mybatis基本配置与使用（在Test中）

文件结构

SqlMapCongfig.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>
    <environments default="mysql">
        <environment id="mysql">
            <transactionManager type="JDBC"></transactionManager>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis_db?serverTimezone=UTC"/>
                <property name="username" value="username"/>
                <property name="password" value="password"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/dao/UserDao.xml"></mapper>
    </mappers>
</configuration>

com中UserDao接口、mapper

UserDao.java

package com.dao;

import com.pojo.User;

import java.util.List;

public interface UserDao {
    List<User> findAll();
}

mapper 使用代理方式实现select

<?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.dao.UserDao">
    <!-- 查询全部 -->
    <select id="findAll" resultType="com.pojo.User">
        select * from USER
    </select>
</mapper>

resultType基本类型有很多写法。上面的是自定义的类型。

基本 逻辑 看test中的mybatisTest

package com.test;

import com.dao.UserDao;
import com.pojo.User;
import jdk.internal.util.xml.impl.Input;
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;

public class MybatisTest {
    public static void main(String[] args) throws IOException {
//        1.读取配置文件
//        创建Io流
        InputStream in = Resources.getResourceAsStream("SqlMapConfig.xml");
//        2.创建SqlSessionFactoryBuilder对象
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
//        3.创建SqlSessionFactory对象
        SqlSessionFactory factory = builder.build(in);
//        4.创建SqlSession对象
        SqlSession session = factory.openSession();
//        5.创建Dao接口的代理对象
        UserDao userDao = session.getMapper(UserDao.class);
//        6.执行方法
        List<User> users = userDao.findAll();
        for (User user:users){
            System.out.println(user);
        }
//        7.释放资源+提交事务
        session.close();
        in.close();
    }
}

别名应用
SqlMapConfig.xml

<typeAliases>
        <package name="com.pojo"/>
</typeAliases>

UserDao.xml

    <select id="findAll" resultType="uSeR">
        select * from USER
    </select>