springMVC笔记系列(21)——springMVC自带的上传文件功能实现

蔚落 2022-07-14 08:21 206阅读 0赞

说明：本文章的内容转载至：[https://my.oschina.net/happyBKs/blog/420310][https_my.oschina.net_happyBKs_blog_420310]  
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springMVC为我们提供了上传文件的内部支持，我们只需要一些配置，然后就可以借助于sprinngMVC提供给我们的接口完成文件上传的工作。

首选找到与springMVC的前端控制器DispatchServlet相关的上下文，即\\WEB-INF\\configs\\spring\\mvc-dispatcher-servlet.xml

在DispatchServlet的上下文中配置一个类型为org.springframework.web.multipart.commons.CommonsMultipartResolver的bean。

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
            <property name="maxUploadSize" value="209715200"/>
            <property name="defaultEncoding" value="UTF-8"/>
            <property name="resolveLazily" value="true"/>
        </bean>

这个bean专门用来为我们解析上载的文件。这个bean可以配置三个属性：

maxUploadSize设置文件上传的大小上限，单位是Byte，所以200MB这种记得自己算好算数哦。

defaultEncoding是默认编码，这里我们用的是UTF-8。

resolveLazily是延迟加载，这个设置为true，主要是为了提高性能，在需要的时候再进行解析。

我们从这个类的类型名称中带有的Common前缀可以看出，它依赖了apache的jar包，是的，事实就是如此。因此，我们需要在POM.xml中加入jar。

<dependency>
          <groupId>commons-fileupload</groupId>
          <artifactId>commons-fileupload</artifactId>
          <version>1.3.1</version>
        </dependency>

顺便提一下，这个jar包所依赖的commons-io的jar包也会自动加载，无须在pom中显示引入commons-io坐标。

![这里写图片描述][100529_jVZ9_1156339.png]

然后我们现在设计一个上传案例：

我们设计请求localhost:8080/mvc/courses/upload

因此控制器类中添加一个方法：

@RequestMapping(value="/upload", method=RequestMethod.GET)
        public String showUploadPage(){
            return "course_admin/file";
        }

然后，我们添加对应的JSP文件\\WEB-INF\\jsps\\course\_admin\\file.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
    
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>HappyBKs Upload Page</title>
    
        <link rel="stylesheet" href="<%=request.getContextPath()%>/resources/css/main.css" type="text/css" />
    </head>
    <body>
    <div align="center">
    
        <h1>上传附件</h1>
        <form method="post" action="/courses/doUpload" enctype="multipart/form-data">
            <input type="file" name="file"/>
            <input type="submit"/>
        </form>
    </div>
    </body>
    </html>

该页面的表单中包含了一个file类型的input和一个submit按钮，另外一个值得注意的是，form本身与一般的表单相比在这里须要额外添加一个属性enctype=”multipart/form-data”，这是我们在文件上传时所必须显示指明的属性，没有这个属性将无法完成文件上传工作。

这个表单提交后请求的url是localhost:8080/mvc/courses/doUpload，方法当然是POST。

因此，我们须要继续为这个请求再创建一个控制器方法来响应这个URL请求。在之前就说了，springMVC在进行相应的配置之后，就可以通过springMVC提供的一些接口来完成上载文件功能的编程实践：

@RequestMapping(value="/doUpload", method=RequestMethod.POST)
        public String doUploadFile(@RequestParam("file") MultipartFile file) throws IOException {
    
            if(!file.isEmpty()){
                log.info("Process file(getOriginalFilename): {}", file.getOriginalFilename());
                log.info("Process file(getName): {}", file.getName());
                log.info("Process file(getContentType): {}", file.getContentType());
                log.info("Process file(getSize): {}", file.getSize());
                FileUtils.copyInputStreamToFile(file.getInputStream(), new File("c:\\temp\\happyBKs\\", System.currentTimeMillis()+ file.getOriginalFilename()));
            }
    
            return "success";
        }

这个接口是一个类——org.springframework.web.multipart.MultipartFile。

springMVC的源代码中的接口定义接口如下：

package org.springframework.web.multipart;
    
    import java.io.File;
    import java.io.IOException;
    import java.io.InputStream;
    
    import org.springframework.core.io.InputStreamSource;
    
    /**
     * A representation of an uploaded file received in a multipart request.
     *
     * <p>The file contents are either stored in memory or temporarily on disk.
     * In either case, the user is responsible for copying file contents to a
     * session-level or persistent store as and if desired. The temporary storages
     * will be cleared at the end of request processing.
     *
     * @author Juergen Hoeller
     * @author Trevor D. Cook
     * @since 29.09.2003
     * @see org.springframework.web.multipart.MultipartHttpServletRequest
     * @see org.springframework.web.multipart.MultipartResolver
     */
    public interface MultipartFile extends InputStreamSource {
    
        /**
         * Return the name of the parameter in the multipart form.
         * @return the name of the parameter (never {@code null} or empty)
         */
        String getName();
    
        /**
         * Return the original filename in the client's filesystem.
         * <p>This may contain path information depending on the browser used,
         * but it typically will not with any other than Opera.
         * @return the original filename, or the empty String if no file
         * has been chosen in the multipart form, or {@code null}
         * if not defined or not available
         */
        String getOriginalFilename();
    
        /**
         * Return the content type of the file.
         * @return the content type, or {@code null} if not defined
         * (or no file has been chosen in the multipart form)
         */
        String getContentType();
    
        /**
         * Return whether the uploaded file is empty, that is, either no file has
         * been chosen in the multipart form or the chosen file has no content.
         */
        boolean isEmpty();
    
        /**
         * Return the size of the file in bytes.
         * @return the size of the file, or 0 if empty
         */
        long getSize();
    
        /**
         * Return the contents of the file as an array of bytes.
         * @return the contents of the file as bytes, or an empty byte array if empty
         * @throws IOException in case of access errors (if the temporary store fails)
         */
        byte[] getBytes() throws IOException;
    
        /**
         * Return an InputStream to read the contents of the file from.
         * The user is responsible for closing the stream.
         * @return the contents of the file as stream, or an empty stream if empty
         * @throws IOException in case of access errors (if the temporary store fails)
         */
        @Override
        InputStream getInputStream() throws IOException;
    
        /**
         * Transfer the received file to the given destination file.
         * <p>This may either move the file in the filesystem, copy the file in the
         * filesystem, or save memory-held contents to the destination file.
         * If the destination file already exists, it will be deleted first.
         * <p>If the file has been moved in the filesystem, this operation cannot
         * be invoked again. Therefore, call this method just once to be able to
         * work with any storage mechanism.
         * <p><strong>Note:</strong> when using Servlet 3.0 multipart support you
         * need to configure the location relative to which files will be copied
         * as explained in {@link javax.servlet.http.Part#write}.
         * @param dest the destination file
         * @throws IOException in case of reading or writing errors
         * @throws IllegalStateException if the file has already been moved
         * in the filesystem and is not available anymore for another transfer
         */
        void transferTo(File dest) throws IOException, IllegalStateException;
    
    }

这个接口实现的类对象可以获得文件的本地文件名、内容类型、大小等信息。

那么控制器的方法参数MultipartFile如何与请求提交的表单元素相关联呢？POST请求的表单元素是一种请求参数，建立请求参数与控制器方法参数之间的映射关联，当然用的是注解@RequestParam，如上面的控制器方法代码所示。这里@RequestParam(“file”)的值“file”与请求提交的表单中form的中的name=”file”名称对应，这样表单中name是file的元素的值就绑定到了控制器方法参数上，它的类型会被转换成MultipartFile，整个复杂的转换过程都由springMVC我们完成，我们自己要做的仅仅是使用这个留给我们的接口MultipartFile。

这里，我们还将MultipartFile的各个属性也一并输出到日志。

值得注意的是，实际的文件处理用了FileUtils来处理文件的相关操作，这是commons-io中十分有用的工具类，来完成文件的拷贝、文件流的操作等。

public static void copyInputStreamToFile(InputStream source, File destination) throws IOException

FileUtils.copyInputStreamToFile方法用于拷贝文件，第一个参数是拷贝文件源的流，正好MultipartFile有一个获取输入流的方法file.getInputStream()。输出的文件流，新建一个本地服务器的文件流，本地文件名是一个时间戳加上MultipartFile的原本的文件名。

我们继续为上传成功后转发的页面进行添加\\WEB-INF\\jsps\\success.jsp：

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8" %>
    <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
    <html>
    <head>
        <link rel="stylesheet" href="<%=request.getContextPath()%>/resources/css/main.css" type="text/css"/>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <title>Insert title here</title>
    </head>
    <body>
    <div align="center">
        <h1>Success!</h1>
    </div>
    </body>
    </html>

接下来，看看实际的运行效果：

请求[http://localhost:8080/mvc/courses/upload][http_localhost_8080_mvc_courses_upload]  
![这里写图片描述][153907_Rto3_1156339.png]  
选择一个图片文件好了  
![这里写图片描述][154040_coQz_1156339.png]

提交之后，POST请求带着表单数据请求：  
![这里写图片描述][154535_bJpH_1156339.png]

通过这个日志输出可以看到:

getOriginalFilename是得到文件自己的名字

getName是得到请求提交的表单中的元素名字

getContentType得到的是文件的类型

getSize得到文件的大小

之后控制器将请求处理之后，转向\\WEB-INF\\jsps\\success.jsp

![这里写图片描述][155155_qpfq_1156339.png]

本地服务器存储的位置也出现了相应的图片文件，命名方法就是我们自己定义的方式，带时间戳哦。  
![这里写图片描述][155318_zJi3_1156339.png]

好，假如我现在上传个超大文件，比如dota2的压缩安装文件：  
![这里写图片描述][155429_phZk_1156339.png]  
![这里写图片描述][155447_srF8_1156339.png]  
提交之后，服务就崩溃了：

![这里写图片描述][160111_w7Aa_1156339.png]

控制台输出以下错误：

654431 [http-apr-8080-exec-5] WARN  org.springframework.web.multipart.commons.CommonsMultipartResolver  - Failed to perform multipart cleanup for servlet request
    org.springframework.web.multipart.MaxUploadSizeExceededException: Maximum upload size of 209715200 bytes exceeded; nested exception is org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:162)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver$1.initializeMultipart(CommonsMultipartResolver.java:134)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getMultipartFiles(AbstractMultipartHttpServletRequest.java:126)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getMultiFileMap(AbstractMultipartHttpServletRequest.java:106)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.cleanupMultipart(CommonsMultipartResolver.java:191)
        at org.springframework.web.servlet.DispatcherServlet.cleanupMultipart(DispatcherServlet.java:1107)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2476)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2465)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:965)
        at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:310)
        at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:334)
        at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:158)
        ... 33 more
    654431 [http-apr-8080-exec-5] WARN  org.springframework.web.multipart.commons.CommonsMultipartResolver  - Failed to perform multipart cleanup for servlet request
    org.springframework.web.multipart.MaxUploadSizeExceededException: Maximum upload size of 209715200 bytes exceeded; nested exception is org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:162)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver$1.initializeMultipart(CommonsMultipartResolver.java:134)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getMultipartFiles(AbstractMultipartHttpServletRequest.java:126)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getMultiFileMap(AbstractMultipartHttpServletRequest.java:106)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.cleanupMultipart(CommonsMultipartResolver.java:191)
        at org.springframework.web.servlet.DispatcherServlet.cleanupMultipart(DispatcherServlet.java:1107)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2476)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2465)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:965)
        at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:310)
        at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:334)
        at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:158)
        ... 33 more
    654439 [http-apr-8080-exec-5] DEBUG org.springframework.web.servlet.DispatcherServlet  - Could not complete request
    org.springframework.web.multipart.MaxUploadSizeExceededException: Maximum upload size of 209715200 bytes exceeded; nested exception is org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:162)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver$1.initializeMultipart(CommonsMultipartResolver.java:134)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getMultipartFiles(AbstractMultipartHttpServletRequest.java:126)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getFile(AbstractMultipartHttpServletRequest.java:85)
        at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.resolveName(RequestParamMethodArgumentResolver.java:169)
        at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:90)
        at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:99)
        at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2476)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2465)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:965)
        at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:310)
        at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:334)
        at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:158)
        ... 40 more
    654439 [http-apr-8080-exec-5] DEBUG org.springframework.web.servlet.DispatcherServlet  - Could not complete request
    org.springframework.web.multipart.MaxUploadSizeExceededException: Maximum upload size of 209715200 bytes exceeded; nested exception is org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:162)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver$1.initializeMultipart(CommonsMultipartResolver.java:134)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getMultipartFiles(AbstractMultipartHttpServletRequest.java:126)
        at org.springframework.web.multipart.support.AbstractMultipartHttpServletRequest.getFile(AbstractMultipartHttpServletRequest.java:85)
        at org.springframework.web.method.annotation.RequestParamMethodArgumentResolver.resolveName(RequestParamMethodArgumentResolver.java:169)
        at org.springframework.web.method.annotation.AbstractNamedValueMethodArgumentResolver.resolveArgument(AbstractNamedValueMethodArgumentResolver.java:90)
        at org.springframework.web.method.support.HandlerMethodArgumentResolverComposite.resolveArgument(HandlerMethodArgumentResolverComposite.java:99)
        at org.springframework.web.method.support.InvocableHandlerMethod.getMethodArgumentValues(InvocableHandlerMethod.java:161)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:128)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:110)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:832)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:743)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:85)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:961)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:895)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:967)
        at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:869)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:843)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:957)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:423)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1079)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:620)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.doRun(AprEndpoint.java:2476)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoint.java:2465)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
    Caused by: org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (9686027054) exceeds the configured maximum (209715200)
        at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:965)
        at org.apache.commons.fileupload.FileUploadBase.getItemIterator(FileUploadBase.java:310)
        at org.apache.commons.fileupload.FileUploadBase.parseRequest(FileUploadBase.java:334)
        at org.apache.commons.fileupload.servlet.ServletFileUpload.parseRequest(ServletFileUpload.java:115)
        at org.springframework.web.multipart.commons.CommonsMultipartResolver.parseRequest(CommonsMultipartResolver.java:158)
        ... 40 more

这个异常应该如何捕获呢，虽然这种异常不会怎样，也确实证明了springMVC的这个上载文件的组件可以完成对文件大小的限制，但是如何才能捕获这个异常呢？

不要妄想直接在控制器类中捕获，因为，如果直接按照刚才的配置和代码，文件过大抛出异常时，根本就没有到/mvc/courses/doUpload对应的控制器方法doUploadFile就已经结束了。不信，我们做个实验：

我在方法的开始增加一句日志输出：

@RequestMapping(value="/doUpload", method=RequestMethod.POST)
        public String doUploadFile(@RequestParam("file") MultipartFile file) throws IOException {
    
            log.info("step into doUploadFile............................");
            if(!file.isEmpty()){
                log.info("Process file(getOriginalFilename): {}", file.getOriginalFilename());
                log.info("Process file(getName): {}", file.getName());
                log.info("Process file(getContentType): {}", file.getContentType());
                log.info("Process file(getSize): {}", file.getSize());
                FileUtils.copyInputStreamToFile(file.getInputStream(), new File("c:\\temp\\happyBKs\\", System.currentTimeMillis()+ file.getOriginalFilename()));
            }
    
            return "success";
        }

但是当我像刚才一样上载超大文件，提交表单之后，并没有输出过  
“step into doUploadFile……………………….”，也就是说，抛出上载文件过大异常时，程序根本没有进入控制器方法的执行体。那么该怎么办呢？

我们须要单独为控制器写一个处理异常的方法，用到注解@ExceptionHandler。

@ExceptionHandler(Exception.class)
        public void handleException(Exception ex,HttpServletRequest request,HttpServletResponse response){
            log.info("step into handleException............................");
            StringBuffer sb = new StringBuffer();
            sb.append("<script language='javascript'>history.go(-1);alert('");
            if (ex instanceof org.springframework.web.multipart.MaxUploadSizeExceededException){
                sb.append("文件大小不应大于"+((MaxUploadSizeExceededException)ex).getMaxUploadSize()/1000+"kb");
            } else{
                sb.append("上传异常！");
            }
            sb.append("！');</script>");
            try {
                System.out.println(sb.toString());
                response.setContentType("text/html; charset=utf-8");
                response.getWriter().println(sb.toString());
                response.getWriter().flush();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return;
        }

当按照刚才的方法上载大文件时，这时候，依然会抛出异常，但是，方法已经可以捕获了并采取措施了：日志输出如下：  
![这里写图片描述][181331_MBFN_1156339.png]  
好吧，我前端不在行，也懒得弄了，本来是想把这个用浏览器对话框输出的，不过验证了异常能够侦测到并实现相应的操作就已经达到目的了。但是，这里有个令人不解的地方是，我使用IE/EDGE浏览器会出现异常无法抛出的卡死现象，webkit系列的浏览器都能够抛出异常并继续执行异常处理的方法体。

[https_my.oschina.net_happyBKs_blog_420310]: https://my.oschina.net/happyBKs/blog/420310
[100529_jVZ9_1156339.png]: /images/20220714/a506972eb96b434b87745b2cb8f53e9b.png
[http_localhost_8080_mvc_courses_upload]: http://localhost:8080/mvc/courses/upload
[153907_Rto3_1156339.png]: /images/20220714/523f30bb660c4fe99ffc1270953c866e.png
[154040_coQz_1156339.png]: /images/20220714/d2cb1aa5a0f64dbb9568b1c6e1c647e3.png
[154535_bJpH_1156339.png]: /images/20220714/9a7adf9ee5e140dab06b470c7f5618a4.png
[155155_qpfq_1156339.png]: /images/20220714/c5c83398e71f421fb5b15dff58a57e43.png
[155318_zJi3_1156339.png]: /images/20220714/60950d74229542fbb81d85c9ba874f33.png
[155429_phZk_1156339.png]: /images/20220714/09ae6530267847fe998e022783998e75.png
[155447_srF8_1156339.png]: /images/20220714/daba32a0bbbe4d2485621a4e6855436e.png
[160111_w7Aa_1156339.png]: /images/20220714/4db19eeedec24a879fc242761254c634.png
[181331_MBFN_1156339.png]: /images/20220714/6b5544b2995248d5acecb9fd0e1ad66a.png