SpringBoot整合Mybatis

在介绍整合Mybatis 前，我们先介绍下如何使用传统的Dao 类方式来实现

首先，配置maven

<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>com.fasterxml.jackson.core</groupId>
			<artifactId>jackson-databind</artifactId>
		</dependency>
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>fastjson</artifactId>
			<version>1.2.47</version>
		</dependency>
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<version>8.0.19</version>
		</dependency>
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>2.1.2</version>
		</dependency>
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid-spring-boot-starter</artifactId>
			<version>1.1.10</version>
		</dependency>
		<dependency>

然后我们在application.properties 中进行配置

spring.datasource.type=com.alibaba.druid.pool.DruidDataSource
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/mybatis_db?useUnicode=true&characterEncoding=utf-8
spring.datasource.username=root
spring.datasource.password=123456

接下来我们创建一个User 类

public class User {
    private Integer id;
    private String username;
    private String jobs;
    private String phone;
    //get
    //set

然后创建一个UserDao 类

@Repository
public class UserDao {
    @Autowired
    JdbcTemplate jdbcTemplate;

    public int addUser(User user){
        return jdbcTemplate.update("INSERT INTO t_user(username,jobs,phone) VALUE (?,?,?)",
                user.getName(),user.getJobs(),user.getPhone());
    }
    public int updateUser(User user){
        return jdbcTemplate.update("UPDATE t_user SET username=?,jobs=?,phone=? WHERE id=?",
                user.getName(),user.getJobs(),user.getPhone(),user.getId());
    }
    public int deleteUser(Integer id){
        return jdbcTemplate.update("DELETE  FROM t_user WHERE id=?",id);
    }
    public User getUserById(Integer id){
        return jdbcTemplate.queryForObject("SELECT * FROM t_user WHERE id =?",new BeanPropertyRowMapper<>(User.class),id);
    }
    public List<User> getAllUser(){
        return jdbcTemplate.query("SELECT * FROM t_user",new BeanPropertyRowMapper<>(User.class));
    }
}

接下来创建一个UserService 类

@Service
public class UserService {

    @Autowired
    UserDao userDao;
    public int addUser(User user){
        return userDao.addUser(user);
    }
    public int updateUser(User user){
        return userDao.updateUser(user);
    }
    public int deleteUser(Integer id){
        return userDao.deleteUser(id);
    }
    public  User getUserById(Integer id){
        return userDao.getUserById(id);
    }
    public List<User> getAllUser(){
        return userDao.getAllUser();
    }
}

最后是UserController类

@RestController
public class UserController {
    @Autowired
    UserService userService;
    @GetMapping("/user")
    public void UserOps(){
        User u1 = new User();
        u1.setName("章三三");
        u1.setJobs("程序员");
        u1.setPhone("131444224433");
        int i = userService.addUser(u1);
        System.out.println(i);
        List<User> allUser = userService.getAllUser();
        System.out.println(allUser);
    }
}

我们运行程序，然后访问127.0.0.1:8080/user 我们看到IDE 控制台输出了如下内容

访问数据库，我们查询后结果如下

这是传统Dao 方式的整合，接下来，我们讲下使用Mybatis 整合

首先，在pom.xml 中增加

<dependency>
    <groupId>org.mybatis.spring.boot</groupId>
    <artifactId>mybatis-spring-boot-starter</artifactId>
    <version>2.1.2</version>
</dependency>

然后创建一个Mapper 文件夹，在该文件夹下创建一个UserMapper 接口

@Mapper
public interface UserMapper {
     int addUser(User user);
     int deleteUser(int id);
     int updateUser(User user);
     User getUserById(Integer id);
     List<User> getAllUsers();

}

接下来，在resource下创建一个Mapper 文件夹，然后在文件夹中创建一个UserMapper.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.example.demo.Mapper.UserMapper">
    <insert id="addUser" parameterType="com.example.demo.Bean.User">
        INSERT INTO t_user(username,jobs,phone) VALUE (#{username},#{jobs},#{phone})
    </insert>
    <delete id="deleteUser" parameterType="int">
        DELETE FROM t_user WHERE id=#{id}
    </delete>
    <update id="updateUser" parameterType="com.example.demo.Bean.User">
        UPDATE t_user set username=#{username},jobs=#{jobs},phone=#{phone} WHERE id=#{id}
    </update>
    <select id="getUserById" parameterType="int" resultType="com.example.demo.Bean.User">
        SELECT * FROM t_user WHEN id=#{id}
    </select>
    <select id="getAllUsers" resultType="com.example.demo.Bean.User">
        SELECT * FROM t_user
    </select>
</mapper>

然后对之前的UserService 类进行改造

@Service
public class UserService {

    @Autowired
    UserMapper userMapper;
    public int addUser(User user){
        return userMapper.addUser(user);
    }
    public int updateUser(User user){
        return userMapper.updateUser(user);
    }
    public int deleteUser(Integer id){
        return userMapper.deleteUser(id);
    }
    public  User getUserById(Integer id){
        return userMapper.getUserById(id);
    }
    public List<User> getAllUser(){
        return userMapper.getAllUsers();
    }
}

然后我们在application.properties中添加mybatis 的配置

mybatis.typeAliasesPackage=com.example.demo.Mapper
mybatis.mapperLocations=classpath:Mapper/*.xml

最后，我们修改下UserController

@RestController
public class UserController {
    @Autowired
    UserService userService;
    @GetMapping("/user")
    public void UserOps(){
        User u1 = new User();
        u1.setName("李思思");
        u1.setJobs("美工");
        u1.setPhone("131444224443");
        int i = userService.addUser(u1);
        System.out.println(i);
        List<User> allUser = userService.getAllUser();
        System.out.println(allUser);
    }
}

运行程序，我们访问结果如下

查询数据库

整个工程的目录结构如下