2023-09-14  阅读(79)
原文作者:王伟王胖胖 原文地址: https://blog.csdn.net/wangwei19871103/article/details/105572634

基本处理流程图

202309142305056811.png

通常的异常处理

我们来演示下,看看通常异常是怎么处理的,我们什么都不加,只是这样,看看内部怎么处理的:

202309142305065592.png
运行:

202309142305071753.png
运行到这里的时候直接抛异常:

202309142305078074.png
doDispatch方法中会保存异常。

202309142305088385.png
然后处理结果:

202309142305097316.png
走有异常的逻辑:

202309142305105267.png
进行异常解析器解析,DefaultErrorAttributes只是添加了异常属性,什么都没做:

202309142305118278.png
HandlerExceptionResolverComposite是一个异常解析器的符合解析器,里面有解析器处理。

202309142305128939.png

是否能解析异常

ExceptionHandlerExceptionResolver的shouldApplyTo

一般只解析HandlerMethod处理器类型的异常,刚好我们就是这个类型的处理器。

2023091423051392510.png
最终到AbstractHandlerExceptionResolvershouldApplyTo,我们没有映射的处理器来处理,所以全部为空的话也是返回true,表示可以处理:

2023091423051654511.png

doResolveHandlerMethodException处理

如果没有设置异常处理方法就返回null了,等于没处理,其实这里的方法是可以自定义的,后面说。

2023091423051766512.png

ResponseStatusExceptionResolver的处理

这个也是AbstractHandlerExceptionResolvershouldApplyTo,最终也是没处理:

2023091423051934213.png

DefaultHandlerExceptionResolver的处理

这个也是AbstractHandlerExceptionResolvershouldApplyTo,但是最后还是没处理,不过他已经判断了很多中异常了:

    @Override
    	@Nullable
    	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;
    	}

默认的异常处理都处理不了我这个异常java.lang.ArithmeticException: / by zero,然后就抛到tomcat里去了,我们后面说。

好了,今天就到这里了,希望对学习理解有帮助,大神看见勿喷,仅为自己的学习理解,能力有限,请多包涵。

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