SpringBoot+MySQL+MyBatis（Mapper.xml方式）实现简单的多表CRUD（RESTful风格HTTP接口）

一、准备工作

1.1 创建Spring工程

在IntelliJ IDEA中新建Spring工程，选择Web、MyBatis、MySQL等依赖。
配置文件application.properties

spring.datasource.url=jdbc:mysql://localhost:3306/springbootdb?useUnicode=true&characterEncoding=utf8
spring.datasource.username=root
spring.datasource.password=123
spring.datasource.driver-class-name=com.mysql.jdbc.Driver

mybatis.mapper-locations=classpath:mapper/*xml

server.port=8084
server.servlet.context-path=/singlecandy

1.2 创建数据库和表

在SQLyog中，执行以下SQL语句，创建DataBase和Table：

/*
SQLyog Ultimate v12.08 (64 bit)
MySQL - 5.5.56 : Database - springbootdb
*********************************************************************
*/


/*!40101 SET NAMES utf8 */;

/*!40101 SET SQL_MODE=''*/;

/*!40014 SET @OLD_UNIQUE_CHECKS=@@UNIQUE_CHECKS, UNIQUE_CHECKS=0 */;
/*!40014 SET @OLD_FOREIGN_KEY_CHECKS=@@FOREIGN_KEY_CHECKS, FOREIGN_KEY_CHECKS=0 */;
/*!40101 SET @OLD_SQL_MODE=@@SQL_MODE, SQL_MODE='NO_AUTO_VALUE_ON_ZERO' */;
/*!40111 SET @OLD_SQL_NOTES=@@SQL_NOTES, SQL_NOTES=0 */;
CREATE DATABASE /*!32312 IF NOT EXISTS*/`springbootdb` /*!40100 DEFAULT CHARACTER SET utf8 */;

USE `springbootdb`;

/*Table structure for table `address` */

DROP TABLE IF EXISTS `address`;

CREATE TABLE `address` (
  `aid` int(11) NOT NULL,
  `city` varchar(16) DEFAULT NULL,
  PRIMARY KEY (`aid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

/*Data for the table `address` */

insert  into `address`(`aid`,`city`) values (1,'北京'),(2,'上海'),(3,'广州'),(4,'深圳'),(5,'杭州');

/*Table structure for table `company` */

DROP TABLE IF EXISTS `company`;

CREATE TABLE `company` (
  `cid` int(11) NOT NULL,
  `cname` varchar(16) DEFAULT NULL,
  `address_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`cid`),
  KEY `address_id` (`address_id`),
  CONSTRAINT `company_ibfk_1` FOREIGN KEY (`address_id`) REFERENCES `address` (`aid`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

/*Data for the table `company` */

insert  into `company`(`cid`,`cname`,`address_id`) values (0,'admin',4),(1,'阿里巴巴',5),(2,'腾讯',4),(3,'百度',1),(4,'京东',1),(5,'华为',4),(6,'网易',3),(7,'斗鱼',NULL),(8,'大疆',4);

/*Table structure for table `user` */

DROP TABLE IF EXISTS `user`;

CREATE TABLE `user` (
  `uid` int(11) NOT NULL,
  `username` varchar(16) DEFAULT NULL,
  `password` varchar(16) DEFAULT NULL,
  `company_id` int(11) DEFAULT NULL,
  PRIMARY KEY (`uid`),
  KEY `company_id` (`company_id`),
  CONSTRAINT `user_ibfk_1` FOREIGN KEY (`company_id`) REFERENCES `company` (`cid`) ON DELETE CASCADE ON UPDATE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

/*Data for the table `user` */

insert  into `user`(`uid`,`username`,`password`,`company_id`) values (0,'admin','123',0),(1,'马云','123',1),(2,'马化腾','123',2),(3,'李彦宏','123',3),(4,'刘强东','123',4),(5,'任正非','123',5),(6,'丁磊','123',6),(7,'张小龙','123',2),(8,'张三','123',8),(9,'李四',NULL,NULL);

/*!40101 SET SQL_MODE=@OLD_SQL_MODE */;
/*!40014 SET FOREIGN_KEY_CHECKS=@OLD_FOREIGN_KEY_CHECKS */;
/*!40014 SET UNIQUE_CHECKS=@OLD_UNIQUE_CHECKS */;
/*!40111 SET SQL_NOTES=@OLD_SQL_NOTES */;

表结构和表关系如下图：

二、代码编写

2.1 实体类

User.java

package com.jake.singlecandy.pojo;

import lombok.Data;

@Data
public class User {

    private Integer uid;

    private String username;

    private String password;

}

UserInfo.java

package com.jake.singlecandy.pojo;

import lombok.Data;

import java.util.List;

@Data
public class UserInfo {

    private List<User> users;

    private String cname;

    private String city;

}

2.2 持久层

UserDao.java

package com.jake.singlecandy.dao;

import com.jake.singlecandy.pojo.User;
import com.jake.singlecandy.pojo.UserInfo;
import org.apache.ibatis.annotations.Param;

import java.util.List;

public interface UserDao {

    List<User> findAllUsers();

    List<User> findAllUserInfo();

    User findUserById(Integer uid);

    UserInfo findUserInfoById(Integer uid);

    List<UserInfo> findUserInfoByUsernameAndCname(@Param("username") String username, @Param("cname") String cname);

    User findUserByName(@Param("username") String username);

    void insertUser(User user);

    void updateUser(User user);

    void deleteUserById(Integer uid);
    
}

映射文件：UserMapper.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.jake.singlecandy.dao.UserDao">
    <resultMap id="UserBaseResultMap" type="com.jake.singlecandy.pojo.User">
        <id property="uid" column="uid"></id>
        <result property="username" column="username"></result>
        <result property="password" column="password"></result>
    </resultMap>

    <resultMap id="UserInfoBaseResultMap" type="com.jake.singlecandy.pojo.UserInfo">
        <result property="city" column="city"></result>
        <result property="cname" column="cname"></result>
        <collection property="users" resultMap="UserBaseResultMap"></collection>
    </resultMap>

    <parameterMap id="User" type="com.jake.singlecandy.pojo.User"></parameterMap>

    <select id="findAllUsers" resultMap="UserBaseResultMap">
        select *
        from user
    </select>

    <select id="findAllUserInfo" resultMap="UserInfoBaseResultMap">
        SELECT *
        FROM
            USER AS u
            LEFT JOIN company AS c
                ON u.`company_id` = c.`cid`
            LEFT JOIN address AS a
                ON c.`address_id` = a.`aid`
    </select>

    <select id="findUserById" parameterType="Integer" resultMap="UserBaseResultMap">
        SELECT *
        FROM
            USER
        WHERE uid = #{uid}
    </select>

    <select id="findUserInfoById" parameterType="Integer" resultMap="UserInfoBaseResultMap">
        SELECT *
        FROM
            USER AS u
            LEFT JOIN company AS c
                ON u.`company_id` = c.`cid`
            LEFT JOIN address AS a
                ON c.`address_id` = a.`aid`
        WHERE u.`uid` = #{uid}
    </select>

    <select id="findUserInfoByUsernameAndCname" resultMap="UserInfoBaseResultMap">
        SELECT
        *
        FROM
        USER AS u
        LEFT JOIN company AS c
        ON u.`company_id` = c.`cid`
        LEFT JOIN address AS a
        ON c.`address_id` = a.`aid`
        <where>
            <if test="username != null">
                u.username = #{username}
            </if>
            <if test="cname != null">
                AND c.cname = #{cname}
            </if>
        </where>
    </select>

    <select id="findUserByName" resultMap="UserBaseResultMap">
        SELECT uid, username, password
        FROM
            user
        WHERE username = #{username}
    </select>

    <insert id="insertUser" parameterMap="User" useGeneratedKeys="true" keyProperty="id">
        insert into
            user (uid, username)
        values
            (#{uid}, #{username})
    </insert>

    <update id="updateUser" parameterMap="User">
        update
            user
        set
            username = #{username}
        where
            uid = #{uid}
    </update>

    <delete id="deleteUserById" parameterType="Integer">
        delete from
            user
        where
            uid = #{uid}
    </delete>

</mapper>

2.3 业务层

接口定义方法 UserService.java

package com.jake.singlecandy.service;

import com.jake.singlecandy.pojo.User;
import com.jake.singlecandy.pojo.UserInfo;

import java.util.List;

public interface UserService {

    List<User> findAllUsers();

    List<User> findAllUserInfo();

    User findUserById(Integer uid);

    UserInfo findUserInfoById(Integer uid);

    List<UserInfo> findUserInfoByUsernameAndCname(String username, String cname);

    void createUser(User user);

    void updateUser(User user);

    void removeUserById(Integer uid);
}

实现类UserServiceImpl.java

package com.jake.singlecandy.service.impl;

import com.jake.singlecandy.dao.UserDao;
import com.jake.singlecandy.pojo.User;
import com.jake.singlecandy.pojo.UserInfo;
import com.jake.singlecandy.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service("userService")
public class UserServiceImpl implements UserService {

    @Autowired
    private UserDao userDao;

    @Override
    public List<User> findAllUsers() {
        return userDao.findAllUsers();
    }

    @Override
    public List<User> findAllUserInfo() {
        return userDao.findAllUserInfo();
    }

    @Override
    public User findUserById(Integer uid) {
        return userDao.findUserById(uid);
    }

    @Override
    public UserInfo findUserInfoById(Integer uid) {
        return userDao.findUserInfoById(uid);
    }

    @Override
    public List<UserInfo> findUserInfoByUsernameAndCname(String username, String cname) {
        return userDao.findUserInfoByUsernameAndCname(username, cname);
    }

    @Override
    public void createUser(User user) {
        userDao.insertUser(user);
    }

    @Override
    public void updateUser(User user) {
        userDao.updateUser(user);
    }

    @Override
    public void removeUserById(Integer uid) {
        userDao.deleteUserById(uid);
    }

}

2.4 控制层

UserController.java

package com.jake.singlecandy.controller;

import com.jake.singlecandy.pojo.User;
import com.jake.singlecandy.pojo.UserInfo;
import com.jake.singlecandy.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@RestController
@RequestMapping("users")
public class UserController {

    @Autowired
    private UserService userService;

    /**
     * 查找所有用户
     * @return
     */
    @GetMapping
    public List<User> findAllUsers() {
        return userService.findAllUsers();
    }

    /**
     * 查找所有用户信息
     * @return
     */
    @GetMapping("info")
    public List<User> findAllUserInfo() {
        return userService.findAllUserInfo();
    }

    /**
     * 通过id查找用户
     * @param uid
     * @return
     */
    @GetMapping("{uid}")
    public User findUserById(@PathVariable Integer uid) {
        return userService.findUserById(uid);
    }

    /**
     * 通过id查找用户信息
     * @param uid
     * @return
     */
    @GetMapping("info/{uid}")
    public UserInfo findUserInfoById(@PathVariable Integer uid) {
        return userService.findUserInfoById(uid);
    }

    /**
     * 通过用户名和公司名查找用户
     * @param username
     * @param cname
     * @return
     */
    @GetMapping("info/{cname}/{username}")
    public List<UserInfo> findUserInfoByUsernameAndCname(@PathVariable String username, @PathVariable String cname) {
        return userService.findUserInfoByUsernameAndCname(username, cname);
    }

    /**
     * 新增用户
     * @param user
     * @return
     */
    @PostMapping
    public String createUser(@RequestBody User user) {
        if (user != null) {
            userService.createUser(user);
            return "添加用户成功";
        } else {
            return "添加用户失败";
        }
    }

    /**
     * 修改用户
     * @param user
     * @return
     */
    @PutMapping
    public String updateUser(@RequestBody User user) {
        User userInDb = userService.findUserById(user.getUid());
        if (userInDb != null) {
            userService.updateUser(user);
            return "更新用户成功";
        } else {
            return "更新用户失败";
        }
    }

    /**
     * 删除用户
     * @param uid
     * @return
     */
    @DeleteMapping("{uid}")
    public String removeUserById(@PathVariable Integer uid) {
        User user = userService.findUserById(uid);
        if (user == null) {
            return "数据库中不存在id为" + uid + "的用户";
        } else {
            userService.removeUserById(uid);
            return "删除成功";
        }
    }

}

三、前端测试

3.1 查找用户

HTTP请求方式选为GET
localhost:8084/singlecandy/users
localhost:8084/singlecandy/users/info
localhost:8084/singlecandy/users/1
localhost:8084/singlecandy/users/info/admin.com/admin

3.2 新增用户

HTTP请求方式选为POST，请求头选为Content-Type：application/json
localhost:8084/singlecandy/users/

{
	"username": "Jason Tang",
	"uid": 10
}

3.3 更新用户

HTTP请求方式选为PUT，请求头选为Content-Type：application/json
localhost:8084/singlecandy/users/

{
	"username": "Jason.Tang",
	"uid": 10
}

3.4 删除用户

HTTP请求方式选为DELETE
localhost:8084/singlecandy/users/10