MyBatis：缓存（狂神）

 

操作步骤：

 

 

 

 

 

 

 

 do.properties：

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/mybatis?useSSL=&useUnicode=true&characterEncoding=utf-8
username=root
password=123456

mybatis-config.xml:

User:

package com.kuang.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

import java.io.Serializable;

@Data
@AllArgsConstructor
@NoArgsConstructor
public class User implements Serializable {
    private int id;
    private String name;
    private String pwd;
}

UserMapper:

package com.kuang.dao;

import com.kuang.pojo.User;
import org.apache.ibatis.annotations.Param;

public interface UserMapper {
    //查询指定用户
    User queryUserById(@Param("id") int id);

    int updateUser(User user);
}

UserMapper.xml:

    

    
    


    
         select * from user11 where id=#{id}
    

    
        update mybatis.user11 set name=#{name},pwd=#{pwd} where id=#{id}
    

MyTest:

import com.kuang.dao.UserMapper;
import com.kuang.pojo.User;
import com.kuang.utils.MybaitsUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

public class MyTest {
    //一级缓存
    @Test
    public void queryUserById(){
        SqlSession sqlSession= MybaitsUtils.getSqlSession();
        UserMapper mapper=sqlSession.getMapper(UserMapper.class);

        User user = mapper.queryUserById(1);
        System.out.println(user);
        //mapper.updateUser(new User(2,"张三2","123456"));//增删改会更新缓存

        sqlSession.clearCache();//手动清理缓存

        System.out.println("================");
        User user2=mapper.queryUserById(1);
        System.out.println(user2);

        System.out.println(user==user2);

        sqlSession.close();
    }
    //二级缓存
    @Test
    public void test2(){
        SqlSession sqlSession= MybaitsUtils.getSqlSession();
        SqlSession sqlSession2= MybaitsUtils.getSqlSession();
        UserMapper mapper=sqlSession.getMapper(UserMapper.class);

        User user = mapper.queryUserById(1);
        System.out.println(user);
        sqlSession.close();

        System.out.println("================");
        UserMapper mapper2=sqlSession2.getMapper(UserMapper.class);
        User user2=mapper2.queryUserById(1);//从二级缓存中获取
        System.out.println(user2);

        User user3=mapper2.queryUserById(2);
        System.out.println(user3);

        User user4=mapper2.queryUserById(2);
        System.out.println(user4);//一级缓存中获取
        

        System.out.println(user==user2);
        sqlSession2.close();


    }
}

一次sqlSession开启一级缓存 

 添加更新操作，打开注释，刷新缓存：

手动清理缓存，注释更新，打开注释： 

 二级缓存：

缓存原理

 自定义缓存：

 需要创建一个ehcache.xml：