在前后端分离的情况下，我们经常会定义一个统一的反回数据格式，通常都会包含状态码，返回信息，返回的数据，是否成功等参数。

1、ResultCode

  单独定义了一个ReturnCode枚举类用于存储代码和返回的Message

public enum ResultCode {
    //成功
    SUCCESS(200),
    // 失败
    FAIL(400),

    // 未认证（签名错误）
    UNAUTHORIZED(401),

    // 接口不存在
    NOT_FOUND(404),

    // 服务器内部错误
    INTERNAL_SERVER_ERROR(500);
    public int code;
    ResultCode(int code)
    {
        this.code=code;
    }
}

2、ResponseResult

/*
 统一返回信息
 */
public class ResponseResult<T> {
    public int code; //返回状态码200成功

    private String msg; //返回描述信息

    private T data; //返回内容体

    public ResponseResult<T> setCode(ResultCode retCode) {
        this.code = retCode.code;
        return this;
    }

    public int getCode() {
        return code;
    }

    public ResponseResult<T> setCode(int code) {
        this.code = code;
        return this;
    }

    public String getMsg() {
        return msg;
    }

    public ResponseResult<T> setMsg(String msg) {
        this.msg = msg;
        return this;
    }

    public T getData() {
        return data;
    }

    public ResponseResult<T> setData(T data) {
        this.data = data;
        return this;
    }

}

在定义一个统一返回类：

3、Response

public class Response {
    private final static String SUCCESS = "success";

    private final static String FAIL = "fail";

    public static <T> ResponseResult<T> makeOKRsp() {
        return new ResponseResult<T>().setCode(ResultCode.SUCCESS).setMsg(SUCCESS);
    }

    public static <T> ResponseResult<T> makeOKRsp(String message) {
        return new ResponseResult<T>().setCode(ResultCode.SUCCESS).setMsg(message);
    }

    public static <T> ResponseResult<T> makeOKRsp(T data) {
        return new ResponseResult<T>().setCode(ResultCode.SUCCESS).setMsg(SUCCESS).setData(data);
    }

    public static <T> ResponseResult<T> makeErrRsp(String message) {
        return new ResponseResult<T>().setCode(ResultCode.INTERNAL_SERVER_ERROR).setMsg(message);
    }

    public static <T> ResponseResult<T> makeRsp(int code, String msg) {
        return new ResponseResult<T>().setCode(code).setMsg(msg);
    }

    public static <T> ResponseResult<T> makeRsp(int code, String msg, T data) {
        return new ResponseResult<T>().setCode(code).setMsg(msg).setData(data);
    }
}

4、新建 IUserService

新建测试用户接口类

package com.example.demo.service;
import com.example.demo.entity.User;
public interface IUserService {
    public User getUserInfo();
}

5、新建 UserServiceImpl

新建测试用户信息服务类

package com.example.demo.service.impl;
import com.example.demo.entity.User;
import com.example.demo.service.UserService;
import org.springframework.stereotype.Service;

import java.io.File;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.logging.SimpleFormatter;

@Service
public class UserServiceImpl implements IUserService {
    public User getUserInfo(){
        User user = new User();
        user.setName("jack");
        user.setPassword(12341234);

        return user;
    }

}

6、在controller调用

 @Autowired
    UserService service;
    @RequestMapping(value = "/getUserItem",method = RequestMethod.GET)
    public ResponseResult<User> getUserItem(){
        try {
            User user = service.getUserInfo();
            String[] arr= new String[]{"测试"};
            return  Response.makeOKRsp(user);
        }catch (Exception e)
        {
            return  Response.makeErrRsp("查询用户信息异常");
        }
    }

返回结果：

7、全局异常处理器 

/**
 * 全局异常处理
 */
@RestControllerAdvice
public class GlobalExceptionHandler {

    /*============= 请求错误 start ==============================================*/

    /**
     * HTTP 请求方式不支持异常
     * HttpRequestMethodNotSupportedException
     * @return {@link ResponseResult}
     */
    @ExceptionHandler(value = HttpRequestMethodNotSupportedException.class)
    public ResponseResult httpRequestMethodNotSupportException(HttpRequestMethodNotSupportedException e, HttpServletRequest request) {
        return Response.makeErrRsp("请求方式不支持异常");
    }

    /*============= 请求错误 end ==============================================*/

}

 修改一下getUserItem让其抛出自定义查询返回null的异常：