Java-proxy is when to call Invocationhandler's Invoke method

Recently saw spring dynamic agent, grilled to the depths to see when proxy.newproxyinstance (ClassLoader, proxiedinterfaces, this); see this sentence, suddenly more confused force, Still didn't understand the invocation of the Invoke method, and then searched for a moment, and met a great God article

Special to record, hey: First here is the original link

In fact, the front can be omitted (too late, to sleep), what to create an interface, implement a class, create a class that implements Invocationhandler (not create a row), and so on, the direct focus, the proxy object to execute the Invoke place:

First, we compile, we will come up with a proxy object class file, open the class file to solve the puzzle (at that time is also crazy, this trick didn't think, ah haha):

In our proxy class, there is a protected Invocationhandler member property:

 Public classProxyImplementsjava.io.Serializable {Private Static Final LongSerialversionuid = -2222568056686623797l; /**parameter types of a proxy class constructor*/    Private Static Finalclass<?>[] Constructorparams ={Invocationhandler.class }; /*** A cache of proxy classes*/    Private Static FinalWeakcache<classloader, class<?>[], class<?>>Proxyclasscache=NewWeakcache<> (NewKeyfactory (),Newproxyclassfactory ()); /*** The invocation handler for this proxy instance. * @serial     */    protectedInvocationhandler h;//is here! /*** prohibits instantiation. */    PrivateProxy () {}/*** Constructs a new {@codeProxy} instance from a subclass * (typically, a dynamic Proxy Class) with the specified value * for its INVOC     ation handler. *     * @paramh The invocation handler for this proxy instance * *@throwsNullPointerException If the given invocation handler, {@codeh}, * is {@codenull}. */    protectedProxy (Invocationhandler h) {objects.requirenonnull (h);  This. H =h; }

Then look at the implementation of the proxy object:

 Public Final class$Proxy 0extendsProxyImplementsSubject (target class, class being proxied) {Private StaticMethod M1; Private StaticMethod M0; Private StaticMethod m3; Private StaticMethod m2; Static {          Try{M1= Class.forName ("Java.lang.Object"). GetMethod ("equals"),                      NewClass[] {class.forname ("Java.lang.Object") }); M0= Class.forName ("Java.lang.Object"). GetMethod ("Hashcode"),                      NewClass[0]); M3= Class.forName ("* * *. Realsubject "). GetMethod (" Request ",//proxy method nameNewClass[0]); M2= Class.forName ("Java.lang.Object"). GetMethod ("toString"),                      NewClass[0]); } Catch(nosuchmethodexception nosuchmethodexception) {Throw NewNosuchmethoderror (Nosuchmethodexception.getmessage ()); } Catch(ClassNotFoundException classnotfoundexception) {Throw NewNoclassdeffounderror (Classnotfoundexception.getmessage ()); }      } //Static       Public$Proxy 0 (Invocationhandler invocationhandler) {Super(Invocationhandler); } @Override Public Final Booleanequals (Object obj) {Try {              return((Boolean)Super. H.invoke ( This, M1,Newobject[] {obj}))          . Booleanvalue (); } Catch(Throwable throwable) {Throw Newundeclaredthrowableexception (Throwable); }} @Override Public Final inthashcode () {Try {              return(Integer)Super. H.invoke ( This, M0,NULL) . Intvalue (); } Catch(Throwable throwable) {Throw Newundeclaredthrowableexception (Throwable); }      }         Public Final voidrequest () {//proxy methodTry {              Super. H.invoke ( This, M3,NULL); return; } Catch(Error e) {}Catch(Throwable throwable) {Throw Newundeclaredthrowableexception (Throwable); }} @Override Public FinalString toString () {Try {              return(String)Super. H.invoke ( This, M2,NULL); } Catch(Throwable throwable) {Throw Newundeclaredthrowableexception (Throwable); }      }  }  

See here to understand. The newly returned proxy object, called the Parent Class (proxy) H method, here is the Invoke method related to the place of the proxy.

Java-proxy is when to call Invocationhandler's Invoke method