monitorfilereadsdirectly.aj

designpatterns for aop

package designpatterns.decorator.aspectjdirect;

import java.io.InputStream;
import java.util.Map;
import java.util.WeakHashMap;

import javax.swing.JComponent;


public aspect MonitorFileReadsDirectly {
	private Map perStreamMonitor = new WeakHashMap();
	
	pointcut singleRead(JComponent component, InputStream is):
		call(public int InputStream+.read()) && target(is)
		&& fromAComponent(component);
	
	pointcut arrayRead(JComponent component, InputStream is) :
		call(public int InputStream+.read(..)) && target(is)
		&& fromAComponent(component);
	
	pointcut fromAComponent(JComponent component) : 
		cflow(execution(* javax.swing.JComponent+.*(..))
			&& this(component));
	
	after(JComponent component, InputStream is) returning :
		singleRead(component, is)
	{
		updateMonitor(component, is, 1);
	}
	
	after(JComponent component, InputStream is) returning (int bytesRead) :
		arrayRead(component, is)
	{
//		updateMonitor(component, is, bytesRead);
	}
	
	before(InputStream is): 
		call(public void InputStream+.close())
		&& target(is)
	{
		System.out.println("Discarding monitor.");
		perStreamMonitor.remove(is);
	}
	
	private void updateMonitor(JComponent component, InputStream is,
				   int amount){
		IncrementMonitor monitor = 
			(IncrementMonitor)perStreamMonitor.get(is);
		if(monitor == null){
			monitor = initMonitor(is, component);
		}
		monitor.increment(amount);
	}
	
	private IncrementMonitor initMonitor(InputStream is,
					       JComponent component){
		try {
			int size = is.available();
			IncrementMonitor monitor = 
				new IncrementMonitor(component, size);
			perStreamMonitor.put(is, monitor);
			return monitor;
		} catch (Exception e) {
			throw new RuntimeException(e);
		}
	}
	
}