使用@ControllerAdvice如何返回给前端对应错误码

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发布于 2022-03-29 06:36:01

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@ControllerAdvice可以捕获spring应用下面未被捕获异常，下面是常见代码：

    @ExceptionHandler(value = Exception.class)
     @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
     public String errorHandler(Exception ex) {
         ApiResultVo<String> resultVo = new ApiResultVo<>();
         resultVo.setErrorCode(500);
         resultVo.setErrorMsg(ex.getMessage());
         return JSON.toJSONString(resultVo);
     }
 
     @ExceptionHandler(value = MyException.class)
     @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
     public String myExceptionHandler(MyException ex) {
         ApiResultVo<String> resultVo = new ApiResultVo<>();
         resultVo.setErrorCode(401);
         resultVo.setErrorMsg(ex.getMessage());
         return JSON.toJSONString(resultVo);
     }

我们在对应异常处理的上面加上ResponseStatus注解就能将系统异常转换为对应的Http状态码，这部分工作由ResponseStatusExceptionResolver这个类完成，下面是关键代码：

    protected ModelAndView doResolveException(HttpServletRequest request, HttpServletResponse response,
             Object handler, Exception ex) {
        ResponseStatus responseStatus = AnnotatedElementUtils.findMergedAnnotation(ex.getClass(), ResponseStatus.class);
         if (responseStatus != null) {
             try {
                 return resolveResponseStatus(responseStatus, request, response, handler, ex);
             }
             catch (Exception resolveEx) {
                 logger.warn("Handling of @ResponseStatus resulted in Exception", resolveEx);
             }
         }
         else if (ex.getCause() instanceof Exception) {
             ex = (Exception) ex.getCause();
             return doResolveException(request, response, handler, ex);
         }
         return null;
     }
    protected ModelAndView resolveResponseStatus(ResponseStatus responseStatus, HttpServletRequest request,
             HttpServletResponse response, Object handler, Exception ex) throws Exception {
        int statusCode = responseStatus.code().value();
         String reason = responseStatus.reason();
         if (!StringUtils.hasLength(reason)) {
 response.sendError(statusCode);
         }
         else {
             String resolvedReason = (this.messageSource != null ?
                     this.messageSource.getMessage(reason, null, reason, LocaleContextHolder.getLocale()) :
                     reason);
             response.sendError(statusCode, resolvedReason);
         }
         return new ModelAndView();
     }