關(guān)于緩存問(wèn)題：

http://www.cnblogs.com/zemliu/archive/2013/08/05/3239014.html

執(zhí)行了2次sql查詢,看似我們使用了同一個(gè)sqlSession,但是實(shí)際上因?yàn)槲覀兊膁ao繼承了SqlSessionDaoSupport,而SqlSessionDaoSupport內(nèi)部sqlSession的實(shí)現(xiàn)是使用用動(dòng)態(tài)代理實(shí)現(xiàn)的,這個(gè)動(dòng)態(tài)代理sqlSessionProxy使用一個(gè)模板方法封裝了select()等操作,每一次select()查詢都會(huì)自動(dòng)先執(zhí)行openSession(),執(zhí)行完close()以后調(diào)用close()方法,相當(dāng)于生成了一個(gè)新的session實(shí)例,所以我們無(wú)需手動(dòng)的去關(guān)閉這個(gè)session()(關(guān)于這一點(diǎn)見(jiàn)下面mybatis的官方文檔),當(dāng)然也無(wú)法使用mybatis的一級(jí)緩存,也就是說(shuō)mybatis的一級(jí)緩存在spring中是沒(méi)有作用的.

官方文檔摘要

MyBatis?SqlSession?provides you with specific methods to handle transactions programmatically. But when using MyBatis-Spring your beans will be injected with a Spring managed?SqlSession?or a Spring managed mapper. That means that Spring will?always?handle your transactions.

You cannot call?SqlSession.commit(),?SqlSession.rollback()?or?SqlSession.close()?over a Spring managed?SqlSession. If you try to do so, a?UnsupportedOperationException?exception will be thrown. Note these methods are not exposed in injected mapper classes.

會(huì)重新創(chuàng)建一個(gè)新的sqlSession，因?yàn)槊看蔚臄?shù)據(jù)庫(kù)操作，一般都是以下四步：

1，獲取SqlSession對(duì)象

2，調(diào)用數(shù)據(jù)庫(kù)操作的方法

3，提交事務(wù)

4，關(guān)閉SqlSession