Java动态代理

动态代理涉及到的5个类：1. 接口Interface 2.被代理类 3.动态代理处理类 4.测试类 5.生成的代理类

整个过程就是：先调用Proxy.newProxyInstance()方法，传入接口，class loader以及动态代理处理类（被代理类是处理类的一个属性，作为参数传入），这个方法生成接口的一个实现类（代理类），这个代理类继承自Proxy类，所以可以得到传入到Proxy类的动态代理处理类，代理类还实现了接口的所有方法，每个方法体就是去调用动态代理处理类的invoke方法，把方法体里被调用时传来的参数再传到invoke方法里去，这样就实现了动态代理~

1. 接口Interface

package proxy;

public interface Interface {
void doSomething();

void somethingElse(String args);
}

2.被代理类

package proxy;

public class RealObject implements Interface {

@Override
public void doSomething() {
// TODO Auto-generated method stub
System.out.println("realObject do something");
}

@Override
public void somethingElse(String args) {
// TODO Auto-generated method stub
System.out.println("realObject something else ,args:" + args);
}

}

3.动态代理处理类

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 stub
this.realObj = realObj;
}

@Override
public Object invoke(Object arg0, Method arg1, Object[] arg2)
throws Throwable {
// TODO Auto-generated method stub
System.out.println("before proxy");
arg1.invoke(realObj, arg2);
System.out.println("after proxy");
return null;
}

}

4.测试类

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.生成的代理类

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());
}
}