簡介：英文原文英文原文JAVAISASIMPLE,OBJECTORIENTED,DISTRIBUTED,INTERPRETED,ROBUSTSECURITY,STRUCTURENEUTRAL,PORTABLE,HIGHPERFORMANCE,MULTITHREADEDDYNAMICLANGUAGETHEMAINADVANTAGEOFJAVALANGUAGE,JAVAAPPLICATIONSACROSSHARDWAREPLATFORMSANDOPERATINGSYSTEMSFORTRANSPLANTTHISISBECAUSETHEJVMISINSTALLEDONEACHPLATFORMCANUNDERSTANDTHESAMEBYTECODEJAVALANGUAGEANDPLATFORMSCALABILITYISVERYSTRONGATTHELOWEND,JAVALANGUAGEISTHEFIRSTOPENSTANDARDSTECHNOLOGYSUPPORTENTERPRISEONE,SUPPORTTHEUSEOFXMLANDWEBSERVICECANNOTSTRIDEBUSINESSLINESTOSHAREINFORMATIONANDAPPLICATIONSCHENGXUTHEREARETHREEVERSIONSOFJAVAPLATFORM,WHICHMAKESSOFTWAREDEVELOPERS,SERVICEPROVIDERSANDEQUIPMENTMANUFACTURERSCANTARGETSPECIFICMARKETDEVELOPMENT1JAVASEFORMAPPLICATIONSJAVASEINCLUDESSUPPORTFORJAVAWEBSERVICESDEVELOPMENTCLASSES,ANDFORTHEJAVAPLATFORM,ENTERPRISEEDITIONJAVAEETOPROVIDEABASISMOSTJAVADEVELOPERSUSEJAVASE5,ALSOKNOWNASJAVA50OR“TIGER“2JAVAEEFORMERLYKNOWNASJ2EEENTERPRISEEDITIONTOHELPDEVELOPANDDEPLOYPORTABLE,ROBUST,SCALABLEANDSECURESERVERSIDEJAVAAPPLICATIONSJAVASEJAVAEEISBUILTONTHEFOUNDATION,WHICHPROVIDESWEBSERVICES,COMPONENTMODEL,MANAGEMENTANDCOMMUNICATIONAPI,CANBEUSEDTOACHIEVEENTERPRISECLASSSERVICEORIENTEDARCHITECTUREANDWEB20APPLICATIONS3JAVAMEFORMERLYKNOWNASJ2MEJAVAMEDEVICESINMOBILEANDEMBEDDEDAPPLICATIONSRUNNINGONAROBUSTANDFLEXIBLEENVIRONMENTJAVAMEINCLUDESFLEXIBLEUSERINTERFACES,ROBUSTSECURITYMODEL,ANDMANYBUILTINNETWORKPROTOCOLSANDNETWORKINGTHATCANBEDYNAMICALLYDOWNLOADEDANDEXTENSIVESUPPORTFOROFFLINEAPPLICATIONSJAVAMEBASEDAPPLICATIONSPECIFICATIONONLYWRITEONCEANDCANBEUSEDINMANYDEVICESANDCANUSETHENATIVEFEATURESOFEACHDEVICEJAVALANGUAGEISSIMPLEJAVALANGUAGESYNTAXANDTHECLANGUAGEANDCLANGUAGEISVERYCLOSE,JAVADISCARDEDTHEC,RARELYUSED,HARDTOUNDERSTANDTHECHARACTERISTICS,SUCHASOPERATOROVERLOADING,MULTIPLEINHERITANCE,THEMANDATORYAUTOMATICTYPECONVERSIONJAVALANGUAGEDOESNOTUSEPOINTERS,ANDPROVIDESAUTOMATEDWASTECOLLECTIONJAVAISANOBJECTORIENTEDLANGUAGEJAVALANGUAGEPROVIDESCLASSES,INTERFACESANDINHERITANCEOFTHEORIGINALLANGUAGE,FORSIMPLICITY,ONLYSUPPORTSSINGLEINHERITANCEBETWEENCLASSES,BUTSUPPORTMULTIPLEINHERITANCEBETWEENINTERFACESANDSUPPORTCLASSESANDINTERFACESTOACHIEVEBETWEENTHEMECHANISMKEYWORDIMPLEMENTSJAVALANGUAGEFULLYSUPPORTSDYNAMICBINDING,ANDCLANGUAGEUSEDONLYFORDYNAMICBINDINGOFVIRTUALFUNCTIONSINSHORT,JAVALANGUAGEISAPUREOBJECTORIENTEDPROGRAMMINGLANGUAGEJAVALANGUAGEISDISTRIBUTEDJAVALANGUAGESUPPORTFORINTERNETAPPLICATIONDEVELOPMENT,JAVASRMIREMOTEMETHODACTIVATIONMECHANISMISALSOANIMPORTANTMEANSOFDEVELOPINGDISTRIBUTEDAPPLICATIONSJAVALANGUAGEISROBUSTJAVASSTRONGTYPESYSTEM,EXCEPTIONHANDLING,AUTOMATEDWASTECOLLECTIONISANIMPORTANTGUARANTEEROBUSTJAVAPROGRAMSJAVALANGUAGEISSAFEJAVAISOFTENUSEDINNETWORKENVIRONMENT,THIS,JAVAPROVIDESASECURITYMECHANISMTOPREVENTMALICIOUSCODEATTACKSHIBERNATESECONDAGAINSTTHECONDITIONSOFTHEQUERYCACHEHIBERNATEOBJECTRELATIONALMAPPINGFORTHEDELAYANDNONDELAYOBJECTINITIALIZATIONNONLAZYWHENREADINGANOBJECTANDTHEOBJECTWILLBEALLREADOUTTOGETHERWITHOTHEROBJECTSTHISSOMETIMESRESULTSINHUNDREDSIFNOTTHOUSANDSOFWORDSSELECTSTATEMENTWHENREADINGTHEOBJECTIMPLEMENTATIONTHISPROBLEMSOMETIMESOCCURSWHENUSINGTHETWOWAYRELATIONSHIP,OFTENLEADINGTOTHEDATABASESTOBEREADDURINGTHEINITIALIZATIONPHASEOUTOFCOURSE,YOUCANTAKETHETROUBLETOEXAMINEEACHOBJECTANDOTHEROBJECTSOFGUANXI,ANDTOTHEMOSTEXPENSIVEOFTHESHANCHU,BUTINTHELAST,WEMAYTHEREFORELOSELEORMTOOLTHISXIANGZAIOBTAINEDBIANLIACACHEANDSECONDARYCACHEOFCOMPARISONTHEFIRSTLEVELCACHESECONDLEVELCACHEDATASTOREDINTHEFORMOFINTERRELATEDPERSISTENTOBJECTSTHEOBJECTOFBULKDATACACHERANGEOFTHESCOPEOFSERVICES,EACHTRANSACTIONHASASEPARATEFIRSTLEVELCACHEPROCESSRANGEORSCOPEOFTHECLUSTER,THECACHEISTHESAMEPROCESSORCLUSTERTOSHAREONALLMATTERSWITHINTHECONCURRENTACCESSPOLICIESBECAUSEEACHTRANSACTIONHASASEPARATEFIRSTLEVELCACHE,CONCURRENCYPROBLEMDOESNOTOCCURWITHOUTTHENEEDTOPROVIDECONCURRENTACCESSPOLICYWILLBEANUMBEROFMATTERSSIMULTANEOUSACCESSTOTHESAMESECONDLEVELCACHEDATA,ITISNECESSARYTOPROVIDEAPPROPRIATECONCURRENTACCESSPOLICIES,TOENSURETHATAPARTICULARTRANSACTIONISOLATIONLEVELDATAEXPIRATIONPOLICIESDIDNOTPROVIDEDATAEXPIRATIONPOLICIESOBJECTINACACHEWILLNEVEREXPIRE,UNLESSTHEAPPLICATIONEXPLICITLYCLEARTHECACHEORCLEARASPECIFICOBJECTMUSTPROVIDEDATAEXPIRATIONPOLICIES,SUCHASMEMORYCACHEBASEDONTHEMAXIMUMNUMBEROFOBJECTS,ALLOWINGOBJECTSINTHECACHEOFTHEMOSTALONGTIME,ANDALLOWINGTHEOBJECTINTHECACHETHELONGESTIDLETIMEOFPHYSICALMEMORYANDHARDDISKMEMORYSTORAGEMEDIUMFIRSTOFALLBULKDATAOBJECTSSTOREDINTHEMEMORYBASEDCACHE,WHENTHENUMBEROFOBJECTSINMEMORYTODATAEXPIRATIONPOLICYSPECIFIEDLIMIT,THEREMAININGOBJECTSWILLBEWRITTENONTHEHARDDISKCACHECACHINGSOFTWAREIMPLEMENTATIONOFTHEHIBERNATESESSIONISINCLUDEDINTHEREALIZATIONOFTHECACHEPROVIDEDBYTHIRDPARTIES,HIBERNATEPROVIDESONLYACACHEADAPTERCACHEPROVIDERUSEDTOPLUGINTOAPARTICULARCACHEINHIBERNATEWAYCACHEENABLEDAPPLICATIONSBYASLONGASTHESESSIONINTERFACEIMPLEMENTATIONSAVE,UPDATE,DELETE,DATALOADINGANDQUERYTHEDATABASEOPERATIONS,HIBERNATEWILLENABLEFIRSTLEVELCACHE,THEDATAINTHEDATABASEINTHEFORMOFANOBJECTCOPIEDTOTHECACHEFORBATCHUPDATESANDBULKDELETEOPERATIONS,IFYOUDONOTWANTTOENABLEFIRSTLEVELCACHE,YOUCANBYPASSTHEHIBERNATEAPI,JDBCAPIDIRECTLYTOPERFORMTHATOPERATIONUSERSCANTYPEINASINGLECLASSORASINGLESETOFSECONDLEVELCACHESIZEONTHECONFIGURATIONIFTHEINSTANCEOFTHECLASSAREFREQUENTLYREADBUTRARELYMODIFIED,YOUCANCONSIDERUSINGASECONDLEVELCACHEONLYFORACLASSORSETOFSECONDLEVELCACHEISCONFIGURED,HIBERNATEWILLRUNWHENANINSTANCEOFITTOTHESECONDLEVELCACHEUSERMANAGEMENTMEANSTHEFIRSTLEVELCACHEOFPHYSICALMEDIAFORTHEMEMORYCACHE,BECAUSETHEMEMORYCAPACITYISLIMITED,MUSTPASSTHEAPPROPRIATESEARCHSTRATEGIESANDRETRIEVALMETHODSTOLIMITTHENUMBEROFOBJECTSLOADEDSESSIONOFTHEEVITMETHODCANEXPLICITLYCLEARTHECACHEASPECIFICOBJECT,BUTTHISMETHODISNOTRECOMMENDEDSECONDLEVELCACHEMEMORYANDTHEPHYSICALMEDIACANBEAHARDDISK,SOTHESECOND
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上傳時(shí)間：2024-03-17
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