java统一结果返回（链式编程结果）

一、统一返回数据格式

项目中我们会将响应封装成json返回，一般我们会将所有接口的数据格式统一， 使前端(iOS Android, Web)对数据的操作更一致、轻松。

一般情况下，统一返回数据格式没有固定的格式，只要能描述清楚返回的数据状态以及要返回的具体数据就可以。但是一般会包含状态码、返回消息、数据这几部分内容

例如，我们的系统要求返回的基本数据格式如下：

1.列表数据格式：

{
  "success": true,
  "code": 20000,
  "message": "成功",
  "data": {
    "items": [
      {
        "id": "1",
        "name": "路飞",
        "intro": "海贼王路飞"
      }
    ]
  }
}

2.分页数据格式：

{
  "success": true,
  "code": 20000,
  "message": "成功",
  "data": {
    "total": 17,
    "rows": [
      {
        "id": "1",
        "name": "鸣人",
        "intro": "火影七代"
      }
    ]
  }
}

3.没有返回数据：

{
  "success": true,
  "code": 20000,
  "message": "成功",
  "data": {}
}

4.失败：

{
  "success": false,
  "code": 20001,
  "message": "失败",
  "data": {}
}

5.统一结果：

{
  "success": 布尔, //响应是否成功
  "code": 数字, //响应码
  "message": 字符串, //返回消息
  "data": HashMap //返回数据，放在键值对中
}

二、创建统一结果返回类

1.创建常量状态code

package com.stu.commonutils;

public interface ResultCode {
    public static Integer SUCCESS = 20000;

    public static Integer ERROR = 20001;
}

2.创建统一的返回结果类（基于lombok没有get和set方法）

package com.stu.commonutils;

import io.swagger.annotations.ApiModelProperty;
import lombok.Data;

import java.util.HashMap;
import java.util.Map;

@Data
public class ResultData {
    @ApiModelProperty(value = "是否成功")
    private Boolean success;

    @ApiModelProperty(value = "返回码")
    private Integer code;

    @ApiModelProperty(value = "返回消息")
    private String message;

    @ApiModelProperty(value = "返回数据")
    private Map<String, Object> data = new HashMap<String, Object>();


    private ResultData(){}

    public static ResultData success(){
        ResultData r = new ResultData();
        r.setSuccess(true);
        r.setCode(ResultCode.SUCCESS);
        r.setMessage("成功");
        return r;
    }

    public static ResultData error(){
        ResultData r = new ResultData();
        r.setSuccess(false);
        r.setCode(ResultCode.ERROR);
        r.setMessage("失败");
        return r;
    }
    public ResultData success(Boolean success){
        this.setSuccess(success);
        return this;
    }

    public ResultData message(String message){
        this.setMessage(message);
        return this;
    }

    public ResultData code(Integer code){
        this.setCode(code);
        return this;
    }

    public ResultData data(String key, Object value){
        this.data.put(key, value);
        return this;
    }

    public ResultData data(Map<String, Object> map){
        this.setData(map);
        return this;
    }

}

3.例子

package com.stu.eduservice.controller;


import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.stu.commonutils.ResultData;
import com.stu.eduservice.entity.EduCourse;
import com.stu.eduservice.entity.EduVideo;
import com.stu.eduservice.entity.vo.CoursePublishVo;
import com.stu.eduservice.entity.vo.CourseQuery;
import com.stu.eduservice.entity.vo.CourseVo;
import com.stu.eduservice.service.IEduCourseService;
import org.apache.commons.lang3.StringUtils;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * <p>
 * 课程 前端控制器
 * </p>
 *
 * @author stu
 * @since 2021-05-29
 */
@RestController
@RequestMapping("/eduservice/course")
@CrossOrigin
public class EduCourseController {

    @Autowired
    private IEduCourseService eduCourseService;

    //条件查询，分页
    @PostMapping("pageCourseCondition/{current}/{limit}")
    public ResultData pageTeacherCondition(@PathVariable long current,
                                           @PathVariable long limit,
                                           @RequestBody(required = false) CourseQuery courseQuery ){

        QueryWrapper wrapper = new QueryWrapper();

        String title = courseQuery.getTitle();
        String status = courseQuery.getStatus();


        if (!StringUtils.isEmpty(title)) {
            wrapper.like("title", title);
        }

        if (!StringUtils.isEmpty(status) ) {
            wrapper.eq("status", status);
        }

        Page<EduCourse> page = new Page<EduCourse>(current,limit);

        eduCourseService.page(page,wrapper);

        Map<String,Object> map = new HashMap<String,Object>();
        long total = page.getTotal();
        List<EduCourse> list = page.getRecords();
        map.put("total",total);
        map.put("list",list);
        return ResultData.success().data(map);//链式编程

    }
}