用来记录一些原创性的总结
ResponseEntityExceptionHandler中包装了各种SpringMVC在处理请求时可能抛出的异常的处理，处理结果都是封装成一个ResponseEntity对象。通过ResponseEntity我们可以指定需要响应的状态码、header和body等信息，响应的body会被HttpMessageConverter处理，所以如果你响应的body是一个对象，而你的HttpMessageConverter列表中有一个是可以把对象转换为JSON的HttpMessageConverter，那么客户端收到的就是一段JSON。ResponseEntityExceptionHandler是一个抽象类，通常我们需要定义一个用来处理异常的使用@ControllerAdvice注解标注的异常处理类来继承自ResponseEntityExceptionHandler。以下是ResponseEntityExceptionHandler的源码，从源码中我们可以看出它可以处理的异常，并为每个异常的处理都单独定义了一个方法，如果默认的处理不能满足你的需求，则可以重写对某个异常的处理。默认的实现最终都会调用handleExceptionInternal()方法，如果有通用的处理也可以从这里入手。
public abstract class ResponseEntityExceptionHandler {
protected final Log logger = LogFactory.getLog(getClass());
public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound";
protected static final Log pageNotFoundLogger = LogFactory.getLog(PAGE_NOT_FOUND_LOG_CATEGORY);
@ExceptionHandler(value={
NoSuchRequestHandlingMethodException.class,
HttpRequestMethodNotSupportedException.class,
HttpMediaTypeNotSupportedException.class,
HttpMediaTypeNotAcceptableException.class,
MissingServletRequestParameterException.class,
ServletRequestBindingException.class,
ConversionNotSupportedException.class,
TypeMismatchException.class,
HttpMessageNotReadableException.class,
HttpMessageNotWritableException.class,
MethodArgumentNotValidException.class,
MissingServletRequestPartException.class,
BindException.class,
NoHandlerFoundException.class
})
public final ResponseEntity<Object> handleException(Exception ex, WebRequest request) {
HttpHeaders headers = new HttpHeaders();
if (ex instanceof NoSuchRequestHandlingMethodException) {
HttpStatus status = HttpStatus.NOT_FOUND;
return handleNoSuchRequestHandlingMethod((NoSuchRequestHandlingMethodException) ex, headers, status, request);
}
else 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 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 {
logger.warn("Unknown exception type: " + ex.getClass().getName());
HttpStatus status = HttpStatus.INTERNAL_SERVER_ERROR;
return handleExceptionInternal(ex, null, headers, status, request);
}
}
/**
* A single place to customize the response body of all Exception types.
* This method returns {@code null} by default.
* @param ex the exception
* @param body the body to use for the response
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
*/
protected ResponseEntity<Object> handleExceptionInternal(Exception ex, Object body,
HttpHeaders headers, HttpStatus status, WebRequest request) {
if (HttpStatus.INTERNAL_SERVER_ERROR.equals(status)) {
request.setAttribute("javax.servlet.error.exception", ex, WebRequest.SCOPE_REQUEST);
}
return new ResponseEntity<Object>(body, headers, status);
}
/**
* Customize the response for NoSuchRequestHandlingMethodException.
* This method logs a warning and delegates to
* {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleNoSuchRequestHandlingMethod(NoSuchRequestHandlingMethodException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
pageNotFoundLogger.warn(ex.getMessage());
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for HttpRequestMethodNotSupportedException.
* This method logs a warning, sets the "Allow" header, and delegates to
* {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleHttpRequestMethodNotSupported(HttpRequestMethodNotSupportedException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
pageNotFoundLogger.warn(ex.getMessage());
Set<HttpMethod> supportedMethods = ex.getSupportedHttpMethods();
if (!supportedMethods.isEmpty()) {
headers.setAllow(supportedMethods);
}
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for HttpMediaTypeNotSupportedException.
* This method sets the "Accept" header and delegates to
* {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleHttpMediaTypeNotSupported(HttpMediaTypeNotSupportedException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
List<MediaType> mediaTypes = ex.getSupportedMediaTypes();
if (!CollectionUtils.isEmpty(mediaTypes)) {
headers.setAccept(mediaTypes);
}
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for HttpMediaTypeNotAcceptableException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleHttpMediaTypeNotAcceptable(HttpMediaTypeNotAcceptableException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for MissingServletRequestParameterException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleMissingServletRequestParameter(MissingServletRequestParameterException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for ServletRequestBindingException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleServletRequestBindingException(ServletRequestBindingException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for ConversionNotSupportedException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleConversionNotSupported(ConversionNotSupportedException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for TypeMismatchException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleTypeMismatch(TypeMismatchException ex, HttpHeaders headers,
HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for HttpMessageNotReadableException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleHttpMessageNotReadable(HttpMessageNotReadableException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for HttpMessageNotWritableException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleHttpMessageNotWritable(HttpMessageNotWritableException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for MethodArgumentNotValidException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleMethodArgumentNotValid(MethodArgumentNotValidException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for MissingServletRequestPartException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleMissingServletRequestPart(MissingServletRequestPartException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for BindException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
*/
protected ResponseEntity<Object> handleBindException(BindException ex, HttpHeaders headers,
HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
/**
* Customize the response for NoHandlerFoundException.
* This method delegates to {@link #handleExceptionInternal(Exception, Object, HttpHeaders, HttpStatus, WebRequest)}.
* @param ex the exception
* @param headers the headers to be written to the response
* @param status the selected response status
* @param request the current request
* @return a {@code ResponseEntity} instance
* @since 4.0
*/
protected ResponseEntity<Object> handleNoHandlerFoundException(NoHandlerFoundException ex, HttpHeaders headers,
HttpStatus status, WebRequest request) {
return handleExceptionInternal(ex, null, headers, status, request);
}
}
比如下面实现中就重写了handleHttpRequestMethodNotSupported()方法。
@ControllerAdvice
public class MyResponseEntityExceptionHandler extends ResponseEntityExceptionHandler {
@Override
protected ResponseEntity<Object> handleHttpRequestMethodNotSupported(HttpRequestMethodNotSupportedException ex,
HttpHeaders headers, HttpStatus status, WebRequest request) {
String method = ex.getMethod();
String[] supportedMethods = ex.getSupportedMethods();
String body = "不支持的请求类型：" + method + "，支持的请求类型：" + Arrays.toString(supportedMethods);
Map<String, Object> map = new HashMap<>();
map.put("body", body);
return super.handleExceptionInternal(ex, body, headers, status, request);
}
}
（注：本文是基于Spring4.1.0所写）