Jdk-proxy sample

The proxy tool class provided by JDK from 1.3 to provide some means of executing an interface in an agent way is applied in the implementation of Spring AOP;

jdk:1.8 code example

1. Interfaces that need to be represented

Package com.test.reflect;

/** *
 @author hinsteny *
 @Describtion *
 @date 2016/12/2 *
 @copyright: 2016 All rights reserved.
 * * Public
interface Scholar {

    String local = "Chiba";

    String  searching (string theme);

    Default String infolocal () {return this
        . local;
    }

2. Implementation classes that need to be represented

Package com.test.reflect;

Import Org.slf4j.Logger;
Import org.slf4j.LoggerFactory;

Import Java.time.LocalDateTime;

/** *
 @author hinsteny *
 @Describtion *
 @date 2016/12/2 *
 @copyright: 2016 All rights reserved.
 * * Public
class Scholarimpl implements scholar {

    static final private Logger Logger = Loggerfactory.getlogger (Sc Holarimpl.class);

    public static String Printtime () {
        logger.info (????, Localdatetime.now (). toString ());
        return ' time ';

    @Override public
    string searching (String theme) {
        Logger.info (' scholar do search {} ', theme);
        Return "Success";
    }

3. Implementation of the Invocationhandler interface, where the agent execution, you can add custom business logic (such as logging, permission to intercept, statistics, etc.)

Package com.test.reflect.jdk;

Import Org.slf4j.Logger;
Import org.slf4j.LoggerFactory;

Import Java.lang.reflect.InvocationHandler;
Import Java.lang.reflect.Method;

/** *
 @author hinsteny *
 @Describtion *
 @date 2016/12/2 *
 @copyright: 2016 All rights reserved.
 * * Public
class MyHandler implements Invocationhandler {

    static final private Logger Logger = Loggerfactory.get Logger (myhandler.class);

    Private object = null;

    Public MyHandler (Object object) {
        This.object = object;
    }

    @Override Public
    Object Invoke (Object Proxy, Method method, object[] args) throws Throwable {
        Logger.info ("Do s Omething before method {} ", Method.getname ());
        Object ret = Method.invoke (this.object, args);
        Logger.info ("Do something after method {}", Method.getname ());

        return ret;
    }
}

4. Test cases for viewing agent effects, and generation of class files for proxy classes

Package com.test.reflect.jdk;
Import Com.test.reflect.Scholar;
Import Com.test.reflect.ScholarImpl;
Import Org.junit.Test;
Import Org.slf4j.Logger;
Import Org.slf4j.LoggerFactory;

Import Sun.misc.ProxyGenerator;
Import Java.io.FileOutputStream;
Import java.io.IOException;

Import Java.lang.reflect.Proxy;
 /** * @author Hinsteny * @Describtion * @date 2016/12/2 * @copyright: 2016 All rights reserved.

    * * public class Jdkproxytest {static final private Logger Logger = Loggerfactory.getlogger (Jdkproxytest.class);

        @Test public void Testproxy () {//Scholarimpl object (being proxy) Managerimpl = new Scholarimpl ();

        Business Agent class MyHandler Securityhandler = new MyHandler (MANAGERIMPL);
        Obtain an instance of the proxy class ($Proxy 0 extends proxy implements Manager). Scholar Managerproxy = (scholar) proxy.newproxyinstance (JDKProxyTest.class.getClassLoader (), Managerimpl.getclass ()

        . Getinterfaces (), Securityhandler); Logger.info ("Scholar Local is {}", MANAGERPROxy.
        local);
        Logger.info ("Scholar default method does and result is {}", managerproxy.infolocal ());
        String theme = "Knowledge";
        String result = managerproxy.searching (theme);
    Logger.info ("result was {}", result); @Test public void Testgetproxyclass_1 () {//required to add Java command execution parameters [-dsun.misc.proxygenerator.savegeneratedfil Es=true]//Then the generated dynamic proxy object will be named from [$Proxy #.class] (#从0开始依次加1递增) System.out.println in the subdirectory of the following directory (Com\sun\proxy) (
        System.getproperty ("User.dir"));
        Testproxy ();
    can go to the corresponding directory to see the generated dynamic class class files, decompile the dynamic class of Java code Logger.info ("Finish at here {}"); @Test public void Testgetproxyclass_2 () {//Get the byte code of the proxy class byte[] Classfile = Proxygenerator.generat
        Eproxyclass ("$Proxy One", ScholarImpl.class.getInterfaces ());
        Write file String path = "d://data/$Proxy 1.class";
        FileOutputStream out = null;
            try {out = new FileOutputStream (path); Out.wRite (Classfile);
        Out.flush ();
        catch (Exception e) {e.printstacktrace ();
            Finally {try {if (out!= null) out.close ();
            catch (IOException e) {e.printstacktrace (); }
        }
    }

}

5. decompile view generate dynamic class source code

Package com.sun.proxy;
Import com.test.reflect.*;

Import java.lang.reflect.*;
    Public final class $Proxy extends Proxy implements scholar {private static method M1;
    private static method m2;
    private static method M4;
    private static method M3;

    private static method M0;
    Public $Proxy (Final Invocationhandler Invocationhandler) {super (Invocationhandler); Public Final Boolean equals (Final Object o) {try {return (Boolean) Super.h.invoke (this, $Proxy
        20.M1, new object[] {o}); catch (Error |
        RuntimeException error) {throw;
        The catch (Throwable t) {throw new undeclaredthrowableexception (t); } Public final String toString () {try {return (String) Super.h.invoke (this, $Proxy 20.m2, n
        ULL); catch (Error |
        RuntimeException error) {throw; catch (Throwable t) {throw new UndEclaredthrowableexception (t); } Public final String infolocal () {try {return (String) Super.h.invoke (this, $Proxy 20.m4,
        NULL); catch (Error |
        RuntimeException error) {throw;
        The catch (Throwable t) {throw new undeclaredthrowableexception (t);  } public final string searching (final string s) {try {return (string) Super.h.invoke.
        $Proxy 20.m3, new object[] {s}); catch (Error |
        RuntimeException error) {throw;
        The catch (Throwable t) {throw new undeclaredthrowableexception (t);
        } public final int hashcode () {try {return (int) Super.h.invoke (this, $Proxy 20.m0, NULL); catch (Error |
        RuntimeException error) {throw;
        The catch (Throwable t) {throw new undeclaredthrowableexception (t);

  }
    }  static {try {$Proxy 20.m1 = Class.forName ("Java.lang.Object"). GetMethod ("Equals", Class.forName ("Ja
            Va.lang.Object "));
            $Proxy 20.m2 = Class.forName ("Java.lang.Object"). GetMethod ("ToString", (class<?>[)) new class[0]);
            $Proxy 20.m4 = Class.forName ("Com.test.reflect.Scholar"). GetMethod ("Infolocal", (class<?>[)) new class[0]); $Proxy 20.m3 = Class.forName ("Com.test.reflect.Scholar"). GetMethod ("Searching", Class.forName ("java.lang.String"))
            ;
        $Proxy 20.m0 = Class.forName ("Java.lang.Object"). GetMethod ("Hashcode", (class<?>[)) new class[0]);
        The catch (Nosuchmethodexception ex) {throw new Nosuchmethoderror (Ex.getmessage ());
        catch (ClassNotFoundException ex2) {throw new Noclassdeffounderror (Ex2.getmessage ());
 }
    }
}

Note: