xml方式配置异常处理器

异常处理器：

当控制器方法出现指定异常（非指定异常）的时候，返回一个modelandview对象给dispatcherServlet

spring默认的异常处理器：

defaultExceptionResolver，已注册到ioc，出现异常时dispatcherServlet默认调用该异常处理器，处理包含的所有异常类型

protected ModelAndView doResolveException(
      HttpServletRequest request, HttpServletResponse response, @Nullable Object handler, Exception ex) {
?
   try {
      if (ex instanceof HttpRequestMethodNotSupportedException) {
         return handleHttpRequestMethodNotSupported(
               (HttpRequestMethodNotSupportedException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMediaTypeNotSupportedException) {
         return handleHttpMediaTypeNotSupported(
               (HttpMediaTypeNotSupportedException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMediaTypeNotAcceptableException) {
         return handleHttpMediaTypeNotAcceptable(
               (HttpMediaTypeNotAcceptableException) ex, request, response, handler);
      }
      else if (ex instanceof MissingPathVariableException) {
         return handleMissingPathVariable(
               (MissingPathVariableException) ex, request, response, handler);
      }
      else if (ex instanceof MissingServletRequestParameterException) {
         return handleMissingServletRequestParameter(
               (MissingServletRequestParameterException) ex, request, response, handler);
      }
      else if (ex instanceof ServletRequestBindingException) {
         return handleServletRequestBindingException(
               (ServletRequestBindingException) ex, request, response, handler);
      }
      else if (ex instanceof ConversionNotSupportedException) {
         return handleConversionNotSupported(
               (ConversionNotSupportedException) ex, request, response, handler);
      }
      else if (ex instanceof TypeMismatchException) {
         return handleTypeMismatch(
               (TypeMismatchException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMessageNotReadableException) {
         return handleHttpMessageNotReadable(
               (HttpMessageNotReadableException) ex, request, response, handler);
      }
      else if (ex instanceof HttpMessageNotWritableException) {
         return handleHttpMessageNotWritable(
               (HttpMessageNotWritableException) ex, request, response, handler);
      }
      else if (ex instanceof MethodArgumentNotValidException) {
         return handleMethodArgumentNotValidException(
               (MethodArgumentNotValidException) ex, request, response, handler);
      }
      else if (ex instanceof MissingServletRequestPartException) {
         return handleMissingServletRequestPartException(
               (MissingServletRequestPartException) ex, request, response, handler);
      }
      else if (ex instanceof BindException) {
         return handleBindException((BindException) ex, request, response, handler);
      }
      else if (ex instanceof NoHandlerFoundException) {
         return handleNoHandlerFoundException(
               (NoHandlerFoundException) ex, request, response, handler);
      }
      else if (ex instanceof AsyncRequestTimeoutException) {
         return handleAsyncRequestTimeoutException(
               (AsyncRequestTimeoutException) ex, request, response, handler);
      }
   }
   catch (Exception handlerEx) {
      if (logger.isWarnEnabled()) {
         logger.warn("Failure while trying to resolve exception [" + ex.getClass().getName() + "]", handlerEx);
      }
   }
   return null;
}

自定义的异常处理器：

SampleMappingExceptionResolver,需要注册到ioc中，控制器方法出现指定的异常时，由dispatcherServlet调用

    
                  要指定要处理的异常
    
               

          以ex（自定义）为键，以错误为值，将该键值对共享到Request域对象中