相信大部分后端開發(fā)人員在日常開發(fā)中都需要和前端對接，當然前后端都是你自己一個人搞的話可以想怎么玩就怎么玩，但是我們還是要做到一定的規(guī)范性。在前后端分離的項目中后端返回的格式一定要友好，并且固定，不能經(jīng)常變來變?nèi)?，不然會對前端的開發(fā)人員帶來很多的工作量。

SpringBoot Controller 常見的返回格式

String

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

postman調(diào)用結(jié)果：

自定義對象

正常返回

    @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調(diào)用結(jié)果：

錯誤返回

   @PostMapping("/error")
    public ActionResult error(){
        return ActionResult.defaultFail(1000,"服務(wù)器異常，請聯(lián)系管理員");
    }

postman調(diào)用結(jié)果：

定義返回對象

我定義兩個ActionResult這個對象來對返回值進行封裝，可以根據(jù)自己公司實際情況修改：

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

/**
 * @ClassName ActionResult
 * @Description 統(tǒng)一返回值封裝
 * @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;
    }
}

定義狀態(tài)枚舉

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"),
    /**
     * 未授權(quán)
     */
    RC401(401, "用戶未授權(quán)"),
    /**
     * 請求被禁止
     */
    RC403(403, "請求被禁止"),
    /**
     * 服務(wù)異常
     */
    RC500(500, "服務(wù)器異常，請聯(lián)系管理員"),
    /**
     * 操作失敗
     */
    RC999(999, "操作失敗"),

    RC1001(1001, "用戶名密碼錯誤"),
    RC1002(1002, "未授權(quán)的資源"),
    RC1003(1003, "未授權(quán)的資源"),
    RC1004(1004, "缺少請求參數(shù)異常"),
    RC1005(1005, "缺少請求體參數(shù)異常"),
    RC1006(1006, "參數(shù)綁定異常"),
    RC1007(1007, "方法參數(shù)無效異常");

    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;
    }
}

統(tǒng)一處理返回值及異常

實現(xiàn)原理：需要實現(xiàn)SpringBoot提供的ResponseBodyAdvice這個接口，完成統(tǒng)一返回值的封裝及異常的處理。實現(xiàn)了這個接口之后，在Controller返回的時候只需要將對象直接返回，有些不需要返回值的可以直接返回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: 全局異常處理以及返回值的統(tǒng)一封裝
 * @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;
    }

    /**
     * 統(tǒng)一包裝
     *
     * @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不需要再包一層（不想包一層ActionResult對象的可以在這里把這個對象過濾掉）
         */
        if (o instanceof String || o instanceof ActionResult) {
            return o;
        }
        return ActionResult.defaultOk(o);
    }

    /**
     * 系統(tǒng)內(nèi)部異常捕獲
     *
     * @param e
     * @return
     */
    @ResponseStatus(HttpStatus.INTERNAL_SERVER_ERROR)
    @ExceptionHandler(value = Exception.class)
    public Object exceptionHandler(Exception e) {
        log.error("系統(tǒng)內(nèi)部異常，異常信息", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC500);
    }
    /**
     * 忽略參數(shù)異常處理器;觸發(fā)例子:帶有@RequestParam注解的參數(shù)未給參數(shù)
     *
     * @param e 忽略參數(shù)異常
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(MissingServletRequestParameterException.class)
    public Object parameterMissingExceptionHandler(MissingServletRequestParameterException e) {
        log.error("缺少Servlet請求參數(shù)異常", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1004);
    }
    /**
     * 缺少請求體異常處理器;觸發(fā)例子:不給請求體參數(shù)
     *
     * @param e 缺少請求體異常
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(HttpMessageNotReadableException.class)
    public Object parameterBodyMissingExceptionHandler(HttpMessageNotReadableException e) {
        log.error("參數(shù)請求體異常", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1005);
    }


    /**
     * 統(tǒng)一處理請求參數(shù)綁定錯誤(實體對象傳參);
     *
     * @param e BindException
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler(BindException.class)
    public Object validExceptionHandler(BindException e) {
        log.error("方法參數(shù)綁定錯誤(實體對象傳參)", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1006);
    }
    /**
     * 統(tǒng)一處理請求參數(shù)綁定錯誤(實體對象請求體傳參);
     *
     * @param e 參數(shù)驗證異常
     * @return ResponseResult
     */
    @ResponseStatus(HttpStatus.BAD_REQUEST)
    @ExceptionHandler({MethodArgumentNotValidException.class})
    public Object parameterExceptionHandler(MethodArgumentNotValidException e) {
        log.error("方法參數(shù)無效異常(實體對象請求體傳參)", e);
        return ActionResult.defaultFail(ResultCodeEnum.RC1007);
    }
}