java同步机制（java同步机制）

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1、java同步机制（java同步机制）JavaJssupportandsynchronizationmechanismformultithreadingislovedbyeveryone,anditseemsthatitiseasytosolvetheproblemofmultithreadsharingofdatasynchronizationusingthesynchronizedkeyword・Sowhat?Alsohavetosynchronizedkeywordroleindepthunderstanding,canbeconelusive・Ingeneral

2、,thesynchronizedkeywordcanbeusedasafunctionmodifierorasafunctionstatement,thatis,asynchronousmethodandasynchronousstatementblock.Forfurtherclassification,synchronizedcanworkoninstancevariables,object,reference(objectreferences),staticfunctions,andclassliterals(classnames,literalconstant

3、s).Beforeweelaborate,weneedtomakesomespecificpoints:A.regardlessofthesynchronizedkeywordaddedtothemethodorobject,thelockitobtainsistheobject,nottheobjectApieceofcodeorfunctionthatactsasalock一andthesynchronizationmethodislikelytobeaccessedbyotherthreadobjects.B.eachobjecthasonlyonelock(l

4、ock)associatedwithit.C.synchronizationiscostlyattheexpenseofthesystemandcanevencausedeadlocks,soavoidunnecessarysynchronization.Next,discusstheimpactofsynchronizedoncodegenerationindifferentplaces:SupposethatPlandP2aredifferentobjectsofthesameclass,inwhichthesynchronizationblocksorsynch

5、ronizationmethodsaredefined,andPlandP2cancallthem・1.whensynchronizedisusedasafunctionmodifier,thesamplecodeisasfollows:Public,synchronized,void,methodAAA()Thisisthesynchronizationmethod,sowhatobjectdoessynchronizedlockatthistime?Itlockstheobjectthatcallsthissynchronizationmethod.Thatist

6、osay,whenanobjectPlexecutesthissynchronizationmethodindifferentthreads,theyformmutualexclusionandachievesynchronization.However,anotherobjectP2generatedbytheClasstowhichtheobjectbelongsbelongstosynchronizedcanbecalledarbitrarily.Thesamplecodeaboveisequivalenttothefollowingcode:Public,vo

7、id,methodAAA()Synchronized(this)/(1)(1)whatdoes"this"mean?Itreferstotheobjectthatcallsthismethod,suchasPl.Itisobviousthatthesynchronizationmethodessentiallyappliessynchronizedtoobjectreference・-thegetthePlobjectlockthreadsynchronizationcancallthePlmethod,andforP2,thePllockandit