MyBatis环境搭建

官网下载Mybatis框架

https://mybatis.org/mybatis-3/zh/getting-started.html

编写MyBatis核心配置文件

<?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>

<!--2.配置MyBatis框架的运行环境-->

    <environments default="development">

        <environment id="development">

            <!--配置事务管理器，采用JDBC事务，由应用自行管理事务-->

            <transactionManager type="JDBC"/>

            <!--配置数据源，POOLED:MyBatis提供的数据源，JNDI：JNDI数据源-->

            <dataSource type="POOLED">

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

                <property name="url" value="jdbc:mysql://127.0.0.1:3306/conveniencestoresanagementsystem?useUnicode=true&amp;characterEncoding=utf8&amp;serverTimezone=Asia/Shanghai"/>

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

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

            </dataSource>

        </environment>

</environments>

<!-- 指定映射配置文件的位置，映射配置文件指的是每个dao独立的配置文件 -->

    <mappers>

        <mapper resource="com/mapper/SysUSerMapper.xml"/>

    </mappers>

</configuration>

编写MyBatis工具类

package com.util;

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 MyBatisUtil {

    //核心配置文件路径

    private static String CONFIG_FILE = "mybatis-config.xml";

//SqlSession工厂

    private static SqlSessionFactory factory;

//加载核心配置文件路径并初始化SqlSession工厂

  static {

      try {

          InputStream stream = Resources.getResourceAsStream(CONFIG_FILE);

          factory = new SqlSessionFactoryBuilder().build(stream);

      } catch (IOException e) {

          e.printStackTrace();

      }

    }

//根据SqlSession工厂获取SqlSession对象

  public static SqlSession getSqlSession(){

      return factory.openSession();

    }

//关闭SqlSession链接

    public static void close(SqlSession sqlSession){

      if (sqlSession!=null){

          sqlSession.close();

      }

    }

}

编写dao接口

package com.dao;

public interface SysUserDao {

    //查询用户数量

    public int count();

}

编写mapper映射文件

<?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">

<!--

namespace:表示抽象类地址

select:表示查询

id:表示抽象类方法名称

resultType:表示返回值类型

-->

<mapper namespace="com.dao.SysUserDao">

    <select id="count" resultType="int">

        select count(*) from `t_sys_user`

    </select>

</mapper>

编写测试类

package com.dao;

import com.util.MyBatisUtil;

import org.apache.ibatis.session.SqlSession;

import org.junit.jupiter.api.Test;

import java.util.List;

class SysUserDaoTest {

    @Test

    void count() {

        //获取SqlSession链接

        SqlSession sqlSession = MyBatisUtil.getSqlSession();

        //同过SqlSession映射SysUserDao

        SysUserDao mapper = sqlSession.getMapper(SysUserDao.class);

        //执行SysUserDao并返回结果

        System.out.println("mapper.count() = " + mapper.count());

        //关闭链接

        sqlSession.close();

    }

}

返回结果

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