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);
}
}
controller
@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