StoppableInputStream.java

package org.freehep.application;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InterruptedIOException;
import java.net.URL;
import java.net.URLConnection;

import javax.swing.BoundedRangeModel;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.event.EventListenerList;

/**
 * An input stream which also implements Stoppable. Useful when downloading
 * files in order to provide the user with feedback on progress.
 * @author Tony Johnson (tonyj@slac.stanford.edu)
 * @version $Id: StoppableInputStream.java 8584 2006-08-10 23:06:37Z duns $
 */
public class StoppableInputStream extends FilterInputStream implements Stoppable, BoundedRangeModel
{
   private boolean stop = false;
   private int pos = 0;
   private int max;
   private int markPos;
   private EventListenerList listenerList = new EventListenerList();
   private ChangeEvent event = new ChangeEvent(this);
   
   public StoppableInputStream(URL url) throws IOException
   {
      this(url.openConnection());
   }
   private StoppableInputStream(URLConnection connection) throws IOException
   {
      super(connection.getInputStream());
      max = connection.getContentLength();
   }
   public StoppableInputStream(InputStream in, int length)
   {
      super(in);
      max = length;
   }
   public BoundedRangeModel getModel()
   {
      return this;
   }
   public void stop()
   {
      stop = true;
   }
   public int read(byte[] b) throws IOException
   {
      if (stop) throw new InterruptedIOException("IO aborted by user");
      int l = super.read(b);
      pos += l;
      firePositionChanged();
      return l;
   }
   public int read() throws IOException
   {
      if (stop) throw new InterruptedIOException("IO aborted by user");
      int value = super.read();
      pos++;
      firePositionChanged();
      return value;
   }
   public int read(byte[] b, int off, int len) throws IOException
   {
      if (stop) throw new InterruptedIOException("IO aborted by user");
      int l = super.read(b,off,len);
      pos += l;
      firePositionChanged();
      return l;
   }
   public long skip(long n) throws IOException
   {
      if (stop) throw new InterruptedIOException("IO aborted by user");
      long l = super.skip(n);
      pos += (int) l;
      firePositionChanged();
      return l;     
   }
   public void reset() throws IOException
   {
      if (stop) throw new InterruptedIOException("IO aborted by user");
      super.reset();
      pos = markPos;
      firePositionChanged();
   }
   public void mark(int readlimit)
   {
      super.mark(readlimit);
      markPos = pos;
   }
   public void addChangeListener(ChangeListener x)
   {
      listenerList.add(ChangeListener.class,x);
   }
   public void removeChangeListener(ChangeListener x)
   {
      listenerList.remove(ChangeListener.class,x);
   }
   private void firePositionChanged()
   {
      ChangeListener[] list = (ChangeListener[]) listenerList.getListeners(ChangeListener.class);
      for (int i=0; i<list.length; i++)
      {
         list[i].stateChanged(event);
      }
   }
   public int getExtent()
   {
      return 0;
   }
   public int getMaximum()
   {
      return max;
   }
   public int getMinimum()
   {
      return 0;
   }
   public int getValue()
   {
      return pos;
   }
   public boolean getValueIsAdjusting()
   {
      return false;
   }
   public void setExtent(int newExtent)
   {
   }
   public void setMaximum(int newMaximum)
   {
   }
   public void setMinimum(int newMinimum)
   {
   }
   public void setRangeProperties(int value, int extent, int min, int max, boolean adjusting)
   {
   }
   public void setValue(int newValue)
   {
   }
   public void setValueIsAdjusting(boolean b)
   {
   }
}