覆盖标准Spring MVC异常的处理行为

Question

Spring Boot似乎有一个默认行为来处理某些异常.我有一个休息控制器.如果我没有HttpRequestMethodNotSupportedException在带@ControllerAdvice注释的rest控制器中处理,则应用程序返回包含错误消息的默认JSON响应.

我不想替换这个JSON响应,但我确实希望在发生时记录其他信息(例如记录某个请求者的IP地址).

有没有办法用带@ExceptionHandler注释的方法或其他机制来做到这一点？

Answer 1

Spring MVC确实为您配置了异常处理程序.
默认情况下,DefaultHandlerExceptionResolver使用类javadoc中所述:

HandlerExceptionResolver解决标准Spring异常的接口的默认实现,并将它们转换为相应的HTTP状态代码.

默认情况下,在常见的Spring中启用此异常解析程序 org.springframework.web.servlet.DispatcherServlet.

在通过使用注释类定义自定义异常处理程序时ResponseEntityExceptionHandler,可以扩展默认的异常处理程序,例如ModelAndView.
并且您可以知道ReponseEntity在@ControllerAdvice类的facade方法的方法中实际处理的所有异常:

/**
 * Provides handling for standard Spring MVC exceptions.
 * @param ex the target exception
 * @param request the current request
 */
@ExceptionHandler({
        HttpRequestMethodNotSupportedException.class,
        HttpMediaTypeNotSupportedException.class,
        HttpMediaTypeNotAcceptableException.class,
        MissingPathVariableException.class,
        MissingServletRequestParameterException.class,
        ServletRequestBindingException.class,
        ConversionNotSupportedException.class,
        TypeMismatchException.class,
        HttpMessageNotReadableException.class,
        HttpMessageNotWritableException.class,
        MethodArgumentNotValidException.class,
        MissingServletRequestPartException.class,
        BindException.class,
        NoHandlerFoundException.class,
        AsyncRequestTimeoutException.class
    })
@Nullable
public final ResponseEntity<Object> handleException(Exception ex, WebRequest request) {
    HttpHeaders headers = new HttpHeaders();
    if (ex instanceof HttpRequestMethodNotSupportedException) {
        HttpStatus status = HttpStatus.METHOD_NOT_ALLOWED;
        return handleHttpRequestMethodNotSupported((HttpRequestMethodNotSupportedException) ex, headers, status, request);
    }
    else if (ex instanceof HttpMediaTypeNotSupportedException) {
        HttpStatus status = HttpStatus.UNSUPPORTED_MEDIA_TYPE;
        return handleHttpMediaTypeNotSupported((HttpMediaTypeNotSupportedException) ex, headers, status, request);
    }
    else if (ex instanceof HttpMediaTypeNotAcceptableException) {
        HttpStatus status = HttpStatus.NOT_ACCEPTABLE;
        return handleHttpMediaTypeNotAcceptable((HttpMediaTypeNotAcceptableException) ex, headers, status, request);
    }
    else if (ex instanceof MissingPathVariableException) {
        HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
        return handleMissingPathVariable((MissingPathVariableException) ex, headers, status, request);
    }
    else if (ex instanceof MissingServletRequestParameterException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleMissingServletRequestParameter((MissingServletRequestParameterException) ex, headers, status, request);
    }
    else if (ex instanceof ServletRequestBindingException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleServletRequestBindingException((ServletRequestBindingException) ex, headers, status, request);
    }
    else if (ex instanceof ConversionNotSupportedException) {
        HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
        return handleConversionNotSupported((ConversionNotSupportedException) ex, headers, status, request);
    }
    else if (ex instanceof TypeMismatchException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleTypeMismatch((TypeMismatchException) ex, headers, status, request);
    }
    else if (ex instanceof HttpMessageNotReadableException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleHttpMessageNotReadable((HttpMessageNotReadableException) ex, headers, status, request);
    }
    else if (ex instanceof HttpMessageNotWritableException) {
        HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
        return handleHttpMessageNotWritable((HttpMessageNotWritableException) ex, headers, status, request);
    }
    else if (ex instanceof MethodArgumentNotValidException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleMethodArgumentNotValid((MethodArgumentNotValidException) ex, headers, status, request);
    }
    else if (ex instanceof MissingServletRequestPartException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleMissingServletRequestPart((MissingServletRequestPartException) ex, headers, status, request);
    }
    else if (ex instanceof BindException) {
        HttpStatus status = HttpStatus.BAD_REQUEST;
        return handleBindException((BindException) ex, headers, status, request);
    }
    else if (ex instanceof NoHandlerFoundException) {
        HttpStatus status = HttpStatus.NOT_FOUND;
        return handleNoHandlerFoundException((NoHandlerFoundException) ex, headers, status, request);
    }
    else if (ex instanceof AsyncRequestTimeoutException) {
        HttpStatus status = HttpStatus.SERVICE_UNAVAILABLE;
        return handleAsyncRequestTimeoutException(
                (AsyncRequestTimeoutException) ex, headers, status, request);
    }
    else {
        if (logger.isWarnEnabled()) {
            logger.warn("Unknown exception type: " + ex.getClass().getName());
        }
        HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
        return handleExceptionInternal(ex, null, headers, status, request);
    }
}   

现在,如何覆盖特定异常的异常处理程序？Spring不允许您@ControllerAdvice在注释的方法中定义多个类的类ResponseEntityExceptionHandler.所以在自定义异常处理程序中添加此映射:

@ExceptionHandler(value = { HttpRequestMethodNotSupportedException.class })
protected ResponseEntity<Object> handleConflict(HttpRequestMethodNotSupportedException ex, WebRequest request) {
   ...
}

将无法正常工作:它将阻止Spring容器成功启动.
你应该得到一个例外,例如:

Caused by: java.lang.IllegalStateException: Ambiguous @ExceptionHandler method mapped for [class org.springframework.web.HttpRequestMethodNotSupportedException]: {protected org.springframework...

为了允许客户端子类覆盖实际定义的行为,Spring ResponseEntityExceptionHandler在handleException()基类的方法中实现了自己捕获和处理的每个异常的逻辑.
所以在你的情况下,你只需要覆盖ResponseEntityExceptionHandler我们可以在这里调用的内容:

if (ex instanceof HttpRequestMethodNotSupportedException) {
    HttpStatus status = HttpStatus.METHOD_NOT_ALLOWED;
    return handleHttpRequestMethodNotSupported((HttpRequestMethodNotSupportedException) ex, headers, status, request);
}

例如 :

@ControllerAdvice
public class MyExceptionHandler extends ResponseEntityExceptionHandler {

    @Override
    protected ResponseEntity<Object> handleHttpRequestMethodNotSupported(HttpRequestMethodNotSupportedException ex, HttpHeaders headers, HttpStatus status,
            WebRequest request) {    
        // do your processing
         ...
        // go on (or no) executing the logic defined in the base class 
        return super.handleHttpRequestMethodNotSupported(ex, headers, status, request);
    }
}