SpringBoot后端返回统一的标准格式数据

1.@RestControllerAdvice，RestController的增强类，可用于实现全局异常处理器
2.@ExceptionHandler,统一处理某一类异常，从而减少代码重复率和复杂度，比如要获取自定义异常可以@ExceptionHandler(BusinessException.class)
3.@ResponseStatus指定客户端收到的http状态码

// 1.定义返回对象
@Data
public class ResultData<t> {
  /** 结果状态 ,具体状态码参见ResultData.java*/
  private int status;
  private String message;
  private T data;
  private long timestamp ;

  public ResultData (){
    this.timestamp = System.currentTimeMillis();
  }

  public static <t> ResultData<t> success(T data) {
    ResultData<t> resultData = new ResultData<>();
    resultData.setStatus(ReturnCode.RC100.getCode());
    resultData.setMessage(ReturnCode.RC100.getMessage());
    resultData.setData(data);
    return resultData;
  }

  public static <t> ResultData<t> fail(int code, String message) {
    ResultData<t> resultData = new ResultData<>();
    resultData.setStatus(code);
    resultData.setMessage(message);
    return resultData;
  }

}

// 2.定义状态码
public enum ReturnCode {
    /**操作成功**/
    RC100(100,"操作成功"),
    /**操作失败**/
    RC999(999,"操作失败"),
    /**服务限流**/
    RC200(200,"服务开启限流保护,请稍后再试!"),
    /**服务降级**/
    RC201(201,"服务开启降级保护,请稍后再试!"),
    /**热点参数限流**/
    RC202(202,"热点参数限流,请稍后再试!"),
    /**系统规则不满足**/
    RC203(203,"系统规则不满足要求,请稍后再试!"),
    /**授权规则不通过**/
    RC204(204,"授权规则不通过,请稍后再试!"),
    /**access_denied**/
    RC403(403,"无访问权限,请联系管理员授予权限"),
    /**access_denied**/
    RC401(401,"匿名用户访问无权限资源时的异常"),
    /**服务异常**/
    RC500(500,"系统异常，请稍后重试"),

    INVALID_TOKEN(2001,"访问令牌不合法"),
    ACCESS_DENIED(2003,"没有权限访问该资源"),
    CLIENT_AUTHENTICATION_FAILED(1001,"客户端认证失败"),
    USERNAME_OR_PASSWORD_ERROR(1002,"用户名或密码错误"),
    UNSUPPORTED_GRANT_TYPE(1003, "不支持的认证模式");

    /**自定义状态码**/
    private final int code;
    /**自定义描述**/
    private final String message;

    ReturnCode(int code, String message){
        this.code = code;
        this.message = message;
    }

    public int getCode() {
        return code;
    }

    public String getMessage() {
        return message;
    }
}

// 3.借助SpringBoot提供的ResponseBodyAdvice: 拦截Controller方法的返回值，统一处理返回值/响应体， 进一步封装；
/**
 * 编写实现类，统一处理返回值
 * @author
 * @date 2021/7/28 10:10 上午
 */
@RestControllerAdvice
public class ResponseAdvice implements ResponseBodyAdvice<object> {
    @Autowired
    private ObjectMapper objectMapper;

    @Override
    public boolean supports(MethodParameter methodParameter, Class<!--? extends HttpMessageConverter<?-->> aClass) {
        return true;
    }

    @SneakyThrows
    @Override
    public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class<!--? extends HttpMessageConverter<?-->> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
        if(o instanceof String){
            return objectMapper.writeValueAsString(ResultData.success(o));
        }        
        return ResultData.success(o);
    }
}

// 4. 进一步优化，全局异常处理
@Slf4j
@RestControllerAdvice
public class RestExceptionHandler {
    /**
     * 默认全局异常处理。
     * @param e the e
     * @return ResultData
     */
    @ExceptionHandler(Exception.class)
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    public ResultData<string> exception(Exception e) {
        log.error("全局异常信息 ex={}", e.getMessage(), e);
        return ResultData.fail(ReturnCode.RC500.getCode(),e.getMessage());
    }

}
// 5. 全局异常接入返回标准格式实现
@SneakyThrows
@Override
public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class<!--? extends HttpMessageConverter<?-->> aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
  if(o instanceof String){
    return objectMapper.writeValueAsString(ResultData.success(o));
  }
  if(o instanceof ResultData){
    return o;
  }
  return ResultData.success(o);
}