Mybatis

在Java文件中

package com.itheima.mapper;
import com.itheima.pojo.User;
import java.util.List;
public interface UserMapper {
    List selectAll();
}

在resources下建立文件夹跟接口同名称目录的UserMapper.xml并且修改命名空间。

编写UserMapper.xml

    
    select * from tb_user;
  

编写mybatis-config.xml

扫描包的方式可以扫描该文件夹目录下的所有mapper。

"/>

public class MybatisDemo2 {
    public static void main(String[] args) throws IOException {
        //1.加载Mybatis核心配置文件，获取SqlSessionFactory
        String resource = "mybatis-config.xml";
        InputStream inputStream = Resources.getResourceAsStream(resource);
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);

        //2.获取sqlsession对象，用它来执行sql
        SqlSession sqlSession = sqlSessionFactory.openSession();
        
        //3获取UserMapper接口的代理对象
        UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
        List users = userMapper.selectAll();
        System.out.println(users);

        //3.1释放资源
        sqlSession.close();
    }
}