我们知道，在Java中，常用的动态代理技术有JDK的动态代理和cglib动态代理，但是不管是哪种方式，代理对象都是在程序运行时，运用反射机制动态创建而成，而我们并不能直观的看到生成的代理对象对应的Java源代码。下面，我就提供一种方式，可以将通过动态代理创建的代理对象的字节码文件保存到磁盘，再通过反编译工具查看生成文件的内容，这样就可以加深我们对于代理对象的理解。
JDK的动态代理依靠接口实现，如果有些类并没有实现接口，则不能使用JDK代理，这就要使用cglib动态代理了，在此，我们以JDK的动态代理为例。
在JDK中提供了一个ProxyGenerator类，可以将代理对象的字节码得到，我们再通过一个输出流就可以将文件保存到磁盘了。
首先定义一个接口：
public class JdkProxyTest {
public static void main(String[] args) throws Exception {
final IUserDao target = new UserDaoImpl();
IUserDao proxy = (IUserDao) Proxy.newProxyInstance(target.getClass()
.getClassLoader(), target.getClass().getInterfaces(),
new InvocationHandler() {
public Object invoke(Object proxy, Method method,
Object[] args) throws Throwable {
System.out.println(method.getName());
return method.invoke(target, args);
}
});
byte[] proxyClass = ProxyGenerator.generateProxyClass(proxy.getClass()
.getSimpleName(), proxy.getClass().getInterfaces());
//将字节码文件保存到D盘，文件名为$Proxy0.class
FileOutputStream outputStream = new FileOutputStream(new File(
d:\\$Proxy0.class ));
outputStream.write(proxyClass);
outputStream.flush();
outputStream.close();
}
import cn.itcast.jdkproxy.IUserDao;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;
public final class $Proxy0 extends Proxy
implements IUserDao
{
private static Method m3;
private static Method m1;
private static Method m0;
private static Method m2;
public $Proxy0(InvocationHandler paramInvocationHandler)
throws
{
super(paramInvocationHandler);
}
public final void save()
throws
{
try
{
this.h.invoke(this, m3, null);
return;
}
catch (RuntimeException localRuntimeException)
{
throw localRuntimeException;
}
catch (Throwable localThrowable)
{
}
throw new UndeclaredThrowableException(localThrowable);
}
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);
}
叩丁狼Java培训实战教程之将代理对象保存到本地文件
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 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
{
m3 = Class.forName( cn.itcast.jdkproxy.IUserDao ).getMethod( save , new Class[0]);
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]);
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());
}
