JDK动态代理实现原理

//?Decompiled?by?DJ?v3.11.11.95?Copyright?2009?Atanas?Neshkov??Date:?2012/8/9?20:11:32??//?Home?Page:?http://members.fortunecity.com/neshkov/dj.html??http://www.neshkov.com/dj.html?-?Check?often?for?new?version!??//?Decompiler?options:?packimports(3)?????import?dynamic.proxy.UserService;??import?java.lang.reflect.*;????public?final?class?$Proxy11?extends?Proxy??????implements?UserService??{????????//?构造方法，参数就是刚才传过来的MyInvocationHandler类的实例??????public?$Proxy11(InvocationHandler?invocationhandler)??????{??????????super(invocationhandler);??????}????????public?final?boolean?equals(Object?obj)??????{??????????try??????????{??????????????return?((Boolean)super.h.invoke(this,?m1,?new?Object[]?{??????????????????obj??????????????})).booleanValue();??????????}??????????catch(Error?_ex)?{?}??????????catch(Throwable?throwable)??????????{??????????????throw?new?UndeclaredThrowableException(throwable);??????????}??????}????????/**??????*?这个方法是关键部分??????*/??????public?final?void?add()??????{??????????try??????????{??????????????//?实际上就是调用MyInvocationHandler的public?Object?invoke(Object?proxy,?Method?method,?Object[]?args)方法，第二个问题就解决了??????????????super.h.invoke(this,?m3,?null);??????????????return;??????????}??????????catch(Error?_ex)?{?}??????????catch(Throwable?throwable)??????????{??????????????throw?new?UndeclaredThrowableException(throwable);??????????}??????}????????public?final?int?hashCode()??????{??????????try??????????{??????????????return?((Integer)super.h.invoke(this,?m0,?null)).intValue();??????????}??????????catch(Error?_ex)?{?}??????????catch(Throwable?throwable)??????????{??????????????throw?new?UndeclaredThrowableException(throwable);??????????}??????}????????public?final?String?toString()??????{??????????try??????????{??????????????return?(String)super.h.invoke(this,?m2,?null);??????????}??????????catch(Error?_ex)?{?}??????????catch(Throwable?throwable)??????????{??????????????throw?new?UndeclaredThrowableException(throwable);??????????}??????}????????private?static?Method?m1;??????private?static?Method?m3;??????private?static?Method?m0;??????private?static?Method?m2;????????//?在静态代码块中获取了4个方法：Object中的equals方法、UserService中的add方法、Object中的hashCode方法、Object中toString方法??????static???????{??????????try??????????{??????????????m1?=?Class.forName("java.lang.Object").getMethod("equals",?new?Class[]?{??????????????????Class.forName("java.lang.Object")??????????????});??????????????m3?=?Class.forName("dynamic.proxy.UserService").getMethod("add",?new?Class[0]);??????????????m0?=?Class.forName("java.lang.Object").getMethod("hashCode",?new?Class[0]);??????????????m2?=?Class.forName("java.lang.Object").getMethod("toString",?new?Class[0]);??????????}??????????catch(NoSuchMethodException?nosuchmethodexception)??????????{??????????????throw?new?NoSuchMethodError(nosuchmethodexception.getMessage());??????????}??????????catch(ClassNotFoundException?classnotfoundexception)??????????{??????????????throw?new?NoClassDefFoundError(classnotfoundexception.getMessage());??????????}??????}??}??



好了，到目前为止，前面 的两个问题都已经知道回事了，现在再用JDK动态代理的时候就不只会用而已了，真正的达到了“知其然，知其所以然”的目的。。

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转载：http://rejoy.iteye.com/blog/1627405