Java设计通用的返回数据格式过程讲解

public class ResultInfo<T> {
	//通用返回信息对象类
	private int code;   //返回状态码
	private String msg;	//返回信息
	private T data;     //返回数据
	public ResultInfo<T> setCode(int code){
		this.code = code;
		return this;
	}
	public int getCode(){		
		return this.code;
	}
	public ResultInfo<T> setMsg(String msg){
		this.msg = msg;
		return this;
	}
	public String getMsg(){		
		return this.msg;
	}
	public ResultInfo<T> setData(T data){
		this.data = data;
		return this;
	}
	public T getData(){		
		return this.data;
	}
	//more functon here...
}

public class Result {
	//通用返回结果的方法类
	private static final int okCode = 0;
	private static final int failCode = 1;
	private static final String okMsg = "操作成功";
	private static final String failMsg = "操作失败";
	//以上这些通常可以定义为一种枚举类，然后使用
	//成功返回方法
	public static <T> ResultInfo<T> Ok(){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(okCode).setMsg(okMsg);
		return r;
	}
	public static <T> ResultInfo<T> Ok(String msg){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(okCode).setMsg(msg);
		return r;
	}
	public static <T> ResultInfo<T> Ok(T data){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(okCode).setMsg(okMsg).setData(data);
		return r;
	}
	public static <T> ResultInfo<T> Ok(String msg, T data){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(okCode).setMsg(msg).setData(data);
		return r;
	}
	//失败返回方法
	public static <T> ResultInfo<T> Fail(){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(failCode).setMsg(failMsg);
		return r;
	}
	public static <T> ResultInfo<T> Fail(String msg){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(failCode).setMsg(msg);
		return r;
	}
	public static <T> ResultInfo<T> Fail(T data){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(failCode).setMsg(failMsg).setData(data);
		return r;
	}
	public static <T> ResultInfo<T> Fail(String msg, T data){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(failCode).setMsg(msg).setData(data);
		return r;
	}
	//通用返回方法
	public static <T> ResultInfo<T> result(int code, String msg){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(code).setMsg(msg);
		return r;
	}
	public static <T> ResultInfo<T> result(int code, String msg, T data){
		ResultInfo<T> r = new ResultInfo<T>();
		r.setCode(code).setMsg(msg).setData(data);
		return r;
	}
}

package com.xxx.yyy.zzz.controller;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import com.xxx.yyy.zzz.util.ResultInfo;
import com.xxx.yyy.zzz.util.Result;
import com.xxx.yyy.zzz.model.User;
import com.xxx.yyy.zzz.service.UserService;
import org.springframework.stereotype.Controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.ResquestBody;
// more import ...
/**
* 用户对外API
* @author shenzhenNBA
* @since 2020.03.05
* 通用返回结果的应用
*/
@RequestMapping("/user")
@Controller
public class UserController {
	private static Log Logger = LogFactory.getLog(UserController.class);
	@Autowired
	UserService userService; //需另外定义,此处省略
	/**
	* 保存用户,
	* 返回格式: {"code":xx,"msg":"yyy","data":null}
	*/
	@PostMapping(value="/save")
	@ResponseBody
	public ResultInfo<String> saveUser(@RequestBody User param){
		try{
			int num = userService.saveUser(param);
			if (0 == num) {
				return Ok("保存成功"); //通用方法Ok()使用
			} else if (1 == num) {
				return Fail("失败，参数异常");  //通用方法Fail()使用
			} else if (2 == num) {
				return Fail("失败，保持操作失败");
			} else {
				return Fail("失败，未知异常");
			}
		} catch (Exception e) {
			Logger.error("controller UserController.saveUser() error, param: {}, info: {}", param, e)
			return Fail("保存失败，过程出现异常");
		}		
	}
	/**
	* 根据记录ID获取用户记录信息,
	* 返回格式: {"code":xx,"msg":"yyy","data":User对象JSON格式字符串}
	*/
	@PostMapping(value="/getById")
	@ResponseBody
	public ResultInfo<User> getById(@RequestBody UserParam param){
		try{
			User user = userService.getById(param);
			return Ok("查询成功", user);  //通用方法Ok()使用
		} catch (Exception e) {
			Logger.error("controller UserController.getById() error, param: {}, info: {}", param, e)
			return Fail("查询失败，过程出现异常",null); //通用方法Fail()使用
		}
	}	
}