Mybatis

1.创建数据库表

CREATE DATAbase `mybatis`;

USE `mybatis`;

DROp TABLE IF EXISTS `user`;

CREATE TABLE `user` (
`id` int(20) NOT NULL,
`name` varchar(30) DEFAULT NULL,
`pwd` varchar(30) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert  into `user`(`id`,`name`,`pwd`) values (1,'狂神','123456'),(2,'张三','abcdef'),(3,'李四','987654');

2.导入mybatis依赖

            org.mybatis
            mybatis
            3.5.6
        

3.编写mybatis核心配置文件

4.编写Mybatis工具类

package com.bxb.utils;

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;

//SqlSessionFactory -->SqlSession
public class MybatisUtils {

    private static SqlSessionFactory sqlSessionFactory;

    static {

        try {
            //使用Mybatis第一步：获取sqlSessionFactory对象
            String resource = "mybatis-config.xml";
            InputStream inputStream = Resources.getResourceAsStream(resource);
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    //既然有了 SqlSessionFactory，顾名思义，我们可以从中获得 SqlSession 的实例。
    // SqlSession 提供了在数据库执行 SQL 命令所需的所有方法。你可以通过 SqlSession 实例来直接执行已映射的 SQL 语句。
    public static SqlSession getSqlSession() {
//        SqlSession sqlSession =  sqlSessionFactory.openSession();
//        return sqlSession;

        return sqlSessionFactory.openSession();
    }

}

5.编写实体类

package com.bxb.pojo;

//实体类
public class User {
    private int id;
    private String name;
    private String pwd;

    public User() {
    }

    public User(int id, String name, String pwd) {
        this.id = id;
        this.name = name;
        this.pwd = pwd;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getPwd() {
        return pwd;
    }

    public void setPwd(String pwd) {
        this.pwd = pwd;
    }

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", name='" + name + ''' +
                ", pwd='" + pwd + ''' +
                '}';
    }
}

6.编写UserDao接口

public interface UserDao {
    List getUserList();
}

7.编写Mapper配置文件

    
    
        select * from mybatis.user
    

8.junit测试

public class UserDaoTest {
    @Test
    public void test(){

        //1.获取SqlSession对象
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        //2.执行SQL
        // 方式一：getMapper
        UserDao userDao = sqlSession.getMapper(UserDao.class);
        List userList = userDao.getUserList();
        for (User user : userList) {
            System.out.println(user);
        }

        //关闭sqlSession
        sqlSession.close();
    }

}