase#parseRequest</code> 中<figure class="highlight java"><table><tr><td class=gutter><pre><span class=line>1</span><br></pre><td class=code><pre><span class=line>Streams.copy(item.openStream(), fileItem.getOutputStream(), <span class=literal>true</span>, buffer);</span><br></pre></table></figure><p>这里的 item<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>final</span> <span class=type>FileItemIterator</span> <span class=variable>iter</span> <span class=operator>=</span> getItemIterator(ctx);</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItemFactory</span> <span class=variable>fileItemFactory</span> <span class=operator>=</span> Objects.requireNonNull(getFileItemFactory(),</span><br><span class=line> <span class=string>"No FileItemFactory has been set."</span>);</span><br><span class=line> <span class=keyword>final</span> <span class=type>byte</span>[] buffer = <span class=keyword>new</span> <span class="title class_">byte</span>[Streams.DEFAULT_BUFFER_SIZE];</span><br><span class=line> <span class=keyword>while</span> (iter.hasNext()) {</span><br><span class=line> <span class=keyword>final</span> <span class=type>FileItemStream</span> <span class=variable>item</span> <span class=operator>=</span> iter.next();</span><br></pre></table></figure><p>调用了 FileItemIterator 迭代器的 next<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></pre><td class=code><pre><span class=line><span class=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> FileItemStream <span class="title function_">next</span><span class=params>()</span> <span class=keyword>throws</span> FileUploadException, IOException {</span><br><span class=line> <span class=keyword>if</span> (eof || (!itemValid && !hasNext())) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">NoSuchElementException</span>();</span><br><span class=line> }</span><br><span class=line> itemValid = <span class=literal>false</span>;</span><br><span class=line> <span class=keyword>return</span> currentItem;</span><br><span class=line> }</span><br></pre></table></figure><p>这个 <code>currentItem</code> 就是前面 new 的 FileItemStreamImpl<p>然后在 Streams.copy 的时候调用 openStream 也就是 <code>org.apache.tomcat.util.http.fileupload.impl.FileItemStreamImpl#openStream</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=meta>@Override</span></span><br><span class=line> <span class=keyword>public</span> InputStream <span class="title function_">openStream</span><span class=params>()</span> <span class=keyword>throws</span> IOException {</span><br><span class=line> <span class=keyword>if</span> (((Closeable) stream).isClosed()) {</span><br><span class=line> <span class=keyword>throw</span> <span class=keyword>new</span> <span class="title class_">FileItemStream</span>.ItemSkippedException();</span><br><span class=line> }</span><br><span class=line> <span class=keyword>return</span> stream;</span><br><span class=line> }</span><br></pre></table></figure><p>这里的 stream 就是 FileItemStreamImpl 构造方法最后赋值的 stream,会在大小超过限制时抛出错误<p>而这个可以通过设置 properties 来修改,spring.servlet.multipart.max-file-size 和 spring.servlet.multipart.max-request-size<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>spring.servlet.multipart.max-file-size=100MB</span><br><span class=line>spring.servlet.multipart.max-request-size=100MB</span><br></pre></table></figure><p>而老版本的 <code>spring.http.multipart.maxFileSize</code><br>其实就是配置名称改了下,但是能看一下代码也是有点收获的。</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 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