Spring MVC Controller返回值及異常的統(tǒng)一處理方法

更新時間：2019年11月02日 11:17:28 作者：donespeak

這篇文章主要給大家介紹了關(guān)于Spring MVC Controller返回值及異常的統(tǒng)一處理方法，文中通過示例代碼介紹的非常詳細(xì)，對大家的學(xué)習(xí)或者使用Spring MVC具有一定的參考學(xué)習(xí)價值，需要的朋友們下面來一起學(xué)習(xí)學(xué)習(xí)吧

舊的設(shè)計(jì)方案

開發(fā)api的時候,需要先定義好接口的數(shù)據(jù)響應(yīng)結(jié)果.如下是一個很簡單直接的Controller實(shí)現(xiàn)方法及響應(yīng)結(jié)果定義.

@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: {}, // 可以是對象或者數(shù)組
 msg: ""
}

從上面的代碼，我們可以看到對于每個 Controller 方法，都會有很多重復(fù)的代碼出現(xiàn)，我們應(yīng)該設(shè)法去避免重復(fù)的代碼。將重復(fù)的代碼移除之后，可以得到如下的代碼，簡單易懂。

@RestController
@RequestMapping("/users")
public class UserController {
  
 @Inject
 private UserService userService;

 @GetRequest("/{userId:\\d+}")
 public User signin(@PathVariable long userId) {
  return userService.getUserBaseInfo(userId);
 }
}

在以上的實(shí)現(xiàn)中，還做了一個必要的要求，就是 ServiceException 需要定義為 RuntimeException的子類，而不是 Exception的子類。由于 ServiceException 表示服務(wù)異常，一般發(fā)生這種異常是應(yīng)該直接提示前端，而無需進(jìn)行其他特殊處理的。在定義為 RuntimeException 的子類之后，會減少大量的異常拋出聲明，而且不再需要在事務(wù)@Transactional 中進(jìn)行特殊聲明。

統(tǒng)一 Controller 返回值格式

在開發(fā)的過程中，我發(fā)現(xiàn)上面的結(jié)構(gòu)

@ControllerAdvice
public class ControllerResponseHandler implements ResponseBodyAdvice<Object> {
 
 private Logger logger = LogManager.getLogger(getClass());

 @Override
 public boolean supports(MethodParameter returnType, Class<? extends HttpMessageConverter<?>> converterType) {
  // 支持所有的返回值類型
  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 {
   // 所有沒有返回　ResponseBean　結(jié)構(gòu)的結(jié)果均認(rèn)為是成功的
   return ResponseBean.success(body);
  }
 }
}

統(tǒng)一異常處理

如下的代碼中，ServiceException ServiceMessageException ValidatorErrorType FieldValidatorError 均為自定義類。

@ControllerAdvice
public class ControllerExceptionHandler {

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

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

 /**
  * 自定義異常
  */
 @ExceptionHandler(ServiceMessageException.class)
 public ResponseBean handleServiceMessageException(HttpServletRequest request, ServiceMessageException ex) {
  logger.debug(ex);
  return new ResponseBean(ex.getMsgCode(), ex.getMessage());
 }

 /**
  * 自定義異常
  */
 @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: 實(shí)體類屬性校驗(yàn)不通過
  * 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<FieldValidatorError> errors = new ArrayList<FieldValidatorError>();
  for (FieldError error : result.getFieldErrors()) {
   errors.add(toFieldValidatorError(error));
  }
  return ResponseBean.validatorError(errors);
 }

 /**
  * ConstraintViolationException: 直接對方法參數(shù)進(jìn)行校驗(yàn)，校驗(yàn)不通過。
  * 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<FieldValidatorError> errors = new ArrayList<FieldValidatorError>();

  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: 數(shù)據(jù)綁定異常，效果與MethodArgumentNotValidException類似，為MethodArgumentNotValidException的父類
  */
 @ExceptionHandler(BindException.class)
 public ResponseBean handleBindException(HttpServletRequest request, BindException ex) {
  logger.debug(ex);
  return validatorErrors(ex.getBindingResult());
 }

 /**
  * 返回值類型轉(zhuǎn)化錯誤
  */
 @ExceptionHandler(HttpMessageConversionException.class)
 public ResponseBean exceptionHandle(HttpServletRequest request,
   HttpMessageConversionException ex) {
  return internalServiceError(ex);
 }
 
 /**
  * 對應(yīng) Http 請求頭的 accept
  * 客戶器端希望接受的類型和服務(wù)器端返回類型不一致。
  * 這里雖然設(shè)置了攔截，但是并沒有起到作用。需要通過http請求的流程來進(jìn)一步確定原因。
  */
 @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);
 }

 /**
  * 對應(yīng)請求頭的 content-type
  * 客戶端發(fā)送的數(shù)據(jù)類型和服務(wù)器端希望接收到的數(shù)據(jù)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);
 }

 /**
  * 前端發(fā)送過來的數(shù)據(jù)無法被正常處理
  * 比如后天希望收到的是一個json的數(shù)據(jù)，但是前端發(fā)送過來的卻是xml格式的數(shù)據(jù)或者是一個錯誤的json格式數(shù)據(jù)
  */
 @ExceptionHandler(HttpMessageNotReadableException.class)
 public ResponseBean handlerHttpMessageNotReadableException(HttpServletRequest request,
   HttpMessageNotReadableException ex) {
  logger.debug(ex);
  String message = "Problems parsing JSON";
  return new ResponseBean(HttpStatus.BAD_REQUEST.value(), message);
 }

 /**
  * 將返回的結(jié)果轉(zhuǎn)化到響應(yīng)的數(shù)據(jù)時候?qū)е碌膯栴}。
  * 當(dāng)使用json作為結(jié)果格式時，可能導(dǎo)致的原因?yàn)樾蛄谢e誤。
  * 目前知道，如果返回一個沒有屬性的對象作為結(jié)果時，會導(dǎo)致該異常。
  */
 @ExceptionHandler(HttpMessageNotWritableException.class)
 public ResponseBean handlerHttpMessageNotWritableException(HttpServletRequest request,
   HttpMessageNotWritableException ex) {
  return internalServiceError(ex);
 }

 /**
  * 請求方法不支持
  */
 @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);
 }

 /**
  * 參數(shù)類型不匹配
  */
 @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 FieldValidatorError();
  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));
 }

 /**
  * 文件上傳時，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());
 }

 /**
  * 請求路徑不存在
  */
 @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);
 }

 /**
  * 缺少路徑參數(shù)
  * Controller方法中定義了　@PathVariable(required=true)　的參數(shù)，但是卻沒有在url中提供
  */
 @ExceptionHandler(MissingPathVariableException.class)
 public ResponseBean exceptionHandle(HttpServletRequest request, MissingPathVariableException ex) {
  return internalServiceError(ex);
 }

 /**
  * 其他所有的異常
  */
 @ExceptionHandler()
 public ResponseBean handleAll(HttpServletRequest request, Exception ex) {
  return internalServiceError(ex);
 }

 private String codeToMessage(int code) {
  //TODO 這個需要進(jìn)行自定，每個 code 會匹配到一個相應(yīng)的 msg
  return "The code is " + code;
 }

 private ResponseBean internalServiceError(Exception ex) {
  logException(ex);
  // do something else
  return ResponseBean.systemError();
 }

 private <T extends Throwable> void logException(T e) {
  logger.error(String.format(logExceptionFormat, e.getMessage()), e);
 }
}

通過上面的配置，可以有效地將異常進(jìn)行統(tǒng)一的處理，同時對返回的結(jié)果進(jìn)行統(tǒng)一的封裝。

總結(jié)

以上就是這篇文章的全部內(nèi)容了，希望本文的內(nèi)容對大家的學(xué)習(xí)或者工作具有一定的參考學(xué)習(xí)價值，謝謝大家對腳本之家的支持。

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