MyBatis —— 第二十三章 MyBatis 快速入门

---

MyBaits 官网地址：https://mybatis.org/mybatis-3/

MyBaits 开发步骤：

1. 添加 MyBaits 的 Maven 坐标
2. 创建 user 数据表
3. 编写 User 实体类
4. 编写映射文件 UserMapper.xml
5. 编写核心文件 sqlMapConfig.xml
6. 编写测试类

1. 添加 MyBaits 的 Maven 坐标

pom.xml

<dependencies>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>8.0.25</version>
    </dependency>
    <dependency>
        <groupId>org.mybatis</groupId>
        <artifactId>mybatis</artifactId>
        <version>3.5.5</version>
    </dependency>
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.13</version>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>log4j</groupId>
        <artifactId>log4j</artifactId>
        <version>1.2.16</version>
    </dependency>
</dependencies>

2. 创建 user 数据表

名	类型	长度	允许空值	是否主键
id	int	11	true	true
username	varchar	50	true	false
password	varchar	100	true	false

create table user
(
    id       int auto_increment
        primary key,
    username varchar(50)  not null,
    password varchar(100) not null,
    constraint user_id_uindex
        unique (id),
    constraint user_username_uindex
        unique (username)
);

3. 编写 User 实体类

com.yourname.domain.User

/**
 * @author gregPerlinLi
 * @since 2021-09-29
 */
public class User {
    private int id;
    private String username;
    private String password;

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                '}';
    }
}

4. 编写映射文件 UserMapper.xml

com/gregperlinli/mapper/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="userMapper">
    <select id="findAll" resultType="com.gregperlinli.domain.User">
        select * from user
    </select>
</mapper>

5. 编写核心文件 sqlMapConfig.xml

sqlMapConfig.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <!-- Data source environment -->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysq://localhost:3306/test"/>
                <property name="username" value="root"/>
                <property name="password" value="root"/>
            </dataSource>
        </environment>
    </environments>
    <!-- Load mapping profile -->
    <mappers>
        <mapper resource="com/gregperlinli/mapper/UserMapper.xml"></mapper>
    </mappers>
</configuration>

6. 编写测试类

com.yourname.test.MyBatisTest

/**
 * @author gregPerlinLi
 * @since 2021-09-29
 */
public class MyBatisTest {
        /**
     * Query operation
     * 
     * @throws IOException e
     */
    @Test
    public void test1() throws IOException {
        // Get core profile
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        // Get session factory object
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        // Get session object
        SqlSession sqlSession = sqlSessionFactory.openSession();
        // Execute operation    parameter: namespace + . + id
        List<User> userList = sqlSession.selectList("userMapper.findAll");
        // print data
        System.out.println(userList);
        // Release resources
        sqlSession.close();
    &#125;
&#125;

7. 知识要点

MyBaits 开发步骤

1. 添加 MyBaits 的 Maven 坐标
2. 创建 user 数据表
3. 编写 User 实体类
4. 编写映射文件 UserMapper.xml
5. 编写核心文件 sqlMapConfig.xml
6. 编写测试类

---