Mybatis从零开始创建

1. 前期准备：

Mysql数据库

 2. IDEA中创建

1. 引入maven

• mybatis
• junit
• mysql-connector-java

    
        <dependency>
            <groupId>org.mybatisgroupId>
            <artifactId>mybatisartifactId>
            <version>3.5.7version>
        dependency>
 
        
        <dependency>
            <groupId>junitgroupId>
            <artifactId>junitartifactId>
            <version>4.12version>
            <scope>testscope>
        dependency>
 
        
        <dependency>
            <groupId>mysqlgroupId>
            <artifactId>mysql-connector-javaartifactId>
            <version>8.0.16version>
        dependency>

2. mybatis核心配置文件

• mybatis-config.xml
• jdbc.properties

   重点是environments和mappers标签

"1.0" encoding="UTF-8" ?>
configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">
 
<configuration>
 
    <properties resource="jdbc.properties">properties>
 
 
 
 
    <typeAliases >
        <typeAlias type="com.zt.mybatis.pojo.User" alias="abc">typeAlias>
        <typeAlias type="com.zt.mybatis.pojo.User">typeAlias>
        <package name="com.zt.mybatis.pojo"/>
    typeAliases>
    
    <environments default="development">
        <environment id="development">
 
            
            <transactionManager type="JDBC">transactionManager>
 
            
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"/>
                <property name="url" value="${jdbc.url}"/>
                <property name="username" value="${jdbc.username}"/>
                <property name="password" value="${jdbc.password}"/>
            dataSource>
        environment>
    environments>
 
    
    <mappers>
        <package name="com.zt.mybatis.mapper"/>
    mappers>
configuration>

jdbc.url=jdbc:mysql://localhost:3306/ibatis?useSSL=false&serverTimezone=UTC&characterEncoding=utf-8
jdbc.username=root
jdbc.password=xxxxx
jdbc.driver=com.mysql.cj.jdbc.Driver

3. Mapper接口

public interface UserMapper {
 
 
    /**
     *
     *当调用此方法进行插入的时候，根据接口名找到对应的映射文件，再找到映射文件中对应标签中与接口的方法名相同的id名
     */
 
    /**
     * 添加用户信息
     * @return
     */
     Integer insertUser();
}

4. sql映射文件Mapper(和上一步mapper接口命名一致)

• 接口的全类名和映射文件的namespace一致
• 接口的方法的方法名和映射文件中sql标签的id一致

"1.0" encoding="UTF-8" ?>
mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
 
<mapper namespace="com.zt.mybatis.mapper.UserMapper">
    
    <insert id="insertUser" >
        INSERT INTO t_user VALUES (NULL , 'admin', '123456', 23, '男', '12345@qq.com');
    insert>
 
mapper>

5. 测试

public class MybatisTest {
 
 
 
    @Test
    public void testInsert() throws IOException {
      // 获取核心配置文件的输入流
        InputStream resourceAsStream = Resources.getResourceAsStream("mybatis-config.xml");
 
        // 获取SqlSessionFactoryBuilder 对象 -> 工厂构建器
        SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
 
        // 创建 SqlSession 工厂 -> 创建会话
        SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(resourceAsStream);
 
        // 获取 会话 对象 -> MyBatis 提供的操作数据库的对象
        //如果没写commit 就不会自动提交
        SqlSession sqlSession = sqlSessionFactory.openSession();
 
    
 
        // 获得Mapper接口的代理类 -> 操纵Mapper类执行数据库操作
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
 
        // 执行SQL操作
        Integer rows = userMapper.insertUser();
//        User user = userMapper.selectUser();
//        System.out.println("rows = " + user);
        System.out.println("rows = " + rows);
 
        // 提交事务 -> 事务是默认开启的
        sqlSession.commit();
 
        // 关闭资源
        sqlSession.close();
    }
 
}