Spring MVC Controller返回值及异常的统一处理方法

Spring MVC Controller返回值及异常的统一处理方法

旧的设计方案

开发api的时候,需要先定义好接口的数据响应结果.如下是一个很简单直接的Controller实现方法及响应结果定义.

@RestController

@RequestMapping("/users")

public class UserController {

@Inject

private UserService userService;

@GetRequest("/{userId:\\d+}")

public ResponseBean signin(@PathVariable long userId) {

try {

User user = userService.getUserBaseInfo(userId);

return ResponseBean.success(user);

} catch (ServiceException e) {

return new ReponseBean(e.getCode(), e.getMsg());

} catch (Exception e) {

return ResponseBean.systemError();

}

}

}

{

code: "",

data: {}, // 可以是对象或者数组

msg: ""

}

从上面的代码，我们可以看到对于每个 Controller 方法，都会有很多重复的代码出现，我们应该设法去避免重复的代码。将重复的代码移除之后，可以得到如下的代码，简单易懂。

@RestController

@RequestMapping("/users")

public class UserController {

@Inject

private UserService userService;

@GetRequest("/{userId:\\d+}")

public User signin(@PathVariable long userId) {

return userService.getUserBaseInfo(userId);

}

}

在以上的实现中，还做了一个必要的要求，就是 ServiceException 需要定义为 RuntimeException的子类，而不是 Exception的子类。由于 ServiceException 表示服务异常，一般发生这种异常是应该直接提示前端，而无需进行其他特殊处理的。在定义为 RuntimeException 的子类之后，会减少大量的异常抛出声明，而且不再需要在事务@Transactional 中进行特殊声明。

统一 Controller 返回值格式

在开发的过程中，我发现上面的结构

@ControllerAdvice

public class ControllerResponseHandler implements ResponseBodyAdvice

private Logger logger = LogManager.getLogger(getClass());

@Override

public boolean supports(MethodParameter returnType, Class extends HttpMessageConverter>> converterType) {

// 支持所有的返回值类型

return true;

}

@Override

public Object beforeBodyWrite(Object body, MethodParameter returnType, MediaType selectedContentType,

Class extends HttpMessageConverter>> selectedConverterType, ServerHttpRequest request,

ServerHttpResponse response) {

if(body instanceof ResponseBean) {

return body;

} else {

// 所有没有返回　ResponseBean　结构的结果均认为是成功的

return ResponseBean.success(body);

}

}

}

统一异常处理

如下的代码中，ServiceException ServiceMessageException ValidatorErrorType FieldValidatorError 均为自定义类。

@ControllerAdvice

public class ControllerExceptionHandler {

private Logger logger = LogManager.getLogger(getClass());

private static final String logExceptionFormat = "[EXIGENCE] Some thing wrong with the system: %s";

/**

* 自定义异常

*/

@ExceptionHandler(ServiceMessageException.class)

public ResponseBean handleServiceMessageException(HttpServletRequest request, ServiceMessageException ex) {

logger.debug(ex);

return new ResponseBean(ex.getMsgCode(), ex.getMessage());

}

/**

* 自定义异常

*/

@ExceptionHandler(ServiceException.class)

public ResponseBean handleServiceException(HttpServletRequest request, ServiceException ex) {

logger.debug(ex);

String message = codeToMessage(ex.getMsgCode());

return new ResponseBean(ex.getMsgCode(), message);

}

/**

* MethodArgumentNotValidException: 实体类属性校验不通过

* 如: listUsersValid(@RequestBody @Valid UserFilterOption option)

*/

@ExceptionHandler(MethodArgumentNotValidException.class)

public ResponseBean handleMethodArgumentNotValid(HttpServletRequest request, MethodArgumentNotValidException ex) {

logger.debug(ex);

return validatorErrors(ex.getBindingResult());

}

private ResponseBean validatorErrors(BindingResult result) {

List errors = new ArrayList();

for (FieldError error : result.getFieldErrors()) {

errors.add(toFieldValidatorError(error));

}

return ResponseBean.validatorError(errors);

}

/**

* ConstraintViolationException: 直接对方法参数进行校验，校验不通过。

* 如: pageUsers(@RequestParam @Min(1)int pageIndex, @RequestParam @Max(100)int pageSize)

*/

@ExceptionHandler(ConstraintViolationException.class)

public ResponseBean handleConstraintViolationException(HttpServletRequest request,

ConstraintViolationException ex) {

logger.debug(ex);

//

List errors = new ArrayList();

for (ConstraintViolation> violation : ex.getConstraintViolations()) {

errors.add(toFieldValidatorError(violation));

}

return ResponseBean.validatorError(errors);

}

private FieldValidatorError toFieldValidatorError(ConstraintViolation> violation) {

Path.Node lastNode = null;

for (Path.Node node : violation.getPropertyPath()) {

lastNode = node;

}

FieldValidatorError fieldNotValidError = new FieldValidatorError();

// fieldNotValidError.setType(ValidatorTypeMapping.toType(violation.getConstraintDescriptor().getAnnotation().annotationType()));

fieldNotValidError.setType(ValidatorErrorType.INVALID.value());

fieldNotValidError.setField(lastNode.getName());

fieldNotValidError.setMessage(violation.getMessage());

return fieldNotValidError;

}

private FieldValidatorError toFieldValidatorError(FieldError error) {

FieldValidatorError fieldNotValidError = new FieldValidatorError();

fieldNotValidError.setType(ValidatorErrorType.INVALID.value());

fieldNotValidError.setField(error.getField());

fieldNotValidError.setMessage(error.getDefaultMessage());

return fieldNotValidError;

}

/**

* BindException: 数据绑定异常，效果与MethodArgumentNotValidException类似，为MethodArgumentNotValidException的父类

*/

@ExceptionHandler(BindException.class)

public ResponseBean handleBindException(HttpServletRequest request, BindException ex) {

logger.debug(ex);

return validatorErrors(ex.getBindingResult());

}

/**

* 返回值类型转化错误

*/

@ExceptionHandler(HttpMessageConversionException.class)

public ResponseBean exceptionHandle(HttpServletRequest request,

HttpMessageConversionException ex) {

return internalServiceError(ex);

}

/**

* 对应 Http 请求头的 accept

* 客户器端希望接受的类型和服务器端返回类型不一致。

* 这里虽然设置了拦截，但是并没有起到作用。需要通过http请求的流程来进一步确定原因。

*/

@ExceptionHandler(HttpMediaTypeNotAcceptableException.class)

public ResponseBean handleHttpMediaTypeNotAcceptableException(HttpServletRequest request,

HttpMediaTypeNotAcceptableException ex) {

logger.debug(ex);

StringBuilder messageBuilder = new StringBuilder().append("The media type is not acceptable.")

.append(" Acceptable media types are ");

ex.getSupportedMediaTypes().forEach(t -> messageBuilder.append(t + ", "));

String message = messageBuilder.substring(0, messageBuilder.length() - 2);

return new ResponseBean(HttpStatus.NOT_ACCEPTABLE.value(), message);

}

/**

* 对应请求头的 content-type

* 客户端发送的数据类型和服务器端希望接收到的数据不一致

*/

@ExceptionHandler(HttpMediaTypeNotSupportedException.class)

public ResponseBean handleHttpMediaTypeNotSupportedException(HttpServletRequest request,

HttpMediaTypeNotSupportedException ex) {

logger.debug(ex);

StringBuilder messageBuilder = new StringBuilder().append(ex.getContentType())

.append(" media type is not supported.").append(" Supported media types are ");

ex.getSupportedMediaTypes().forEach(t -> messageBuilder.append(t + ", "));

String message = messageBuilder.substring(0, messageBuilder.length() - 2);

System.out.println(message);

return new ResponseBean(HttpStatus.UNSUPPORTED_MEDIA_TYPE.value(), message);

}

/**

* 前端发送过来的数据无法被正常处理

* 比如后天希望收到的是一个json的数据，但是前端发送过来的却是xml格式的数据或者是一个错误的json格式数据

*/

@ExceptionHandler(HttpMessageNJDtYBBQKotReadableException.class)

public ResponseBean handlerHttpMessageNotReadableException(HttpServletRequest request,

HttpMessageNotReadableException ex) {

logger.debug(ex);

String message = "Problems parsing JSON";

return new ResponseBean(HttpStatus.BAD_REQUEST.value(), message);

}

/**

* 将返回的结果转化到响应的数据时候导致的问题。

* 当使用json作为结果格式时，可能导致的原因为序列化错误。

* 目前知道，如果返回一个没有属性的对象作为结果时，会导致该异常。

*/

@ExceptionHandler(HttpMessageNotWritableException.class)

public ResponseBean handlerHttpMessageNotWritableException(HttpServletRequest request,

HttpMessageNotWritableException ex) {

return internalServiceError(ex);

}

/**

* 请求方法不支持

*/

@ExceptionHandler(HttpRequestMethodNotSupportedException.class)

public ResponseBean exceptionHandle(HttpServletRequest request, HttpRequestMethodNotSupportedException ex) {

logger.debug(ex);

StringBuilder messageBuilder = new StringBuilder().append(ex.getMethod())

.append(" method is not supported for this request.").append(" Supported methods are ");

ex.getSupportedHttpMethods().forEach(m -> messageBuilder.append(m + ","));

String message = messageBuilder.substring(0, messageBuilder.length() - 2);

return new ResponseBean(HttpStatus.METHOD_NOT_ALLOWED.value(), message);

}

/**

* 参数类型不匹配

*/

@ExceptionHandler(MethodArgumentTypeMismatchException.class)

public ResponseBean methodArgumentTypeMismatchExceptionHandler(HttpServletRequest request,

MethodArgumentTypeMismatchException ex) {

logger.debug(ex);

String message = "The parameter '" + ex.getName() + "' should of type '"

+ ex.getRequiredType().getSimpleName().toLowerCase() + "'";

FieldValidatorError fieldNotValidError = new FJDtYBBQKieldValidatorError();

fieldNotValidError.setType(ValidatorErrorType.TYPE_MISMATCH.value());

fieldNotValidError.setField(ex.getName());

fieldNotValidError.setMessage(message);

return ResponseBean.validatorError(Arrays.asList(fieldNotValidError));

}

/**

* 缺少必填字段

*/

@ExceptionHandler(MissingServletRequestParameterException.class)

public ResponseBean exceptionHandle(HttpServletRequest request,

MissingServletRequestParameterException ex) {

logger.debug(ex);

String message = "Required parameter '" + ex.getParameterName() + "' is not present";

FieldValidatorError fieldNotValidError = new FieldValidatorError();

fieldNotValidError.setType(ValidatorErrorType.MISSING_FIELD.value());

fieldNotValidError.setField(ex.getParameterName());

fieldNotValidError.setMessage(message);

return ResponseBean.validatorError(Arrays.asList(fieldNotValidError));

}

/**

* 文件上传时，缺少　file 字段

*/

@ExceptionHandler(MissingServletRequestPartException.class)

public ResponseBean exceptionHandle(HttpServletRequest request, MissingServletRequestPartException ex) {

logger.debug(ex);

return new ResponseBean(HttpStatus.BAD_REQUEST.value(), ex.getMessage());

}

/**

* 请求路径不存在

*/

@ExceptionHandler(NoHandlerFoundException.class)

public ResponseBean exceptionHandle(HttpServletRequest request, NoHandlerFoundException ex) {

logger.debug(ex);

String message = "No resource found for " + ex.getHttpMethod() + " " + ex.getRequestURL();

return new ResponseBean(HttpStatus.NOT_FOUND.value(), message);

}

/**

* 缺少路径参数

* Controller方法中定义了　@PathVariable(required=true)　的参数，但是却没有在url中提供

*/

@ExceptionHandler(MissingPathVariableException.class)

public ResponseBean exceptionHandle(HttpServletRequest request, MissingPathVariableException ex) {

return internalServiceError(ex);

}

/**

* 其他所有的异常

*/

@ExceptionHandler()

public ResponseBean handleAll(HttpServletRequest request, Exception ex) {

return internalServiceError(ex);

}

private String codeToMessage(int code) {

//TODO 这个需要进行自定，每个 code 会匹配到一个相应的 msg

return "The code is " + code;

}

private ResponseBean internalServiceError(Exception ex) {

logException(ex);

// do something else

return ResponseBean.systemError();

}

private void logException(T e) {

logger.error(String.format(logExceptionFormat, e.getMessage()), e);

}

}

通过上面的配置，可以有效地将异常进行统一的处理，同时对返回的结果进行统一的封装。

总结

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