使用Mybatis框架(xml)

结构：

 

Pojo实体类，对应mysql表的结构

 mapper，将sql映射成方法，通过demo去调用sql方法

XXXmaaper.xml里面写了具体的sql

logback.xml、mybatis.xml配置信息

使用mapper去代理开发要将XXXmapper.xml配置和mapper方法类放在同一目录下

 

XXXmapper.xml具体类的配置：

<?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.leehl.mapper.UserMapper">
    <select id="selectAll" resultType="com.leehl.pojo.User">
        select * from tb_user
    </select>
</mapper>

mybatis-config.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>

        <!--default的值的变成另外数据库的id名，下面是development，如果有个test库，可以改成default=test，xml好处就在可以随意切换-->

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <!--数据库连接信息-->
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://192.168.10.128:3306/mybatis?useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <!--sql的映射文件-->
<!--        <mapper resource="com/leehl/mapper/UserMapper.xml"/>-->

        <!--sql的映射文件,如果用mapper代理开发的话只要扫描包就行-->
        <package name="com.leehl.mapper"/>
    </mappers>
</configuration>

 

运行简而言之：

通过输入流InputStream读取mybatis-config文件去构建SqlsessionFactory，

通过SqlsessionFactory去构建sqlsession，然后用sqlsession对象去打开对象流，opensession

然后用sqlsession去运行sql

package com.leehl;

import com.leehl.mapper.UserMapper;
import com.leehl.pojo.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

/**
 * @author 82365
 * @version 1.0
 * @description TODO
 * @date 2023/6/10 11:22
 */

public class MyBatisDemo2 {
    public static void main(String[] args) throws IOException {
        //加载mybatis配置文件，通过配置文件构建sqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //获取sqlSession对象，用sqlSession来执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();

        //使用sqlSession的getmapper去执行sql
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<User> userList = mapper.selectAll();


        System.out.println(userList);
        //关闭session
        sqlSession.close();


    }
}

 

 

mybatis中文文档：

https://mybatis.net.cn/getting-started.html