package me.gacl.test;
import me.gacl.domain.User;
import me.gacl.util.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.junit.Test;
/**
* @author gacl
* 測(cè)試一級(jí)緩存
*/
public class TestOneLevelCache {
/*
* 一級(jí)緩存: 也就Session級(jí)的緩存(默認(rèn)開(kāi)啟)
*/
@Test
public void testCache() {
SqlSession session = MyBatisUtil.getSqlSession();
String statement = "me.gacl.mapping.userMapper.getUser";
User user = session.selectOne(statement, );
System.out.println(user);
/*
* 一級(jí)緩存默認(rèn)就會(huì)被使用
*/
user = session.selectOne(statement, );
System.out.println(user);
session.close();
/*
. 必須是同一個(gè)Session,如果session對(duì)象已經(jīng)close()過(guò)了就不可能用了 
*/
session = MyBatisUtil.getSqlSession();
user = session.selectOne(statement, );
System.out.println(user);
/*
. 查詢條件是一樣的
*/
user = session.selectOne(statement, );
System.out.println(user);
/*
. 沒(méi)有執(zhí)行過(guò)session.clearCache()清理緩存
*/
//session.clearCache(); 
user = session.selectOne(statement, );
System.out.println(user);
/*
. 沒(méi)有執(zhí)行過(guò)增刪改的操作(這些操作都會(huì)清理緩存)
*/
session.update("me.gacl.mapping.userMapper.updateUser",
new User(, "user", ));
user = session.selectOne(statement, );
System.out.println(user);
}
} 

<mapper namespace="me.gacl.mapping.userMapper">
<!-- 開(kāi)啟二級(jí)緩存 -->
<cache/> 

package me.gacl.test;
import me.gacl.domain.User;
import me.gacl.util.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.junit.Test;
/**
* @author gacl
* 測(cè)試二級(jí)緩存
*/
public class TestTwoLevelCache {
/*
* 測(cè)試二級(jí)緩存
* 使用兩個(gè)不同的SqlSession對(duì)象去執(zhí)行相同查詢條件的查詢，第二次查詢時(shí)不會(huì)再發(fā)送SQL語(yǔ)句，而是直接從緩存中取出數(shù)據(jù)
*/
@Test
public void testCache() {
String statement = "me.gacl.mapping.userMapper.getUser";
SqlSessionFactory factory = MyBatisUtil.getSqlSessionFactory();
//開(kāi)啟兩個(gè)不同的SqlSession
SqlSession session = factory.openSession();
SqlSession session = factory.openSession();
//使用二級(jí)緩存時(shí)，User類必須實(shí)現(xiàn)一個(gè)Serializable接口===> User implements Serializable
User user = session.selectOne(statement, );
session.commit();//不懂為啥，這個(gè)地方一定要提交事務(wù)之后二級(jí)緩存才會(huì)起作用
System.out.println("user="+user);
//由于使用的是兩個(gè)不同的SqlSession對(duì)象，所以即使查詢條件相同，一級(jí)緩存也不會(huì)開(kāi)啟使用
user = session.selectOne(statement, );
//session.commit();
System.out.println("user="+user);
}
} 

<cache 
eviction="FIFO" <!--回收策略為先進(jìn)先出-->
flushInterval="60000" <!--自動(dòng)刷新時(shí)間60s-->
size="512" <!--最多緩存512個(gè)引用對(duì)象-->
readOnly="true"/> <!--只讀-->