<mapper namespace="com.cn.inter.IMessageOperation">
<select id="selectUserByID" parameterType="int" resultType="com.cn.imooc.entity.Message">
select * from `message` where id = #{id}
</select>
<select id="selectMessages" resultType="Message">
select id,
command,
description,
comment
from message;
</select>
</mapper>

package com.cn.test;
import java.io.Reader;
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 com.cn.imooc.entity.Message;
import com.cn.inter.IMessageOperation;
public class MyTest2 {
public static void main(String[] args) {
// TODO Auto-generated method stub
Reader reader;
SqlSession sqlSession=null;
try{
//从类路径下（src）读取mybatis配置文件
reader=Resources.getResourceAsReader("Configuration.xml");
SqlSessionFactory sqlSessionFactory=new SqlSessionFactoryBuilder().build(reader);
sqlSession=sqlSessionFactory.openSession();
//获得IMessageOperation接口
IMessageOperation imo=sqlSession.getMapper(IMessageOperation.class);
//调用接口的方法返回查询结果
Message message=imo.selectMessageByIdI(new Integer(3));
System.out.println(message);
}
catch(Exception e){
e.printStackTrace();
}finally{
//如果sqlSession不为空，则关闭
if(null!=sqlSession)
sqlSession.close();
}
}
}