这个附加的功能可以设计一个单独的OrderProxy类来实现，它与真实对象Order一样实现OrderIF接口。这样保证了OrderProxy对象提供给客户与真实对象Order一样的接口。如图3
Figure3: Order Class Hierarchy with the Counting Proxy
public class OrderProxy implements OrderIF {
private int counter = 0;
public Vector getAllOrders() {
Order order = new Order();
counter++;
long t1 = System.currentTimeMillis ();
Vector v = order.getAllOrders();
long t2 = System.currentTimeMillis();
long timeDiff = t2 ? t1;
String msg = "Iteration=" + counter + "::Time=" + timeDiff + "ms";
//log the message
FileUtil fileUtil = new FileUtil();
fileUtil.writeToFile("log.txt”,msg, true, true);
return v;
}
}
客户对象MainApp就想调用真实对象Order一样调用OrderProxy对象上的getAllOrders()方法，OrderProxy对象传递这个调用给真实对象Order,计算读取所有订单所花费的时间并使用FileUtil帮助类将其纪录的log日志文件中。在这个过程中， OrderProxy扮演者计数代理的角色。
public class MainApp {
public static void main(String[] args) {
OrderIF order = new OrderProxy();
Vector v = order.getAllOrders();
v = order.getAllOrders();
v = order.getAllOrders();
v = order.getAllOrders();
}
}
