The AOP of Java

AOP (aspect-oriented programming), the official definition will not speak, but Baidu itself. As I understand it, the code fragment is injected dynamically into a certain piece of code that is known. The advantage of this is that the functionality of the original business can be expanded without changing the original code.

AOP is implemented in two ways:

1. Dynamic Agent

Example:

Let's say we print a row of logs for each method entry and exit of a class, but we can't change the original code.

1  Packagecom;2 3  Public InterfaceALGORITHMITF4 {5 voidAdd ();6 7 voiddel ();8 9 voidupdate ();Ten  One voidfind (); A } -  -  Packagecom; the  -  Public classAlgorithmImplementsALGORITHMITF - { -  Public voidAdd () + { -System.out.println ("Add ..."); + } A  Public voiddel () at { -System.out.println ("Del ..."); - } -  Public voidUpdate () - { -SYSTEM.OUT.PRINTLN ("Update ..."); in } -  Public voidFind () to { +System.out.println ("Find ..."); - } the } *  $  Panax Notoginseng  -  Packagecom; the  + ImportJava.lang.reflect.InvocationHandler; A ImportJava.lang.reflect.Method; the ImportJava.lang.reflect.Proxy; +  -  Public classAopdyproxy<t>ImplementsInvocationhandler $ { $ PrivateT o; -  -  PublicT CreateInstance (T T) the { -o=T;Wuyi returnT (Proxy.newproxyinstance (O.getclass (). getClassLoader (), O.getclass (). Getinterfaces (), This)); the } -  Wu @Override -  PublicObject Invoke (Object proxy, Method method, object[] args)throwsThrowable About { $Object re=NULL; -System.out.println (Method.getname () + "enter"); -Re=Method.invoke (o, args); -System.out.println (Method.getname () + "Exit"); A returnre; + } the  Public Static voidMain (string[] args) - { $Aopdyproxy<algorithmitf> p=NewAopdyproxy<algorithmitf>(); theALGORITHMITF A=p.createinstance (Newalgorithm ()); the A.add (); the a.update (); the } -  in}

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2. Static Proxy

The AOP of Java