How to handle SpringBoot unified return format

Background

I believe that most back-end developers need to interface with the front-end in daily development. Of course, if you do the front-end and back-end by yourself, you can play whatever you want, but we still have to Achieve certain standardization. In projects with front-end and back-end separation, the format returned by the back-end must be friendly and fixed, and cannot be changed frequently, otherwise it will bring a lot of workload to the front-end developers.

SpringBoot Controller common return format

String

@PostMapping("/test")
public String test(){
    return "Hello World";
}

postman call result:

Custom object

Normal return

    @PostMapping("/getUser")
    public ActionResult getUser(){
        User user = new User();
        user.setId(UUID.randomUUID().toString());
        user.setName("MrDong");
        user.setAge(20);
        return ActionResult.defaultOk(user);
    }

postman call result:

Error return

   @PostMapping("/error")
    public ActionResult error(){
        return ActionResult.defaultFail(1000,"服务器异常，请联系管理员");
    }

Postman call result:

Define the return object

I define two ActionResult objects to encapsulate the return value , which can be modified according to the actual situation of your company:

package com.wxd.entity;
import com.wxd.enums.ResultCodeEnum;
import lombok.Data;

/**
 * @ClassName ActionResult
 * @Description 统一返回值封装
 * @Author Mr Dong
 * @Date 2022/7/26 14:51
 */
@Data
public class ActionResult {
    private Integer code;
    private String msg;
    private Integer count;
    private Object data;
    public static ActionResult defaultOk(Integer code, String msg, Integer count, Object data) {
        return new ActionResult(code, msg, count, data);
    }

    public static ActionResult defaultOk(Integer count, Object data) {
        return new ActionResult(ResultCodeEnum.RC200, count, data);
    }

    public static ActionResult defaultOk(Object data) {
        return new ActionResult(ResultCodeEnum.RC200, null, data);
    }

    public static ActionResult defaultOk() {
        return new ActionResult(ResultCodeEnum.RC200);
    }
    public static ActionResult defaultFail() {
        return new ActionResult(ResultCodeEnum.RC999);
    }
    public static ActionResult defaultFail(Integer code, String msg) {
        return new ActionResult(code, msg);
    }
    public static ActionResult defaultFail(ResultCodeEnum resultCodeEnum) {
        return new ActionResult(resultCodeEnum);
    }
    public ActionResult(Integer code, String msg, Integer count, Object data) {
        this.code = code;
        this.msg = msg;
        this.count = count;
        this.data = data;
    }
    public ActionResult(Integer code, String msg) {
        this.code = code;
        this.msg = msg;
    }
    public ActionResult(ResultCodeEnum resultCodeEnum) {
        this.code = resultCodeEnum.getCode();
        this.msg = resultCodeEnum.getMessage();
    }
    public ActionResult(ResultCodeEnum resultCodeEnum, Integer count, Object data) {
        this.code = resultCodeEnum.getCode();
        this.msg = resultCodeEnum.getMessage();
        this.count = count;
        this.data = data;
    }
}

Define status enumeration

package com.wxd.enums;

/**
 * @author wxd
 * @version V1.0
 * @description ResultCodeEnum
 * @date 2022/8/10 13:35
 **/
public enum ResultCodeEnum {
    /**
     * 操作成功
     */
    RC200(200, "操作成功"),
    /**
     * 未授权
     */
    RC401(401, "用户未授权"),
    /**
     * 请求被禁止
     */
    RC403(403, "请求被禁止"),
    /**
     * 服务异常
     */
    RC500(500, "服务器异常，请联系管理员"),
    /**
     * 操作失败
     */
    RC999(999, "操作失败"),

    RC1001(1001, "用户名密码错误"),
    RC1002(1002, "未授权的资源"),
    RC1003(1003, "未授权的资源"),
    RC1004(1004, "缺少请求参数异常"),
    RC1005(1005, "缺少请求体参数异常"),
    RC1006(1006, "参数绑定异常"),
    RC1007(1007, "方法参数无效异常");

    private Integer code;
    private String message;

    ResultCodeEnum(Integer code, String message) {
        this.code = code;
        this.message = message;
    }

    public Integer getCode() {
        return code;
    }

    public String getMessage() {
        return message;
    }
}

Unified processing of return values ​​and exceptions

Implementation principle: You need to implement the ResponseBodyAdvice interface provided by SpringBoot , complete the encapsulation of unified return values ​​and exception handling. After implementing this interface, you only need to return the object directly when the Controller returns. Some that do not need a return value can directly return void.

package com.wxd.advice;

import com.wxd.entity.ActionResult;
import com.wxd.enums.ResultCodeEnum;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.MethodParameter;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.converter.HttpMessageNotReadableException;
import org.springframework.http.server.ServerHttpRequest;
import org.springframework.http.server.ServerHttpResponse;
import org.springframework.validation.BindException;
import org.springframework.web.bind.MethodArgumentNotValidException;
import org.springframework.web.bind.MissingServletRequestParameterException;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.ResponseStatus;
import org.springframework.web.bind.annotation.RestControllerAdvice;
import org.springframework.web.servlet.mvc.method.annotation.ResponseBodyAdvice;

/**
 * @version: V1.0
 * @author: wxd
 * @description: 全局异常处理以及返回值的统一封装
 * @Date 2022/7/26 16:24
 */
@RestControllerAdvice(value = "com.wxd.controller")
@Slf4j
public class ResponseAdvice implements ResponseBodyAdvice {

    @Override
    public boolean supports(MethodParameter methodParameter, Class aClass) {
        return true;
    }

    /**
     * 统一包装
     *
     * @param o
     * @param methodParameter
     * @param mediaType
     * @param aClass
     * @param serverHttpRequest
     * @param serverHttpResponse
     * @return
     */
    @Override
    public Object beforeBodyWrite(Object o, MethodParameter methodParameter, MediaType mediaType, Class aClass, ServerHttpRequest serverHttpRequest, ServerHttpResponse serverHttpResponse) {
        /**
         * String、ActionResult不需要再包一层（不想包一层ActionResult对象的可以在这里把这个对象过滤掉）
         */
        if (o instanceof String || o instanceof ActionResult) {
            return o;
        }
        return ActionResult.defaultOk(o);
    }

    /**
     * 系统内部异常捕获
     *
     * @param e
     * @return
     */
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    @ExceptionHandler(value = Exception.class)
    public Object exceptionHandler(Exception e) {
        log.error("系统内部异常，异常信息", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC500);
    }
    /**
     * 忽略参数异常处理器;触发例子:带有@RequestParam注解的参数未给参数
     *
     * @param e 忽略参数异常
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(MissingServletRequestParameterException.class)
    public Object parameterMissingExceptionHandler(MissingServletRequestParameterException e) {
        log.error("缺少Servlet请求参数异常", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1004);
    }
    /**
     * 缺少请求体异常处理器;触发例子:不给请求体参数
     *
     * @param e 缺少请求体异常
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(HttpMessageNotReadableException.class)
    public Object parameterBodyMissingExceptionHandler(HttpMessageNotReadableException e) {
        log.error("参数请求体异常", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1005);
    }


    /**
     * 统一处理请求参数绑定错误(实体对象传参);
     *
     * @param e BindException
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(BindException.class)
    public Object validExceptionHandler(BindException e) {
        log.error("方法参数绑定错误(实体对象传参)", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1006);
    }
    /**
     * 统一处理请求参数绑定错误(实体对象请求体传参);
     *
     * @param e 参数验证异常
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler({MethodArgumentNotValidException.class})
    public Object parameterExceptionHandler(MethodArgumentNotValidException e) {
        log.error("方法参数无效异常(实体对象请求体传参)", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1007);
    }
}

void No return value

Have return value

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