1. 统一使用ResponseEntity类 : 用于统一响应格式

• 使用org.springframework.http.ResponseEntity作为统一响应格式

• 示例：

  @GetMapping("/as/{id}")
  @Timed
  public ResponseEntity<A> getA(@PathVariable Long id) {
      log.debug("REST request to get A : {}", id);
      A a = aService.findOne(id);
      return ResponseUtil.wrapOrNotFound(Optional.ofNullable(a));
  }
  

2.统一的Error类 : 用于统一异常格式

• 统一使用org.zalando.problem.ThrowableProblem的子类作为异常格式

image.png

• 统一使用httpStatus作为错误编码

  public enum Status implements StatusType {
     CONTINUE(100, "Continue"),
     SWITCHING_PROTOCOLS(101, "Switching Protocols"),
     PROCESSING(102, "Processing"),
     CHECKPOINT(103, "Checkpoint"),
     OK(200, "OK"),
     CREATED(201, "Created"),
     ACCEPTED(202, "Accepted"),
     NON_AUTHORITATIVE_INFORMATION(203, "Non-Authoritative Information"),
     NO_CONTENT(204, "No Content"),
     RESET_CONTENT(205, "Reset Content"),
     PARTIAL_CONTENT(206, "Partial Content"),
     MULTI_STATUS(207, "Multi-Status"),
     ALREADY_REPORTED(208, "Already Reported"),
     IM_USED(226, "IM Used"),
     MULTIPLE_CHOICES(300, "Multiple Choices"),
     MOVED_PERMANENTLY(301, "Moved Permanently"),
     FOUND(302, "Found"),
     SEE_OTHER(303, "See Other"),
     NOT_MODIFIED(304, "Not Modified"),
     USE_PROXY(305, "Use Proxy"),
     TEMPORARY_REDIRECT(307, "Temporary Redirect"),
     PERMANENT_REDIRECT(308, "Permanent Redirect"),
     BAD_REQUEST(400, "Bad Request"),
     UNAUTHORIZED(401, "Unauthorized"),
     PAYMENT_REQUIRED(402, "Payment Required"),
     FORBIDDEN(403, "Forbidden"),
     NOT_FOUND(404, "Not Found"),
     METHOD_NOT_ALLOWED(405, "Method Not Allowed"),
     NOT_ACCEPTABLE(406, "Not Acceptable"),
     PROXY_AUTHENTICATION_REQUIRED(407, "Proxy Authentication Required"),
     REQUEST_TIMEOUT(408, "Request Timeout"),
     CONFLICT(409, "Conflict"),
     GONE(410, "Gone"),
     LENGTH_REQUIRED(411, "Length Required"),
     PRECONDITION_FAILED(412, "Precondition Failed"),
     REQUEST_ENTITY_TOO_LARGE(413, "Request Entity Too Large"),
     REQUEST_URI_TOO_LONG(414, "Request-URI Too Long"),
     UNSUPPORTED_MEDIA_TYPE(415, "Unsupported Media Type"),
     REQUESTED_RANGE_NOT_SATISFIABLE(416, "Requested Range Not Satisfiable"),
     EXPECTATION_FAILED(417, "Expectation Failed"),
     I_AM_A_TEAPOT(418, "I'm a teapot"),
     UNPROCESSABLE_ENTITY(422, "Unprocessable Entity"),
     LOCKED(423, "Locked"),
     FAILED_DEPENDENCY(424, "Failed Dependency"),
     UPGRADE_REQUIRED(426, "Upgrade Required"),
     PRECONDITION_REQUIRED(428, "Precondition Required"),
     TOO_MANY_REQUESTS(429, "Too Many Requests"),
     REQUEST_HEADER_FIELDS_TOO_LARGE(431, "Request Header Fields Too Large"),
     INTERNAL_SERVER_ERROR(500, "Internal Server Error"),
     NOT_IMPLEMENTED(501, "Not Implemented"),
     BAD_GATEWAY(502, "Bad Gateway"),
     SERVICE_UNAVAILABLE(503, "Service Unavailable"),
     GATEWAY_TIMEOUT(504, "Gateway Timeout"),
     HTTP_VERSION_NOT_SUPPORTED(505, "HTTP Version Not Supported"),
     VARIANT_ALSO_NEGOTIATES(506, "Variant Also Negotiates"),
     INSUFFICIENT_STORAGE(507, "Insufficient Storage"),
     LOOP_DETECTED(508, "Loop Detected"),
     BANDWIDTH_LIMIT_EXCEEDED(509, "Bandwidth Limit Exceeded"),
     NOT_EXTENDED(510, "Not Extended"),
     NETWORK_AUTHENTICATION_REQUIRED(511, "Network Authentication Required");
  
     private final int code;
     private final String reason;
  
     private Status(int statusCode, String reasonPhrase) {
         this.code = statusCode;
         this.reason = reasonPhrase;
     }
  
     public int getStatusCode() {
         return this.code;
    }
  
     public String getReasonPhrase() {
         return this.reason;
     }
   }
  

3.自定义异常 : 区分不同场景的异常

• 请求异常

  public class BadRequestAlertException extends AbstractThrowableProblem{
  
     private final String entityName;
  
     private final String errorKey;
  
     public BadRequestAlertException(String defaultMessage, String entityName, String errorKey) {
         this(ErrorConstants.DEFAULT_TYPE, defaultMessage, entityName, errorKey);
     }
  
     public BadRequestAlertException(URI type, String defaultMessage, String entityName, String errorKey) {
         super(type, defaultMessage, Status.BAD_REQUEST, null, null, null, getAlertParameters(entityName, errorKey));
         this.entityName = entityName;
         this.errorKey = errorKey;
     }
  
     public String getEntityName() {
         return entityName;
     }
  
     public String getErrorKey() {
         return errorKey;
     }
  
     private static Map<String, Object> getAlertParameters(String entityName, String errorKey) {
         Map<String, Object> parameters = new HashMap<>();
         parameters.put("message", "error." + errorKey);
         parameters.put("params", entityName);
         return parameters;
     }
  

  }

• 参数异常

  public class CustomParameterizedException extends AbstractThrowableProblem {
  
     private static final long serialVersionUID = 1L;
  
     private static final String PARAM = "param";
  
     public CustomParameterizedException(String message, String... params) {
         this(message, toParamMap(params));
     }
  
     public CustomParameterizedException(String message, Map<String, Object> paramMap) {
         super(ErrorConstants.PARAMETERIZED_TYPE, "Parameterized Exception", BAD_REQUEST, null, null, null, toProblemParameters(message, paramMap));
     }
  
     public static Map<String, Object> toParamMap(String... params) {
         Map<String, Object> paramMap = new HashMap<>();
         if (params != null && params.length > 0) {
             for (int i = 0; i < params.length; i++) {
                 paramMap.put(PARAM + i, params[i]);
             }
         }
         return paramMap;
     }
  
     public static Map<String, Object> toProblemParameters(String message, Map<String, Object> paramMap) {
         Map<String, Object> parameters = new HashMap<>();
         parameters.put("message", message);
         parameters.put("params", paramMap);
         return parameters;
     }
  

  }

• 并发异常
  org.springframework.dao.ConcurrencyFailureException

• 其他异常
  按需定义，继承org.zalando.problem.ThrowableProblem即可

4.实现ExceptionHandler : 用于拦截处理异常

@ControllerAdvice
public class ExceptionTranslator implements ProblemHandling {

  /**
   * Post-process Problem payload to add the message key for front-end if needed
   */
  @Override
  public ResponseEntity<Problem> process(@Nullable ResponseEntity<Problem> entity, NativeWebRequest request) {
      if (entity == null || entity.getBody() == null) {
          return entity;
      }
      Problem problem = entity.getBody();
      if (!(problem instanceof ConstraintViolationProblem || problem instanceof DefaultProblem)) {
          return entity;
      }
      ProblemBuilder builder = Problem.builder()
        .withType(Problem.DEFAULT_TYPE.equals(problem.getType()) ? ErrorConstants.DEFAULT_TYPE : problem.getType())
        .withStatus(problem.getStatus())
        .withTitle(problem.getTitle())
        .with("path",   request.getNativeRequest(HttpServletRequest.class).getRequestURI());

      if (problem instanceof ConstraintViolationProblem) {
          builder
            .with("violations", ((ConstraintViolationProblem) problem).getViolations())
            .with("message", ErrorConstants.ERR_VALIDATION);
        return new ResponseEntity<>(builder.build(), entity.getHeaders(), entity.getStatusCode());
      } else {
          builder
            .withCause(((DefaultProblem) problem).getCause())
            .withDetail(problem.getDetail())
            .withInstance(problem.getInstance());
        problem.getParameters().forEach(builder::with);
        if (!problem.getParameters().containsKey("message") && problem.getStatus() != null) {
            builder.with("message", "error.http." + problem.getStatus().getStatusCode());
        }
        return new ResponseEntity<>(builder.build(), entity.getHeaders(), entity.getStatusCode());
    }
}

  @Override
  public ResponseEntity<Problem> handleMethodArgumentNotValid(MethodArgumentNotValidException ex, @Nonnull NativeWebRequest request) {
      BindingResult result = ex.getBindingResult();
      List<FieldErrorVM> fieldErrors = result.getFieldErrors().stream()
        .map(f -> new FieldErrorVM(f.getObjectName(), f.getField(), f.getCode()))
        .collect(Collectors.toList());

      Problem problem = Problem.builder()
        .withType(ErrorConstants.CONSTRAINT_VIOLATION_TYPE)
        .withTitle("Method argument not valid")
        .withStatus(defaultConstraintViolationStatus())
        .with("message", ErrorConstants.ERR_VALIDATION)
        .with("fieldErrors", fieldErrors)
        .build();
      return create(ex, problem, request);
  }

  @ExceptionHandler(BadRequestAlertException.class)
  public ResponseEntity<Problem> handleBadRequestAlertException(BadRequestAlertException ex, NativeWebRequest request) {
      return create(ex, request, HeaderUtil.createFailureAlert(ex.getEntityName(), ex.getErrorKey(), ex.getMessage()));
  }

  @ExceptionHandler(ConcurrencyFailureException.class)
  public ResponseEntity<Problem> handleConcurrencyFailure(ConcurrencyFailureException ex, NativeWebRequest request) {
      Problem problem = Problem.builder()
        .withStatus(Status.CONFLICT)
        .with("message", ErrorConstants.ERR_CONCURRENCY_FAILURE)
        .build();
      return create(ex, problem, request);
  }
}

5.统一业务异常抛出

异常统一在service或者controller里面抛出，抛出异常类型为BadRequestAlertException

• 例子

@PostMapping("/as")
@Timed
public ResponseEntity<A> createA(@Valid @RequestBody A a) throws URISyntaxException {
    log.debug("REST request to save A : {}", a);
    if (a.getId() != null) {
        throw new BadRequestAlertException("A new a cannot already have an ID", ENTITY_NAME, "idexists");
    }
    A result = aService.save(a);
    return ResponseEntity.created(new URI("/api/as/" + result.getId()))
        .headers(HeaderUtil.createEntityCreationAlert(ENTITY_NAME, result.getId().toString()))
        .body(result);
}