/*如果已经存在此数据库，先删除*/

drop database if exists sqltest  ;

/*创建并设置编码为UTF-8*/

create database sqltest default character set utf8 ;

/*选择数据库*/

use sqltest ;

/*删除已有的学生表*/

drop table if exists tb_student ;

/*创建学生表*/

CREATE TABLE `tb_student` (

  `id` int(11) NOT NULL AUTO_INCREMENT,

  `stuId` varchar(45) DEFAULT NULL,

  `name` varchar(45) DEFAULT NULL,

  `clsId` varchar(45) DEFAULT NULL,

  PRIMARY KEY (`id`)

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

/*插入学生的数据*/

insert into tb_student (stuId,name,clsId) value ('','张三','') ;

insert into tb_student (stuId,name,clsId) value ('','李四','') ;

insert into tb_student (stuId,name,clsId) value ('','王五','') ;

insert into tb_student (stuId,name,clsId) value ('','赵六','') ;

insert into tb_student (stuId,name,clsId) value ('','巩发财','') ;

insert into tb_student (stuId,name,clsId) value ('','柏拉图','') ;

insert into tb_student (stuId,name,clsId) value ('','钱老虎','') ;

insert into tb_student (stuId,name,clsId) value ('','杨伟','') ;

insert into tb_student (stuId,name,clsId) value ('','陈海','') ;

package org.yoki.edu.main.vo;

public class Student {

    private Integer id;

    private String stuId;

    private String name;

    private String clsId;

    /*省略setter、getter方法*/

}

<?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>

    <!-- typeAliases必须写在environments和mappers前面，不然报错，这是dtd格式限制的 -->

    <typeAliases>

        <!-- 用于在实体类的映射文件进行使用student，而不用每次使用类的全名 -->

        <typeAlias type="org.yoki.edu.main.vo.Student" alias="student" />

    </typeAliases>

    <environments default="development">

        <environment id="development">

            <transactionManager type="JDBC" />

            <!-- 数据库链接信息，注：分号改为&amp;转义符，防止报错 -->

            <dataSource type="POOLED">

                <property name="driver" value="com.mysql.jdbc.Driver" />

                <property name="url" value="jdbc:mysql://localhost:3306/sqltest?useUnicode=true&amp;characterEncoding=UTF-8&amp;useSSL=false" />

                <property name="username" value="root" />

                <property name="password" value="root" />

            </dataSource>

        </environment>

    </environments>

    <mappers>

        <!-- 实体类的映射文件 -->

        <mapper resource="org/yoki/edu/main/vo/StudentMapper.xml" />

    </mappers>

</configuration>

<?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随意内容 -->

<mapper namespace="this.is.student.mapper.namespace">

    <!-- 方法一 -->

    <!-- type属性对应与在MyBatis配置文件中typeAliases标签下定义的引用 -->

    <resultMap id="studentMapper" type="student">

    <!-- 属性名称<>列名 -->

        <id property="id" column="id" />

        <result property="stuId" column="stuId" />

        <result property="name" column="name" />

        <result property="clsId" column="clsId" />

    </resultMap>

    <!-- resultMap属性值对应 -->

    <select id="selectById" resultMap="studentMapper">

        select * from tb_student where id = #{id}

    </select>

    <!-- 方法二 -->

    <!-- resultType可以使用类的全名，也可以使用MyBatis配置文件中typeAliases标签下定义的引用 -->

<!--     <select id="selectById" resultType="org.yoki.edu.main.vo.Student"> -->

<!--         select * from tb_student where id = #{id} -->

<!--     </select> -->

</mapper>

package org.yoki.edu.utils;

import java.io.IOException;

import java.io.InputStream;

import org.apache.ibatis.io.Resources;

import org.apache.ibatis.session.SqlSession;

import org.apache.ibatis.session.SqlSessionFactory;

import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class SessionUtils {

    private static SqlSessionFactory fa = null ;

    static{

        /*静态代码块，在类加载后执行*/

        String resource = "org/yoki/edu/utils/mybatis-config.xml" ;

        InputStream input;

        try {

            /*获取配置文件的输入流*/

            input = Resources.getResourceAsStream(resource);

            /*根据输入流生成SqlSessionFactory*/

            fa = new SqlSessionFactoryBuilder().build(input) ;

            int j = 0 ;

        } catch (IOException e) {

            e.printStackTrace();

        }

    }

    public SqlSession getSqlSession(){

        if(null == fa)

            return null;

        SqlSession session = fa.openSession() ;

        return session ;

    }

}

package org.yoki.edu.main.dao;

import org.apache.ibatis.session.SqlSession;

import org.yoki.edu.main.vo.Student;

import org.yoki.edu.utils.SessionUtils;

public class StudentDao {

    private SessionUtils utils = new SessionUtils() ;

    public Student getById(Integer id){

        SqlSession session = utils.getSqlSession() ;

        /*selectOne的第一个参数对应映射文件的namespace + '.' + （select、update、insert、delete）id*/

        Student st = session.selectOne("this.is.student.mapper.namespace" + ".selectById", id) ;

        return st ;

    }

}

package org.yoki.edu.main;

import org.yoki.edu.main.dao.StudentDao;

import org.yoki.edu.main.vo.Student;

public class MainRun {

    public static void main(String[] args) {

        StudentDao dao = new StudentDao() ;

        Student st = dao.getById(2) ;

        System.out.println(st);

    }

}