mybatis的入门步骤，适合初学者，复制就可用

如何mybatis步骤

    <!--    导入依赖-->
    <dependencies>
<!--        mysql驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.28</version>
        </dependency>
<!--        Mybatis-->
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.2.5</version>
        </dependency>
<!--        junit-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
            <scope>test</scope>
        </dependency>

    </dependencies>

在resource下面新建一个mybatis的配置文件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核心配置文件-->
<configuration>
    <!--数据库环境-->
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="com.mysql.jdbc.Driver"/>
                <property name="url" value="jdbc:mysql://localhost:3306/mybatis?useUnicode=true&characterEncoding=utf8&serverTimezone=GMT%2B8&useSSL=false"/>
                <property name="username" value="root"/>
                <property name="password" value="123456"/>
            </dataSource>
        </environment>
    </environments>
    <!--映射文件-->
    <mappers>
        <mapper resource="com/learn/ssm/chapter3/mapper/RoleMapper.xml"/>
    </mappers>
</configuration>

在java里面utils工具类下面建立mybatis的第一步，这是固定的，必须写：

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

import javax.annotation.Resource;
import java.io.InputStream;

//工具类。获取sqlSessionFactory----->sqlsession
public class MybatisUtils {
    public static SqlSessionFactory sqlSessionFactory;


    static {     //使用mybatis第一步：获取SqlSessionFactory对象
        String resource="mybatis-config.xml";
        InputStream inputStream=Resource.class.getResourceAsStream(resource);
        sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
    }

    //目的就是为了得到这个sqlSession
    public static SqlSession getSqlSession(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        return sqlSession;
    }
}

编写数据库对应的实体类pojo下面

package com.mac.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 + '\'' +
                '}';
    }
}

去Dao包下面建立接口和配置文件，也可以包名叫Mapper
UserDao

package com.mac.dao;

import com.mac.pojo.User;

import java.util.List;
//查询全部用户
public interface UserDao {
    List<User> getUserList();
}

<!--namespace绑定一个对应的Dao或者Mapper借口-->

<!-- id,就是之前的方法  resultType,上一个方法放回类型的老家 -->

<?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">


<!--namespace绑定一个对应的Dao或者Mapper借口-->
<mapper namespace="com.mac.dao.UserDao">
<!-- id,就是之前的方法  resultType,上一个方法放回类型的老家 -->
    <select id="getUserList" resultType="com.mac.pojo.User">
        select * from mybatis.user
    </select>
</mapper>

然后就可以进行测试了
在test下建立对应的测试文件进行
记得报名建立和我的对应

UserDaoTest

package com.mac.dao;

import com.mac.pojo.User;
import com.mac.utils.MybatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import java.util.List;

public class UserDaoTest {
    @Test
    public void Test(){
        //1:先获取SqlSession
        SqlSession sqlSession = MybatisUtils.getSqlSession();

        //2执行Sql        通过放射得到UserDao，然后执行方法
        UserDao mapper = sqlSession.getMapper(UserDao.class);
        List<User> userList = mapper.getUserList();

        for (User user : userList) {
            System.out.println(user);
        }
        //3:关闭Sqlsession
        sqlSession.close();
    }
}