@RestControllerAdvice
public class GlobalExceptionHandler {

    /**
     * 前端請求的資料為json型別，後臺校驗失敗，出現的異常
     * org.springframework.web.bind.MethodArgumentNotValidException
     */
    @ExceptionHandler(value = {MethodArgumentNotValidException.class})
    public AjaxResult jsonErrorHandler(MethodArgumentNotValidException e) {
        return getAjaxResult(e.getBindingResult());
    }

    /**
     * 前端請求的資料為表單物件，後臺校驗失敗，出現的異常
     * org.springframework.validation.BindException
     */
    @ExceptionHandler(value = {BindException.class})
    public AjaxResult bindException(BindException e) {
        return getAjaxResult(e.getBindingResult());
    }

    /**
     * 獲得異常資訊
     * @param bindingResult
     * @return
     */
    private AjaxResult getAjaxResult(BindingResult bindingResult) {
        List<ObjectError> allErrors = bindingResult.getAllErrors();
        List<Map<String, Object>> messages = new ArrayList<>(allErrors.size());
        for (ObjectError allError : allErrors) {
            Map<String, Object> map = new HashMap<>();
            FieldError error = (FieldError) allError;
            map.put("objectName", error.getObjectName());
            map.put("defaultMessage", error.getDefaultMessage());
            map.put("field", error.getField());
            messages.add(map);
        }
        return AjaxResult.fail("後端資料校驗異常", messages);
    }
}