Mybatis的一二级缓存，一级缓存默认开启

1.可以知道的是Mybatis的一级缓存SqlSession默认是开启的。

2.可以自己去开启二级缓存在config.xml文件中的properties下面可以加上这个配置：

3.可以知道缓存之后的同一个session，再次执行操作的时候是不用再次查询数据库的。

resources下面建立这几个文件：

db.properties:

jdbc.driver=com.mysql.jdbc.Driver

jdbc.url=jdbc:mysql://localhost:3306/csjzjj

jdbc.username=root

jdbc.password=roothouzhicong

config.xml:

MyUserMapper:

package com.zjj.mapper;

import com.zjj.entity.MyUser;

import org.apache.ibatis.annotations.Select;

import java.util.List;

/**

* @Program mybatis

* @Package com.zjj.mapper

* @Auther TeacherHuang

* @Date 2021/8/16 15:29

* @Version 1.0

*/

public interface MyUserMapper {

@Select(“select *from myuser”)

List selectAll() throws Exception;

@Select(“select *from myuser”)

List selectAll01() throws Exception;

}

Test:

import com.zjj.entity.MyUser;

import com.zjj.mapper.MyUserMapper;

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.ioIOException;

import java.io.InputStream;

import java.util.List;

/**

* @Program mybatis

* @Package PACKAGE_NAME

* @Auther TeacherHuang

* @Date 2021/8/16 15:31

* @Version 1.0

*/

public class Test {

public static void main(String[] args) throws Exception {

String resources=”config.xml”;

InputStream inputstream = Resources.getResourceAsStream(resources);

SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputstream);

SqlSession session = sqlSessionFactory.openSession(true);

System.out.println(session);

MyUserMapper myUserMapper = session.getMapper(MyUserMapper.class);

System.out.println(“第一次没有缓存数据的时候———————“);

List myUsers = myUserMapper.selectAll();

System.out.println(myUsers);

// session.close();

session.clearCache();

System.out.println(“第二次没有缓存数据的时候———————“);

MyUserMapper myUserMapper02 = session.getMapper(MyUserMapper.class);

List myUsers01 = myUserMapper.selectAll();

System.out.println(myUsers01);

}

}