Java dynamic Proxy implementation proxy and Invocationhandler

Concept:

Static proxy: The source code is generated automatically by the programmer or a specific tool, and then compiled. Before the program runs, the. class file for the proxy classes already exists.
Dynamic Agent: When the program is running, it is created dynamically using the reflection mechanism.

The dynamic proxy of the JDK is very simple to use, when it has a limitation that objects that use dynamic proxies must implement one or more interfaces. What if you want to delegate an inherited class that does not implement an interface ? Now we can use the Cglib package.

JDK Dynamic Proxy implementation

import java.lang.reflect.constructor;import java.lang.reflect.invocationhandler;import  java.lang.reflect.invocationtargetexception;import java.lang.reflect.method;import  Java.lang.reflect.proxy;import java.util.arraylist;import java.util.collection;public class  proxytest {    static stringbuilder sbuilder=new stringbuilder () ;     public static void main (String[] args)  throws  nosuchmethodexception, securityexception, instantiationexception, illegalaccessexception,  illegalargumentexception, invocationtargetexception {                 //proxy class byte code class clazzproxy1=     Proxy.getproxyclass (Collection.class.getClassLoader (),  collection.class);//proxy class construction method list, There is no parameterless construction method System.out.println (".... begin constructors list.... ");     constructor[] constructors= clazzproxy1.getconstructors (;);      for (constructor constructor:constructors) {          stringbuilder sbuilder=new stringbuilder ();         sbuilder.append (Constructor.getname ()). Append ("(");         class[] clazzparams =constructor.getparametertypes ();             for (Class clazzparam:clazzparams) {                          sbuilder.append (Clazzparam.getname ()). Append (",");                     }             &nbSp;   if (clazzparams.length!=0) {                         sbuilder.deletecharat ( Sbuilder.length ()-1);        }         sbuilder.append (")");         system.out.println (  Sbuilder.tostring ());      }        //proxy class method list     system.out.println ("..... begin methods list ..............        method[] methods= clazzproxy1.getmethods ();      for (method method:methods) {          Stringbuilder sbuilder=new stringbuilder ();         Sbuilder.append (Method.getname ()). Append ("(");         class[] clazzparams =method.getparametertypes ();             for (Class clazzparam:clazzparams) {                         sbuilder.append (Clazzparam.getname ()). Append (",");                     }                 if (clazzparams.length!=0) {                          sbuilder.deletecharat (Sbuilder.length ()-1);         }        sbuilder.append (")");       &nbSp; system.out.println ( sbuilder.tostring ());     }           //creates an instance of the proxy class through bytecode, and cannot be passed into the invocationhandler    using newinstance ().   system.out.println ("..... begin create instance object ..............            constructor constructor= Clazzproxy1.getconstructor (Invocationhandler.class);             Collection proxy1=     (Collection)  constructor.newinstance (new  invocationhandler () {             @Override             public object invoke (Object  proxy, method method, object[] args)                      throws Throwable {                                  return null;             }                     });             system.out.println (Proxy1);     proxy1.clear ();//method with no return value succeeded     // One step create proxy class instance     collection proxy2= (Collection)  proxy.newproxyinstance ( Collection.class.getClassLoader (), New class[]{collection.class}, new invocationhandler () {         ArrayList target=new ArrayList<> ();//proxy object, target object          @Override         public object invoke (Object  Proxy, method method, object[] args)                  throws Throwable {                          Long begintime=system.currenttimemillis ();             object retval=method.invoke (Target, args);             long endtime=system.currenttimemillis ();             system.out.println (Method.getname () + " running time is   " + (endtime-begintime));             Return retval;        }            });         proxy2.add ("Lhm");     proxy2.add ("zxx");     proxy2.add ("BxD");     system.out.println (Proxy2.size ());     system.out.println (Proxy2.getclass (). GetName ());    }                     }

This article is from the "bit accumulation" blog, please be sure to keep this source http://tianxingzhe.blog.51cto.com/3390077/1719600

Java dynamic Proxy implementation proxy and Invocationhandler