Spring中向服务器上传图片需要进行配置bean CommonsMultipartResolver；具体配置如下：
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> <!-- 默认编码 (ISO-8859-1) --> <property name="defaultEncoding" value="UTF-8"/> <!-- 最大内存大小 (10240) --> <property name="maxInMemorySize" value="10240"/> <!-- 上传后的目录名 --> <!--<property name="uploadTempDir" value="/upload"/>--> <!-- 最大文件大小，-1为无限止(-1),最大上传文件3M --> <property name="maxUploadSize" value="3000000"/> </bean>
上面的配置中可以看到设置的文件上传的大小限制为3M；当上传的文件的大小超过上限时，便会抛出MaxUploadSizeExceededException异常。
今天遇到的最大的问题便是：如何优雅的处理MaxUploadSizeExceededException异常？
MaxUploadSizeExceededException异常的特殊之处在于，当上传文件的大小超过限制时，它的抛出并是在进入Controller之前，所以不能在controller中利用注解@ExceptionHandler（MaxUploadSizeExceededException.class）来定义该异常的处理方法；
经过网上的搜索，出了利用filter以为，还看到其它三种处理办法：
1.在xml中配置SimpleMappingExceptionResolver，其中加入对MaxUploadSizeExceededException异常的处理，指定对应的错误页面，具体如下：
<!-- 全局异常处理 -->
<bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver"> <property name="exceptionMappings"> <props> <!-- 处理超过大小时的异常 --> <!--遇到MaxUploadSizeExceededException异常时，自动跳转到/WEB-INF/views/errors/upload.jsp页面 --> <prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">errors/upload</prop> </props> </property> </bean>
2.将对应的controller实现HandlerExceptionResolver接口，然后重写其中的resolveException方法，返回ModelAndView，用于对MaxUploadSizeExceededException进行处理，具体如下：
@Controller
public class FileUploadController implements HandlerExceptionResolver { /*** Trap Exceptions during the upload and show errors back in view form ***/ public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object handler, Exception exception) { Map<String, Object> model = new HashMap<String, Object>(); if (exception instanceof MaxUploadSizeExceededException) { model.put("errors", exception.getMessage()); } else { model.put("errors", "Unexpected error: " + exception.getMessage()); } model.put("uploadedFile", new UploadedFile()); return new ModelAndView("/upload", model); } }
3.继承CommonsMultipartResolver类，重写parseRequest方法，在其中对MaxUploadSizeExceededException异常信息进行处理，放入request中，在controller再进行相应ModelAndView的返回，具体如下：
public class DropOversizeFilesMultipartResolver extends CommonsMultipartResolver { @Override protected MultipartParsingResult parseRequest(final HttpServletRequest request) { String encoding = determineEncoding(request); FileUpload fileUpload = prepareFileUpload(encoding); List fileItems; try { fileItems = ((ServletFileUpload) fileUpload).parseRequest(request); } catch (FileUploadBase.SizeLimitExceededException ex) { request.setAttribute(EXCEPTION_KEY, ex); fileItems = Collections.EMPTY_LIST; } catch (FileUploadException ex) { throw new MultipartException("Could not parse multipart servlet request", ex); } return parseFileItems(fileItems, encoding); } }
@InitBinder("fileForm")
protected void initBinderDesignForm(WebDataBinder binder) { binder.setValidator(new FileFormValidator()); } @RequestMapping(value = "/my/mapping", method = RequestMethod.POST) public ModelAndView acceptFile(HttpServletRequest request, Model model, FormData formData, BindingResult result) { Object exception = request.getAttribute(DropOversizeFilesMultipartResolver.EXCEPTION_KEY); if (exception != null && FileUploadBase.SizeLimitExceededException.class.equals(exception.getClass())) { result.rejectValue("file", "<your.message.key>"); LOGGER.error(exception); }
以上三种方法都能够类似实现返回一个ModelAndView来实现对MaxUploadSizeExceededException进行处理；
http://stackoverflow.com/questions/2689989/how-to-handle-maxuploadsizeexceededexception
http://stackoverflow.com/questions/4029583/using-spring-3-exceptionhandler-with-commons-fileupload-and-sizelimitexceededex