Spring注解式声明事务相关问题
以下整理自己在使用Spring（3.1.1）注解式声明事务遇到的相关问题。
1、方法的访问权限只有在public时，@Transactional才会生效。
摘自http://docs.spring.io/spring/docs/3.2.12.RELEASE/spring-framework-reference/htmlsingle/
Methodvisibilityand@Transactional
Whenusingproxies,youshouldapplythe@Transactionalannotationonlytomethodswithpublicvisibility.Ifyoudoannotateprotected,privateorpackage-visiblemethodswiththe@Transactionalannotation,noerrorisraised,buttheannotatedmethoddoesnotexhibittheconfiguredtransactionalsettings.ConsidertheuseofAspectJ(seebelow)ifyouneedtoannotatenon-publicmethods.
2、同一个类中都声明@Transactional的方法调用，第二个方法的@Transactional不会生效。
摘自http://docs.spring.io/spring/docs/3.2.12.RELEASE/spring-framework-reference/htmlsingle/
Inproxymode(whichisthedefault),onlyexternalmethodcallscominginthroughtheproxyareintercepted.Thismeansthatself-invocation,ineffect,amethodwithinthetargetobjectcallinganothermethodofthetargetobject,willnotleadtoanactualtransactionatruntimeeveniftheinvokedmethodismarkedwith@Transactional.
3、嵌套事务（子事务以REQUIRES_NEW方式）造成数据库死锁
摘自http://stackoverflow.com/questions/17747906/getting-deadlock-found-when-trying-to-get-lock-try-restarting-transaction
MySQL'sInnoDBenginesportsrow-levellocking,whichcanleadtodeadlocksevenwhenyourcodeisinsertingorupdatingasinglerow(speciallyifthereareseveralindexesonthetablebeingupdated).Yourbestbetistodesignthecodearoundthisinordertoretryatransactionifitfailsduetoadeadlock.SomeusefulinfoaboutMySQLdeadlockdiagnoseandpossibleworkaroundsisavailablehere.
AninterestingimplementationofdeadlockretryviaAOPinSpringisavailablehere.Thiswayyoujustneedtoaddtheannotationtothemethodyouwanttoretryincaseofdeadlock.
4、在事务提交\事务回滚之后，处理一些事情。
// 在业务代码中，调用此代码
TransactionSynchronizationManager.registerSynchronization(new TransactionSynchronizationAdapter(){
// 重写afterCommit或者afterCompletion
// 在事务提交\事务回滚之后，就会执行
});