java - how to listen the special class initialization? -

here want listen special classes initialization; when classess initialization actions.

present want use interface or annotation, how implement this?

we have solved problem，we use javassist;the code likes:

configuration conf = (configuration) entry.getvalue();         string clazz = conf.getclazz();            try {         ctclass ctclass = classpool.getdefault().get(clazz);         string appendcode = "{com.broada.bsp.gene.config.management.configurationmanager.manager.inject(this);\n}";         ctconstructor constructor[] = ctclass.getdeclaredconstructors();          (ctconstructor ctconstructor : constructor) {             ctconstructor.insertafter(appendcode);         }              ctclass.toclass(); 

thank answers, himanshu bhardwaj !

here can not use solutions,because can not change users new java object actions, use javassist, append come code after constructors, users java new objects,needn't change behaves.