首先resources下的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">
<!--核心配置文件-->
<configuration><environments default="development"><environment id="development"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="com.mysql.cj.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/ssms?useSSL=true&amp;useUnicode=true&amp;characterEncoding=UTF-8"/><property name="username" value="root"/><property name="password" value="123456"/></dataSource></environment></environments><mappers><mapper resource="cn/zmxy/dao/UsersMapper.xml"/></mappers>
</configuration>

pojo实现类层的Java类(对应数据库表),比如Users表

public class Users {private int id;private String name;private String pwd;

  public Users(){}

}

dao层的映射xml和Interface接口

UsersMapper.xml

<?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 命名空间 保定一个对应的dao/mapper接口-->
<mapper namespace="cn.zmxy.dao.UsersMapper"><select id="getUserList" resultType="cn.zmxy.pojo.Users">
  SELECT * FROM ssms.users
    </select><select id="getUserById" resultType="cn.zmxy.pojo.Users" parameterType="int">
  SELECT * FROM ssms.users WHERE id = #{id}
  </select><insert id="addUser" parameterType="cn.zmxy.pojo.Users">
  INSERT INTO ssms.users (id, name, pwd) VALUES (#{id}, #{name}, #{pwd})
    </insert><update id="updateUser" parameterType="cn.zmxy.pojo.Users">
  UPDATE ssms.users SET name = #{name}, pwd = #{pwd} WHERE id = #{id}
  </update><delete id="deleteUser" parameterType="int">
  DELETE FROM ssms.users WHERE id = #{id}
  </delete>
</mapper>

UsersMapper.java

package cn.zmxy.dao;
import cn.zmxy.pojo.Users;
import java.util.List;

public interface UsersMapper {

  // 查询全部用户public List<Users> getUserList();

  // 根据ID查询用户public Users getUserById(int id);

  // 添加用户public int addUser(Users user);

  // 修改用户public int updateUser(Users user);

  // 删除用户public int deleteUser(int id);
}

写一个utils类，获取SqlSession

MyBatisUtils.java

package cn.zmxy.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;

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 (IOException e) {
  e.printStackTrace();} }public static SqlSession getSqlSession(){  return sqlSessionFactory.openSession();}}

最后就可以调用了，写一个test类

UserMapperTest.java

package cn.zmxy.dao;
import cn.zmxy.pojo.Users;
import cn.zmxy.utils.MyBatisUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
import java.util.List;

public class UserDaoTest {@Testpublic void test(){  // 第一步，获取SqlSession对象SqlSession sqlSession = MyBatisUtils.getSqlSession();// 第二步，执行SQLUsersMapper usersMapper = sqlSession.getMapper(UsersMapper.class);List<Users> userList = usersMapper.getUserList();

  // 打印usersfor (Users users : userList) {System.out.println(users);}  // 关闭SqlSession
  sqlSession.close();}@Testpublic void getUserById(){  // 第一步，获取SqlSession对象SqlSession sqlSession = MyBatisUtils.getSqlSession();UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);

  Users user = mapper.getUserById(1);System.out.println(user);// 关闭SqlSession
  sqlSession.close();}@Testpublic void addUser(){  // 第一步，获取SqlSession对象SqlSession sqlSession = MyBatisUtils.getSqlSession();UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);

  int num = mapper.addUser(new Users(0, "露露", "1234"));System.out.println("受影响行数：" + num);
  sqlSession.commit();// 关闭SqlSession
  sqlSession.close();}@Testpublic void updateUser(){  // 第一步，获取SqlSession对象SqlSession sqlSession = MyBatisUtils.getSqlSession();UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);

  int num = mapper.updateUser(new Users(3, "露露", "1234"));System.out.println("受影响行数：" + num);
  sqlSession.commit();// 关闭SqlSession
  sqlSession.close();}@Testpublic void deleteUser(){  // 第一步，获取SqlSession对象SqlSession sqlSession = MyBatisUtils.getSqlSession();UsersMapper mapper = sqlSession.getMapper(UsersMapper.class);

  int num = mapper.deleteUser(11);System.out.println("受影响行数：" + num);
  sqlSession.commit();// 关闭SqlSession
  sqlSession.close();}
}