maven 仓库：

<dependency>
    <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.46</version>
</dependency>

<dependency>
    <groupId>org.mybatis</groupId>
    <artifactId>mybatis</artifactId>
    <version>3.5.2</version>
</dependency>

<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
</dependency>

1.首先编写 Mabatis工具类：

package com.wang.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.InputStream;

public class MybatisUtils {
    private static  SqlSessionFactory sqlSessionFactory;
    static {
        try {
            String resource="mybatis-config.xml";
            InputStream is = Resources.getResourceAsStream(resource);
            sqlSessionFactory=new SqlSessionFactoryBuilder().build(is);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
    public  static SqlSession getSqlSession(){
        return  sqlSessionFactory.openSession();
    }
}
在其中准备连接数据库所需资源（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>
    <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/wang?useUnicode=true&amp;characterEncoding=UTF-8" />
                <property name="username" value="root" />
                <property name="password" value="123456" />
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/wang/dao/UserMapp.xml"></mapper>
    </mappers>
</configuration>

注：在mybatis-config.xml文件中 需要与第二步中的Mapp建立联系，格式如下：

    <mappers>
        <mapper resource="com/wang/dao/UserMapp.xml"></mapper>
    </mappers>

2.编写Dao中文件：（Dao接口，Mapp.xml）
Dao接口文件：可以在已添加接口

package com.wang.dao;

import com.wang.Pojo.User;
import java.util.List;
public interface UserDao {
 List<User> getUser();//查

int  insertUser(User user);//增
int  deleteUser(String id);//删
int  updatetUser(User user);//改

}
Mapp.xml文件:

<?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.wang.dao.UserDao">
    <select id="getUser"  resultType="com.wang.Pojo.User">
        SELECT * FROM user
    </select>

<insert id="insertUser" parameterType="com.wang.Pojo.User" >
    insert into user(id,name,email) value (#{id},#{name} ,#{email})
</insert>
<update id="updatetUser" parameterType="com.wang.Pojo.User" >
    update user set name=#{name},email=#{email}  where id=#{id}
</update>
<delete id="deleteUser" parameterType="String">
    delete  from user where id=#{id}
</delete>

</mapper>

注：其中nameSpace是Dao接口的文件
       id为Dao接口中的方法
       resultType为返回结果的类型


3.编写主程序：

//第一步，用工具类获取sqlSession。
SqlSession sqlSession = MybatisUtils.getSqlSession();
//第二步，获取Dao对象
UserDao userDao = sqlSession.getMapper(UserDao.class);
//第三步，通过Dao对象调用其中的方法，返回集合
//        int num = userDao.insertUser(new User("09", "haha", "999"));

//        int num = userDao.updatetUser(new User("09", "lalala", "888"));
//        int num = userDao.deleteUser("09");
//        List<User> list = userDao.getUser();
//        for(User u:list){
//            System.out.println(u.toString());
//        }
 sqlSession.commit();//除查询之外，其他操作必须要有事务提交，否则不会更新表

sqlSession.close();//关闭资源

声明：（Mapp.xml导出资源问题）：需要在pom.xml文件添加以下代码：

<build>
    <resources>
        <resource>
            <directory>src/main/resources</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>

        <resource>
            <directory>src/main/java</directory>
            <includes>
                <include>**/*.properties</include>
                <include>**/*.xml</include>
            </includes>
            <filtering>true</filtering>
        </resource>
    </resources>
</build>

Mybatis建立连接

原文：https://www.cnblogs.com/wanglala/p/13399055.html