Spring MVC 文件上传的MaxUploadSizeExceededException异常处理

spring MVC上传文件使用了common.fileupload组件,该组件上传文件的时候有个文件大小的限制,在超出这个限制之后.会抛出MaxUploadSizeExceededException异常.

该异常是spring检查上传文件的信息的时候抛出的,此时还没进入Controller内解析文件的方法中.

网上查到的方法是:

1 使用org.springframework.web.servlet.handler.SimpleMappingExceptionResolver,如:

 <bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
     <property name="exceptionMappings">
    <props>
         <prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">error/maxUploadExceeded</prop>
    </props>
 </property>

个人更赞成这种方式，因为multipartResolver通常是全局使用的，指定的maxUploadSize通常也是全局的，这里应该配置一个全局异常处理来响应。

2  自己实现.HandlerExceptionResolver类,如

 public class MyHandlerExceptionResolver implements HandlerExceptionResolver {
     private Log log = LogFactory.getLog(getClass());
     public ModelAndView resolveException(HttpServletRequest request,
             HttpServletResponse response, Object handler, Exception ex) {
         log.warn("Handle exception: " + ex.getClass().getName());

         Map model = new HashMap();
         model.put("ex", ex.getClass().getSimpleName());
         model.put("error", ex.getMessage());
         return new ModelAndView("error", model);
     }

另定义<bean class="MyHandlerExceptionResolver "/>

这两种方法的侵入性真的太大了,查看源代码org.springframework.web.multipart.commons.CommonsMultipartResolver 127行

 if (this.resolveLazily) {
             return new DefaultMultipartHttpServletRequest(request) {
                 @Override
                 protected void initializeMultipart() {
                     MultipartParsingResult parsingResult = parseRequest(request);
                     setMultipartFiles(parsingResult.getMultipartFiles());
                     setMultipartParameters(parsingResult.getMultipartParameters());
                 }
             };
         }

有个resolveLazily属性,一个类似懒加载的属性.可以定义该属性.让解析文件的时候再抛异常,然后Controller中定义异常处理的方法

 <bean id="multipartResolver"
         class="org.springframework.web.multipart.commons.CommonsMultipartResolver"
         p:defaultEncoding="utf-8" >
       <property name="resolveLazily" value="true"/>
       <property name="maxUploadSize" value="1024" />
     </bean>

定义异常处理的方法

/**
     * 异常处理
     * @param ex
     * @param request
     * @Description:
     */
    @ExceptionHandler(Exception.class)
    public void handleException(Exception ex,HttpServletRequest request,HttpServletResponse response){
        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;
    }

 @ExceptionHandler(Exception.class)
     public String handleException(Exception ex,HttpServletRequest request) {
         if(ex instanceof org.springframework.web.multipart.MaxUploadSizeExceededException){
             request.setAttribute("error", "文件超过长度");
         }
         return "要转向的页面,可以自由定义或者是原页面.";
     }