对mybatis缓存机制的断点跟踪

package com.cy.test;

import java.util.List;

import org.apache.ibatis.session.SqlSession;
import org.junit.Test;

import com.cy.pj.goods.dao.GoodsDao;
import com.cy.pj.goods.pojo.Goods;

public class MyTestCache01 extends TestBaseWithJava{
	/**
	 * 测试一级缓存,过程断点跟踪一定要明白
	 */
	@Test
	//对于同一session来说,开二级缓存
	public void testFirstLevelCache() {
		//1.获取SqlSession对象
		SqlSession session=sqlSessionFactory.openSession();
		//2.执行删除业务
		GoodsDao dao=session.getMapper(GoodsDao.class);
		List<Goods> list=dao.findPageObjects(0, 3);//第一次去数据库取数据
		//3.提交事务
		session.commit();
		list=dao.findPageObjects(0,3);//第二次走一级cache,从中取数据
		System.out.println("list.size="+list.size());
		for(Goods g:list) {
			System.out.println(g);
		}
//		//3.提交事务
//		session.commit();//这里边要是开二级缓存的话session.commit()应放在22-25之间因为不提交或者关闭数据部会进入二级缓存中
		//4.释放资源
		session.close();
	}
	@Test
	//对于同一session来说,不开二级缓存
	public void testFirstLevelCache1() {
		/**--对于一级缓存来说,session.commit();或者session.close();
		 *--一级缓存都会失效因为其作用范围仅仅在一次会话中,注意session.commit()和session.close();的位置--*/
		//1.获取SqlSession对象
		SqlSession session=sqlSessionFactory.openSession();
		//2.执行删除业务
		GoodsDao dao=session.getMapper(GoodsDao.class);
		List<Goods> list=dao.findPageObjects(0, 3);//第一次去数据库取数据
		list=dao.findPageObjects(0,3);//第二次走一级cache,从中取数据
		System.out.println("list.size="+list.size());
		for(Goods g:list) {
			System.out.println(g);
		}
//		//3.提交事务
		session.commit();
		/**这里边要是开二级缓存的话session.commit()
		 *应放在22-25之间因为不提交或者关闭数据部会进入二级缓存中*/
		//4.释放资源
		session.close();
	}
	@Test
	//对于不同session来说
	public void testSecondLevelCache() {
		//1.获取SqlSession对象
		SqlSession session1=sqlSessionFactory.openSession();
		SqlSession session2=sqlSessionFactory.openSession();
		//2.执行删除业务
		GoodsDao dao1=session1.getMapper(GoodsDao.class);
		GoodsDao dao2=session2.getMapper(GoodsDao.class);
		List<Goods> list1=dao1.findPageObjects(0, 3);
		session1.commit();//一级缓存失效
		List<Goods> list2=dao2.findPageObjects(0, 3);//第二次走cache
		//3.提交事务
		session2.commit();//先从二级拿拿不到再从一级拿,还是拿不到就从数据库中查询
		//4.释放资源
		session1.close();
		session2.close();
	}
}

断点跟踪可以清晰的显示出cache缓存的运行顺序

配置文件

<?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">
<mapper namespace="com.cy.pj.goods.dao.GoodsDao">
 	<cache eviction="fifo" readOnly="true" > </cache>
 	<!-- readonly是设置是否要存储序列化的对象,因为cache也是内存所以也可以存非序列化的对象-->
 	<!--eviction可设置算法选项为FIFO和LRU-->
 	<!--flushInterval=""设置刷新时间-->
 	<!--size=""设置可以存的引用(对象)的数量-->
    <!-- 基于多个id进行删除操作 方法1 -->
    <!--  
    <delete id="deleteObjects">
        delete from tb_goods
        where id in 
        <foreach collection="array"
                 open="("
                 close=")"
                 item="id"
                 separator=",">
                #{id}
        </foreach> 
    </delete>
    -->
    <!-- 基于多个id进行删除操作:方法2 -->
    <delete id="deleteObjects">
        delete from tb_goods
        <where>
         <foreach collection="array"
                 item="id">
                or id=#{id} 
         </foreach> 
        </where>  
    </delete>
    
    <select id="findPageObjects"
            resultType="com.cy.pj.goods.pojo.Goods">
       select id,name,remark,createdTime
       from tb_goods
       limit #{startIndex},#{pageSize}
    </select>
    
   <select id="selectById"
            resultType="com.cy.pj.goods.pojo.Goods">
       select id,name,remark,createdTime
       from tb_goods
       where id=#{id}
    </select>
    
    
    <delete id="deleteObject">
         delete from tb_goods
         where id=#{id}
    </delete>
    
    <!-- 映射文件中每个元素都会封装一个MappedStatement对象 -->
    <insert id="insertObject"
            parameterType="com.cy.pj.goods.pojo.Goods">
       insert into tb_goods
       (id,name,remark,createdTime)
       values
       (#{id},#{name},#{remark},now())
    </insert>
    <!-- 映射文件中每个元素都会封装一个MappedStatement对象 -->
    <update id="updateObject">
        update tb_goods
        set name=#{name},
            remark=#{remark}
        where id=#{id}
    </update>
</mapper>