MyBatis 03

Posted 2021-01-12 一纸流年

接下来我们把配置信息罗列一下 
主配置文件：SqlMapConfig.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">  
<configuration>  
    <environments default="development">  
        <environment id="development">
        <transactionManager type="JDBC"/>  
            <dataSource type="POOLED">  
                <property name="driver" value="com.mysql.jdbc.Driver" />  
                <property name="url" value="jdbc:mysql://localhost:3306/demo" />  
                <property name="username" value="root" />  
                <property name="password" value="123" />  
            </dataSource>  
        </environment>  
    </environments>  

    <!-- 加载映射文件 -->  
    <mappers>  
        <mapper resource="com/demo/entity/EmpMapper.xml" />  
    </mappers>  
</configuration>  

EmpMapper.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.demo.entity.emp">
    <select id="findbyid" resultType="com.demo.entity.emp">
        select * from emp
    </select>    
</mapper>

接下来是写一个Test来测验一下，因为此次只是测试session的创建，所一并未执行查询语句。

package com.demo.entity;

import java.io.InputStream;

import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class Test {
    public static void main(String []args){

        String resource="config.xml";
        //获得输入流
        InputStream inputStream=
                Test.class.getClassLoader()
                .getResourceAsStream(resource);
        //获得SqlSessionFactoryBuilder对象
        SqlSessionFactoryBuilder builder=
                new SqlSessionFactoryBuilder();
        //获得SqlSessionFactory
        SqlSessionFactory factory=builder.build(inputStream);
        //获得session
        SqlSession session = factory.openSession();
        System.out.println("success!");
        session.close();

    }


}

控制台输出：

success!

这里我们可以做一些简单的封装，可以做一个对SqlSession返回对象的一个封装。废话不多说，直接上code：

package com.demo.Utils;
import java.io.InputStream;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
public class MybatisUtil {
     public static SqlSession getSqlSession(){
         String resource = "SqlMapConfig.xml";
         InputStream is = MybatisUtil.class.getClassLoader().getResourceAsStream(resource);
         SqlSessionFactory sessionFactory = new SqlSessionFactoryBuilder().build(is);
         SqlSession session = sessionFactory.openSession();
         return session;
     }

}

这样一个Utils就完成了，如果以后需要获取SqlSession对象，直接调用就好了。

然后写一个Test：

package Test;
import org.apache.ibatis.session.SqlSession;
import com.demo.Utils.MybatisUtil;
public class TestEmp {
    public static void main(String[] args){
        SqlSession session = MybatisUtil.getSqlSession();
        System.out.println("use session ");
        session.close();

    }

}

控制台输出：

use session 

这样我们就获取到了SqlSession对象。 

 

 

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