ClassloadersandJBOSS-GoogleCode：类加载器和JBoss-谷歌代码

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1、ClassloadersandJBOSSObjectivesYouwillunderstandwhyclassloaderareimportantinJ2EEenvironments.Youwillin-depthknowledgeofclassloaders.YouwilllearnabouttheJ2EEclassloaderhierarchyanditsimplications.YouwilllearnabouttheJbossclassloaderimplementationClassloaderbasicsSample

2、ClassillustratingtheinfluenceofClassloaderspublicclassPerson{privateStringfirstName;privateStringlastName;publicbooleanequals(Objectobj){booleanreturnValue=false;if(obj.getClass().equals(Person.class)){Personperson=(Person)obj;if(person.getFirstName().equals(this.fir

3、stName)&&person.getLastName().equals(this.lastName)){returnValue=true;}}returnreturnValue;}}CommonClassloadersExceptionsClassCastExceptionNoClassDefFoundErrorClassloaderPrinciplesOperationsDelegationPrinciple:Ifaclassisnotloadedalready,theclassloadersdelegatethereque

4、sttoloadthatclasstotheirparentclassloaders.VisibilityPriniciple:Classesloadedbyparentclassloadersarevisibletochildclassloadersbutnotviceversa.UniquenessPrinciple:Whenaclassloaderloadsaclass,thechildclassloadersinthehierarchywillneverreloadthatclass.DelegationPrincipl

5、eVisibilityPrincipleUniquenessPrinciple01publicclassX{03publicX(){04ClassLoadercl=this.getClass().getClassLoader();05ClassB=Class.forName(“B”,true,cl);06}J2EEClassloaderhierarchyJ2EEClassloaderhierarchyJ2EEClassloaderhierarchyifanEJBapplicationwantstoreferenceutil-a.

6、jarandutil-b.jar,thenwecanaddthefollowingentryintotheEJB-JAR’smanifestfile,MANIFEST.MF.Class-Path:util-a.jarutil-b.jarJBOSSClassloadingHierarchy