详解如何在SpringBoot项目中使用统一返回结果

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

        <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_user
        order by id desc
    </select>

    <select id="getUserById" resultMap="UserResult">
        select id,name,password from tb_user
        where 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_user
        set
            name=#{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 {

    @Autowired
    UserDao userDao;


    /**
     * 查询所有用户
     * @return
     */
    @RequestMapping(value = "/users", method = RequestMethod.GET)
    @ResponseBody
    public 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)
    @ResponseBody
    public 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)
    @ResponseBody
    public 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)
    @ResponseBody
    public 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)
    @ResponseBody
    public 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>