在一个完整的项目中，如果每一个控制器的方法都返回不同的结果，那么对项目的维护和扩展都会很麻烦；并且现在主流的开发模式时前后端分离的模式，如果后端返回各式各样的结果，那么在前后端联调时会非常的麻烦，还会增加前后端的格外任务。
所以，在一个项目中统一返回结果就是一个十分必要和友好的做法。接下来就用一个简单的demo来看看统一返回结果的效果。

1.创建Spring Boot项目

这里比较简单，就不详细介绍了；将多余的文件删除，保持项目的整洁；引入必要的依赖。
demo的项目结构
在这里插入图片描述

        <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter</artifactId></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><optional>true</optional></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-jdbc</artifactId></dependency><dependency><groupId>org.mybatis.spring.boot</groupId><artifactId>mybatis-spring-boot-starter</artifactId><version>1.3.2</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-test</artifactId><scope>test</scope></dependency>

2.返回结果的封装

在common包下创建Result结果类，将需要返回的必要数据封装在Result结果类中；这里封装三个属性，第一个是返回的状态码，第二个是返回的描述信息，第三个是返回的数据，此数据是前端需要接收展示的数据。

Result.java

@Setter
@Getter
@ToString
public class Result<T> implements Serializable {private static final long serialVersionUID = 1L;private int resultCode;private String message;private T data;public Result(){}public Result(int resultCode, String message){this.resultCode = resultCode;this.message = message;}// 服务器处理失败public Result failure(){return new Result(Constants.RESULT_CODE_SERVER_ERROR, "服务器错误");}}

创建Constants类，规定基本的状态码所代表的含义；这些状态码的基本规定需要符合常见的状态码含义，并且在一个项目能够保证统一即可。
Constants.java

public class Constants {public static final int RESULT_CODE_SUCCESS = 200;  // 成功处理请求public static final int RESULT_CODE_BAD_REQUEST = 412;  // 请求错误public static final int RESULT_CODE_NOT_LOGIN = 402;  // 未登录public static final int RESULT_CODE_PARAM_ERROR = 406;  // 传参错误public static final int RESULT_CODE_SERVER_ERROR= 500;  // 服务器错误// 等等，可以根据场景继续添加
}

最后创建结果类生成器ResultGenerator类，用于生成结果类。
ResultGenerator.java

public class ResultGenerator {private static final String DEFAULT_SUCCESS_MESSAGE = "SUCCESS";private static final String DEFAULT_FAIL_MESSAGE = "FAIL";public static Result genSuccessResult(){Result result = new Result();result.setResultCode(Constants.RESULT_CODE_SUCCESS);result.setMessage(DEFAULT_FAIL_MESSAGE);return result;}public static Result genSuccessResult(String message){Result result = new Result();result.setResultCode(Constants.RESULT_CODE_SUCCESS);result.setMessage(message);return result;}public static Result genSuccessResult(Object data){Result result = new Result();result.setResultCode(Constants.RESULT_CODE_SUCCESS);result.setMessage(DEFAULT_SUCCESS_MESSAGE);result.setData(data);return result;}public static Result genFailResult(String message){Result result = new Result();result.setResultCode(Constants.RESULT_CODE_SERVER_ERROR);if(StringUtils.isEmpty(message)){result.setMessage(DEFAULT_FAIL_MESSAGE);}else{result.setMessage(message);}return result;}public static Result genNullResult(String message){Result result = new Result();result.setResultCode(Constants.RESULT_CODE_BAD_REQUEST);result.setMessage(message);return result;}public static Result genErrorResult(int code, String message){Result result = new Result();result.setResultCode(code);result.setMessage(message);return result;}
}

3.后端接口实现

这里实现简单的增删改查，并且应用统一返回结果。

3.1 创建实体类

User.java

@Setter
@Getter
@Generated
@ToString
public class User {private Integer id;private String name;private String password;
}

3.2 创建dao层

UserDao.java

public interface UserDao {/*** 查询所有的用户* @return*/public List<User> findAllUsers();/*** 根据主键查询用户* @param id* @return*/public User getUserById(Integer id);/*** 添加一个用户* @param user* @return*/public int insertUser(User user);/*** 修改一个用户信息* @param user* @return*/public int updateUser(User user);/*** 删除一个用户* @param id* @return*/public int deleteUser(Integer id);}

userDao.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.picacho.dao.UserDao"><resultMap type="com.picacho.entity.User" id="UserResult"><result property="id" column="id"/><result property="name" column="name"/><result property="password" column="password"/></resultMap><select id="findAllUsers" resultMap="UserResult">select id,name,password from tb_userorder by id desc</select><select id="getUserById" resultMap="UserResult">select id,name,password from tb_userwhere id = #{id}</select><insert id="insertUser" parameterType="com.picacho.entity.User">insert into tb_user(name,password)values(#{name},#{password})</insert><update id="updateUser" parameterType="com.picacho.entity.User">update tb_usersetname=#{name},password=#{password}where id=#{id}</update><delete id="deleteUser" parameterType="int">delete from tb_user where id=#{id}</delete></mapper>

3.3 创建Controller层

这里基本没有任何业务逻辑可言，只是单纯的增删改查，所以也就不太需要业务层了。
UserController.java

@Controller
public class UserController {@AutowiredUserDao userDao;/*** 查询所有用户* @return*/@RequestMapping(value = "/users", method = RequestMethod.GET)@ResponseBodypublic Result<List<User>> queryAll(){List<User> users = userDao.findAllUsers();return ResultGenerator.genSuccessResult(users);}/*** 查询一个用户* @param id* @return*/@RequestMapping(value = "/users/{id}", method = RequestMethod.GET)@ResponseBodypublic Result<User> queryOne(@PathVariable("id") Integer id){if(id == null || id < 1){return ResultGenerator.genFailResult("缺少参数");}User user = userDao.getUserById(id);if(user == null){return ResultGenerator.genFailResult("无此数据");}return  ResultGenerator.genSuccessResult(user);}/*** 添加一个用户* @param user* @return*/@RequestMapping(value = "/users", method = RequestMethod.POST)@ResponseBodypublic Result<Boolean> insert(@RequestBody User user){if(StringUtils.isEmpty(user.getName()) || StringUtils.isEmpty(user.getPassword())){return ResultGenerator.genFailResult("缺少参数");}return ResultGenerator.genSuccessResult(userDao.insertUser(user) > 0);}/*** 修改用户信息* @param user* @return*/@RequestMapping(value = "/users", method = RequestMethod.PUT)@ResponseBodypublic Result<Boolean> update(@RequestBody User user){if(user.getId() == null || user.getId() < 1 || StringUtils.isEmpty(user.getName()) || StringUtils.isEmpty(user.getPassword())){return ResultGenerator.genFailResult("缺少参数");}User tempUser = userDao.getUserById(user.getId());if(tempUser == null){return ResultGenerator.genFailResult("参数异常");}tempUser.setName(user.getName());tempUser.setPassword(user.getPassword());return ResultGenerator.genSuccessResult(userDao.updateUser(tempUser) > 0);}/*** 删除一个用户* @param id* @return*/@RequestMapping(value = "/users/{id}", method = RequestMethod.DELETE)@ResponseBodypublic Result<Boolean> delete(@PathVariable("id") Integer id){if(id == null || id < 1){return ResultGenerator.genFailResult("缺少参数");}return ResultGenerator.genSuccessResult(userDao.deleteUser(id) > 0);}}

4.前端部分

这里前端使用ajax来与后端进行交互，所以前端资源只需要引入jquery即可。

<script src="https://cdn.staticfile.org/jquery/1.12.0/jquery.min.js"></script>

user-test.html

<!DOCTYPE html>
<html>
<head><meta charset="utf-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><title>统一返回结果 ｜ 请求测试</title>
</head>
<body class="hold-transition login-page">
<div style="width:720px;margin:7% auto"><div class="content"><div class="container-fluid"><div class="row"><div class="col-lg-6"><hr><div class="card"><div class="card-header"><h5 class="m-0">详情查询接口测试</h5></div><div class="card-body"><input id="queryId" type="number" placeholder="请输入id字段"><h6 class="card-title">查询接口返回数据如下：</h6><p class="card-text" id="result0"></p><a href="#" class="btn btn-primary" onclick="requestQuery()">发送详情查询请求</a></div></div><br><hr><div class="card"><div class="card-header"><h5 class="m-0">列表查询接口测试</h5></div><div class="card-body"><h6 class="card-title">查询接口返回数据如下：</h6><p class="card-text" id="result1"></p><a href="#" class="btn btn-primary" onclick="requestQueryList()">发送列表查询请求</a></div></div><br><hr><div class="card"><div class="card-header"><h5 class="m-0">添加接口测试</h5></div><div class="card-body"><input id="addName" type="text" placeholder="请输入name字段"><input id="addPassword" type="text" placeholder="请输入password字段"><h6 class="card-title">添加接口返回数据如下：</h6><p class="card-text" id="result2"></p><a href="#" class="btn btn-primary" onclick="requestAdd()">发送添加请求</a></div></div><br><hr><div class="card"><div class="card-header"><h5 class="m-0">修改接口测试</h5></div><div class="card-body"><input id="updateId" type="number" placeholder="请输入id字段"><input id="updateName" type="text" placeholder="请输入name字段"><input id="updatePassword" type="text" placeholder="请输入password字段"><h6 class="card-title">修改接口返回数据如下：</h6><p class="card-text" id="result3"></p><a href="#" class="btn btn-primary" onclick="requestUpdate()">发送修改请求</a></div></div><br><hr><div class="card"><div class="card-header"><h5 class="m-0">删除接口测试</h5></div><div class="card-body"><input id="deleteId" type="number" placeholder="请输入id字段"><h6 class="card-title">删除接口返回数据如下：</h6><p class="card-text" id="result4"></p><a href="#" class="btn btn-primary" onclick="requestDelete()">发送删除请求</a></div></div><hr></div></div></div></div>
</div><!-- jQuery -->
<script src="https://cdn.staticfile.org/jquery/1.12.0/jquery.min.js"></script>
<script type="text/javascript">function requestQuery() {var id = $("#queryId").val();if (typeof id == "undefined" || id == null || id == "" || id < 0) {return false;}$.ajax({type: "GET",//方法类型dataType: "json",//预期服务器返回的数据类型url: "/users/" + id,contentType: "application/json; charset=utf-8",success: function (result) {$("#result0").html(JSON.stringify(result));},error: function () {$("#result0").html("接口异常，请联系管理员！");}});}function requestQueryList() {$.ajax({type: "GET",//方法类型dataType: "json",//预期服务器返回的数据类型url: "/users",contentType: "application/json; charset=utf-8",success: function (result) {$("#result1").html(JSON.stringify(result));},error: function () {$("#result1").html("接口异常，请联系管理员！");}});}function requestAdd() {var name = $("#addName").val();var password = $("#addPassword").val();var data = {"name": name, "password": password}$.ajax({type: "POST",//方法类型dataType: "json",//预期服务器返回的数据类型url: "/users",contentType: "application/json; charset=utf-8",data: JSON.stringify(data),success: function (result) {$("#result2").html(JSON.stringify(result));},error: function () {$("#result2").html("接口异常，请联系管理员！");}});}function requestUpdate() {var id = $("#updateId").val();var name = $("#updateName").val();var password = $("#updatePassword").val();var data = {"id": id, "name": name, "password": password}$.ajax({type: "PUT",//方法类型dataType: "json",//预期服务器返回的数据类型url: "/users",contentType: "application/json; charset=utf-8",data: JSON.stringify(data),success: function (result) {$("#result3").html(JSON.stringify(result));},error: function () {$("#result3").html("接口异常，请联系管理员！");}});}function requestDelete() {var id = $("#deleteId").val();if (typeof id == "undefined" || id == null || id == "" || id < 0) {return false;}$.ajax({type: "DELETE",//方法类型dataType: "json",//预期服务器返回的数据类型url: "/users/" + id,contentType: "application/json; charset=utf-8",success: function (result) {$("#result4").html(JSON.stringify(result));},error: function () {$("#result4").html("接口异常，请联系管理员！");}});}
</script>
</body>
</html>