Mybatis根据用户ID查询数据

根据用户ID查询数据 1，修改映射配置文件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"> <mapper namespace="com.lying.mapper.UserMapper"> <!--根据用户ID查询用户--> <select id="selectUsersById" parameterType="int" resultType="com.lying.pojo.Users" > select * from users where userid=#{suibian} </select> </mapper>

2，修改UserDao接口 UserDao.java

package com.lying.dao; import com.lying.pojo.Users; import java.io.IOException; import java.util.List; /** * @Author:Lying * @Date:2020/8/30 * @Description:com.lying.dao * @version:1.0 */ public interface UsersDao { Users selectUsersById(int userid) throws IOException; }

3，修改UserDao接口实现类 UserDaoImpl.java

package com.lying.dao.com.lying.dao.impl; import com.lying.dao.UsersDao; import com.lying.pojo.Users; 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; import java.util.List; /** * @Author:Lying * @Date:2020/8/30 * @Description:com.lying.dao.com.lying.dao.impl * @version:1.0 */ public class UsersDaoImpl implements UsersDao { /** * 根据用户ID查询用户 * @param userid * @return * @throws IOException */ @Override public Users selectUsersById(int userid) throws IOException { //创建SqlSessionFactory对象 InputStream inputStream=Resources.getResourceAsStream("mybatis-cfg.xml"); SqlSessionFactory sqlSessionFactory= new SqlSessionFactoryBuilder().build(inputStream); //获取SqlSession对象 SqlSession sqlSession =sqlSessionFactory.openSession(); Users users=sqlSession.selectOne("com.lying.mapper.UserMapper.selectUsersById",userid); sqlSession.close(); return users; } }

4，修改测试类 Test.java

package com.lying.test; import com.lying.dao.UsersDao; import com.lying.dao.com.lying.dao.impl.UsersDaoImpl; import com.lying.pojo.Users; import java.io.IOException; import java.util.List; /** * @Author:Lying * @Date:2020/9/1 * @Description:com.lying.test * @version:1.0 */ public class Test { public static void main(String[] args) throws IOException { UsersDao usersDao=new UsersDaoImpl(); Users users=usersDao.selectUsersById(1); System.out.println(users.getUserid()+"\t"+users.getUsername()+"\t"+users.getUsersex()); } }