Spring注解@RestControllerAdvice原理解析

Spring注解@RestControllerAdvice原理解析

这篇文章主要介绍了Spring注解@RestControllerAdvice原理解析,文中通过示例代码介绍的非常详细，对大家的学习或者工作具有一定的参考学习价值,需要的朋友可以参考下

前言

前段时间部门搭建新系统，需要出异常后统一接口的返回格式，于是用到了Spring的注解@RestControllerAdvice。现在把此注解的用法总结一下。

用法

首先定义返回对象ResponseDto

package com.staff.points.common;

import lombok.Data;

import java.io.Serializable;

@Data

public class ResponseDto implements Serializable {

private static final long serialVersionUID = -284719732991678911L;

private String code;

private String message;

private T data;

public static ResponseDto assemblingSuccessResponse(T data) {

ResponseDto responseDto = new ResponseDto<>();

responseDto.setCode(ResponseCodeEnum.SUCCESS.getCode());

responseDto.setMessage(ResponseCodeEnum.SUCCESS.getMessage());

responseDto.setData(data);

return responseDto;

}

public static ResponseDto assemblingSuccessResponse() {

ResponseDto responseDto = new ResponseDto<>();

responseDto.setCode(ResponseCodeEnum.SUCCESS.getCode());

responseDto.setMessage(ResponseCodeEnum.SUCCESS.getMessage());

responseDto.setData(null);

return responseDto;

}

public static ResponseDto assemblingFailureResponse(ResponseCodeEnum data) {

ResponseDto responseDto = new ResponseDto<>();

responseDto.setCode(data.FAILURE.getCode());

responseDto.setMessage(data.FAILURE.getMessage());

return responseDto;

}

public static ResponseDto assemblingFailureResponse() {

ResponseDto responseDto = new ResponseDto<>();

responseDto.setCode(ResponseCodeEnum.FAILURE.getCode());

responseDto.setMessage(ResponseCodeEnum.FAILURE.getMessage());

return responseDto;

}

}

然后定义返回码的枚举类，此处只定义了两种，有需要可以往下添加很多。

package com.staff.points.common;

import lombok.AllArgsConstructor;

import lombok.Getter;

@AllArgsConstructor

@Getter

public enum ResponseCodeEnum {

SUCCESS("00", "成功"),

FAILURE("01", "系统异常");

private String code;

private String message;

}

下面是自定义的异常类

package com.staff.points.common;

import lombok.Data;

@Data

public class StaffPointsException extends RuntimeException{

private String code;

private String message;

public StaffPointsException () {}

public StaffPointsException (Exception e) {

super(e);

}

public StaffPointsException (String code, String message) {

super(message);

this.code = code;

this.message = message;

}

public StaffPointsException (ResponseCodeEnum codeEnum) {

super(codeEnum.getMessage());

this.code = codeEnum.getCode();

this.message = codeEnum.getMessage();

}

}

然后是关键的@RestControllerAdvice修饰的类

package com.staff.points.exception;

import com.staff.points.common.ResponseCodeEnum;

import com.staff.points.common.ResponseDto;

import com.staff.points.common.StaffPointsException;

import org.slf4j.Logger;

import org.slf4j.LoggerFactory;

import org.springframework.stereotype.Component;

import org.springframework.web.bind.annotation.ExceptionHandler;

import org.springframework.web.bind.annotation.RestControllerAdvice;

@RestControllerAdvice

@Component

public class UnifyExceptionHandler {

private Logger logger = LoggerFactory.getLogger(UnifyExceptionHandler.class);

@ExceptionHandler(Exception.class)

public ResponseDto handlerCommonException (Exception e) {

ResponseDto responseDto = new ResponseDto<>();

responseDto.setCode(ResponseCodeEnum.FAILURE.getCode());

responseDto.setMessage(ResponseCodeEnum.FAILURE.getMessage());

logger.info("UnifyExceptionHandler.handlerCommonException exception:" + e);

return responseDto;

}

// 报StaffPointException时，对其进行拦截并处理的方法

@ExceptionHandler(StaffPointsException.class)

public ResponseDto handlerCustomizeException (StaffPointsException e) {

ResponseDto responseDto = new ResponseDto<>();

responseDto.setCode(e.getCode());

responseDto.setMessage(e.getMessage());

logger.info("UnifyExceptionHandler.handlerCustomizeException StaffPointsException:" + e);

return responseDto;

}

}

运行代码时，如果出现了StaffPointException，那么就会被拦截进入第27行的方法（就是说可以自由的在业务代码里往外throw自定义异常了）；如果出现了其他的异常，则进入18行的方法，统一返回。

验证一下，在代码里造一个NPE异常时，返回结果：

{

"code": "01",

"message": "系统异常",

"data": null

}

造一个StaffPointsException异常时，返回结果：

{

"code": "99",

"message": "自定义业务异常",

"data": null

}

它的作用原理，大体是先在spring初始化时将类扫描进容器，出异常后，在DispatcherServlet类的doDispatch方法中调用了对异常的拦截处理。

小结

看@RestControllerAdvice源码可以知道，它就是@ControllerAdvice和@ResponseBody的合并。此注解通过对异常的拦截实现的统一异常返回处理，如果大家在项目中有类似的需求，不妨试一下，好用又方便。

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