json - Spring MVC中HandlerExceptionResolver的resolveException方法如何返回JSON对象？

Question

在 Spring MVC 中实现文件 uploader Controller 时，我遇到了一个问题。我的代码快照如下。

@Controller
public class FileUploader extends AbstractBaseController implements HandlerExceptionResolver
{
    @RequestMapping(value = "/uploadFile", method = RequestMethod.POST)
    @ResponseBody
    public JSONObject handleFileUpload(@RequestParam("file") MultipartFile file)
    {
        JSONObject returnObj = new JSONObject();
        if (file.isEmpty())
        {
            returnObj.put("success", "false");
            returnObj.put("message", "File is empty");
        }
        else
        {
            try
            {
                //my file upload logic goes here 
            }
            catch (Exception e)
            {
                returnObj.put("success", "false");
                returnObj.put("message", "File not uploaded.");
            }
        }

        return returnObj;
    }

    @Override
    public ModelAndView resolveException(HttpServletRequest request, HttpServletResponse response, Object obj, Exception exception)
    {
        ModelAndView model = new ModelAndView();
        Map map = new HashMap();
        if (exception instanceof MaxUploadSizeExceededException)
        {
            // I want to return JSONObject from here like given below.
            /**
             * { "message":"File size exceeded", "success":"false" }
             * */
            map.put("message", "File size exceeded");
            map.put("success", "false");
            model.addObject(map);
        }
        return model;
    }
}

我的 spring 配置看起来像

<bean id="multipartResolver"
    class="org.springframework.web.multipart.commons.CommonsMultipartResolver" >
    <property name="maxUploadSize" value="300000"/>
    </bean>

现在在我的 Controller 中，我想在我的 Controller 的 resolveException 方法中返回 JSONObject 而不是 ModelAndView，如代码快照中给出的那样，因为我正在开发一些类似 REST 的方法来上传文件。

有什么想法吗？谢谢

Answer 1

如果你使用上面的Spring 3.2，我推荐这种方式。

1. 首先，声明ControllerAdvice。

   @Controller
   @ControllerAdvice
   public class JAttachfileApi extends BaseApi
   

2. 并使异常处理程序响应如下 JSON 对象。

       @ExceptionHandler(MaxUploadSizeExceededException.class)
       public @ResponseBody Map<String,Object> handleMaxUploadSizeExceededException(
    MaxUploadSizeExceededException ex) 
       {
   
           Map<String,Object> result = getResult();
   
           JFileUploadJsonResponse errorResult = new JFileUploadJsonResponse();
           errorResult.setError("Maximum upload size of "+ex.getMaxUploadSize()+" bytes exceeded.");
           List<JFileUploadJsonResponse> resultData = new ArrayList<JFileUploadJsonResponse>();
           resultData.add(errorResult);
           result.put("files", resultData);
   
         return result;
       }