Java動態代理

標籤：java   動態代理   

動態代理涉及到的5個類：1. 介面Interface  2.被代理類 3.動態代理處理類  4.測試類別  5.產生的代理類

整個過程就是：先調用Proxy.newProxyInstance()方法，傳入介面，class loader以及動態代理處理類（被代理類是處理類的一個屬性，作為參數傳入），這個方法產生介面的一個實作類別（代理類），這個代理類繼承自Proxy類，所以可以得到傳入到Proxy類的動態代理處理類，代理類還實現了介面的所有方法，每個方法體就是去調用動態代理處理類的invoke方法，把方法體裡被調用時傳來的參數再傳到invoke方法裡去，這樣就實現了動態代理~

1. 介面Interface

package proxy;public interface Interface {void doSomething();void somethingElse(String args);}

2.被代理類

package proxy;public class RealObject implements Interface {@Overridepublic void doSomething() {// TODO Auto-generated method stubSystem.out.println("realObject do something");}@Overridepublic void somethingElse(String args) {// TODO Auto-generated method stubSystem.out.println("realObject something else ,args:" + args);}}

3.動態代理處理類

package proxy;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;public class ProxyHandler implements InvocationHandler {private RealObject realObj;public ProxyHandler(RealObject realObj) {// TODO Auto-generated constructor stubthis.realObj = realObj;}@Overridepublic Object invoke(Object arg0, Method arg1, Object[] arg2)throws Throwable {// TODO Auto-generated method stubSystem.out.println("before proxy");arg1.invoke(realObj, arg2);System.out.println("after proxy");return null;}}

4.測試類別

package proxy;import java.lang.reflect.Proxy;public class ProxyTest {public static void main(String[] args) {RealObject realObj = new RealObject();Interface proxy = (Interface) Proxy.newProxyInstance(Interface.class.getClassLoader(),new Class[] { Interface.class }, new ProxyHandler(realObj));System.out.println(proxy.getClass());proxy.doSomething();proxy.somethingElse("dayna");////        byte[] proxyClassFile = ProxyGenerator.generateProxyClass(//                "DaynaProxy", new Class[] { Interface.class });}}

5.產生的代理類

import com.pactera.oscar.fwapp2.pqs.eb.view.Interface;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.lang.reflect.UndeclaredThrowableException;public final class DaynaProxy extends Proxy  implements Interface{  private static Method m1;  private static Method m0;  private static Method m3;  private static Method m4;  private static Method m2;  public DaynaProxy(InvocationHandler paramInvocationHandler)    throws   {    super(paramInvocationHandler);  }  public final boolean equals(Object paramObject)    throws   {    try    {      return ((Boolean)this.h.invoke(this, m1, new Object[] { paramObject })).booleanValue();    }    catch (RuntimeException localRuntimeException)    {      throw localRuntimeException;    }    catch (Throwable localThrowable)    {    }    throw new UndeclaredThrowableException(localThrowable);  }  public final int hashCode()    throws   {    try    {      return ((Integer)this.h.invoke(this, m0, null)).intValue();    }    catch (RuntimeException localRuntimeException)    {      throw localRuntimeException;    }    catch (Throwable localThrowable)    {    }    throw new UndeclaredThrowableException(localThrowable);  }  public final void doSomething()    throws   {    try    {      this.h.invoke(this, m3, null);      return;    }    catch (RuntimeException localRuntimeException)    {      throw localRuntimeException;    }    catch (Throwable localThrowable)    {    }    throw new UndeclaredThrowableException(localThrowable);  }  public final void somethingElse(String paramString)    throws   {    try    {      this.h.invoke(this, m4, new Object[] { paramString });      return;    }    catch (RuntimeException localRuntimeException)    {      throw localRuntimeException;    }    catch (Throwable localThrowable)    {    }    throw new UndeclaredThrowableException(localThrowable);  }  public final String toString()    throws   {    try    {      return (String)this.h.invoke(this, m2, null);    }    catch (RuntimeException localRuntimeException)    {      throw localRuntimeException;    }    catch (Throwable localThrowable)    {    }    throw new UndeclaredThrowableException(localThrowable);  }  static  {    try    {      m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[] { Class.forName("java.lang.Object") });      m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);      m3 = Class.forName("com.pactera.oscar.fwapp2.pqs.eb.view.Interface").getMethod("doSomething", new Class[0]);      m4 = Class.forName("com.pactera.oscar.fwapp2.pqs.eb.view.Interface").getMethod("somethingElse", new Class[] { Class.forName("java.lang.String") });      m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);      return;    }    catch (NoSuchMethodException localNoSuchMethodException)    {      throw new NoSuchMethodError(localNoSuchMethodException.getMessage());    }    catch (ClassNotFoundException localClassNotFoundException)    {    }    throw new NoClassDefFoundError(localClassNotFoundException.getMessage());  }}

Java動態代理