packetrenderapplet.java

本程序是用java编写的一些关于arq协议实现的小程序

import java.awt.*;
import java.applet.*;
import java.util.*;
import java.awt.event.*;
import java.awt.List;
import javax.swing.Timer;

class PacketWindow {

    protected PacketRenderApplet applet;
    protected int start_sqn;
    protected int window_size;
    protected int window[];
    public int finished = 0;

    public PacketWindow(PacketRenderApplet applet, int start_sqn, int window_size) {
        this.applet = applet;
        this.start_sqn = start_sqn;
        this.window_size = window_size;
        this.window = new int[applet.numPackets]; 
        for (int i=0; i<applet.numPackets; ++i) 
            this.window[i] = 0;
    }

    public void receivePacket (Packet packet) {}

}

class PacketTimer extends Timer {

    public int packet_no;

    public PacketTimer (int delay, ActionListener actionListener, int packet_no) {
        super (delay, actionListener);
        this.packet_no = packet_no;
    }

}

class TimeoutHandler implements ActionListener {

    private SenderWindow swin;

    public PacketTimer timer;
    
    public void actionPerformed (ActionEvent e) {
        synchronized (swin.applet.paintLock) {
                Thread thread = new SimplePacketThread(swin.applet, timer.packet_no);
                swin.applet.addThread(thread);
                thread.start();
                swin.applet.fillPacketNumbersList(swin.applet.packetType.getSelectedItem());
        }
    }

    public void setTimer (PacketTimer timer) {
        this.timer = timer;
    }

    public TimeoutHandler (SenderWindow swin) {
        this.swin = swin;
    }
}

class SenderWindow extends PacketWindow {

    Vector timers = new Vector();
    private int timeout=25000;

    public SenderWindow (PacketRenderApplet applet, int start_sqn, int window_size) {
        super(applet, start_sqn, window_size);
    }

    public void drawWindow (Color color) {
           synchronized (applet.paintLock) {
               applet.gBuffer.setColor(color);
               applet.gBuffer.draw3DRect(applet.left + start_sqn * applet.gap - 5, applet.top - 5, applet.gap * window_size, applet.packetSize + 10, true);
               applet.repaint();
           }
    }

    synchronized public void addTimer (int packet_no) {
        TimeoutHandler timeoutHandler = new TimeoutHandler (this);
        PacketTimer timer = new PacketTimer (timeout, timeoutHandler, packet_no);
        timeoutHandler.setTimer(timer);
        timers.addElement(timer); 
        timer.start();
    }

    synchronized public void resumeTimer (int packet_no) {
        Enumeration e = timers.elements();

        while (e.hasMoreElements()) {
              PacketTimer timer = (PacketTimer) e.nextElement();
              if (timer.packet_no == packet_no) {
                 timer.start();
              }
        }
    }

    synchronized public void stopTimer (int packet_no) {
        Enumeration e = timers.elements();

        while (e.hasMoreElements()) {
              PacketTimer timer = (PacketTimer) e.nextElement();
              if (timer.packet_no == packet_no) {
                 timer.stop();
              }
        }
    }

    synchronized public void removeTimer (int packet_no) {
        Enumeration e = timers.elements();

        stopTimer(packet_no);
        while (e.hasMoreElements()) {
              PacketTimer timer = (PacketTimer) e.nextElement();
              if (timer.packet_no == packet_no) {
                 timers.removeElement(timer);
              }
        }
    }

    synchronized public void startAllTimers () {
        Enumeration e = timers.elements();

        while (e.hasMoreElements()) {
              PacketTimer timer = (PacketTimer) e.nextElement();
              timer.start();
        }
    }

    synchronized public void stopAllTimers () {
        Enumeration e = timers.elements();

        while (e.hasMoreElements()) {
              PacketTimer timer = (PacketTimer) e.nextElement();
              timer.stop();
        }
    }

    synchronized public void removeAllTimers () {
        stopAllTimers();
        timers.removeAllElements();
    }

    public void receivePacket (Packet packet) {

           synchronized (applet.paintLock) {
                 applet.drawStatus("Ack " + packet.packet_no + " received", Color.green);
                 applet.repaint();
           }

           if ((packet.packet_no >= start_sqn) && (packet.packet_no < start_sqn + window_size)) {
              removeTimer(packet.packet_no);
              window[packet.packet_no] = 1;
              int i = start_sqn;
              int index;
              int j=0;
              while ((i < applet.numPackets)&&(window[i] == 1)) {
                  index = i + window_size;
                  if (index < applet.numPackets) {
                     synchronized (applet.paintLock) {
                        Thread thread = new SimplePacketThread(applet, index, 400*j);
                        applet.addThread(thread);
                        thread.start();
                        addTimer(index);
                     }
                     j++;
                  }
                  i++;
              }
              drawWindow (Color.black); 
              start_sqn = i;
              drawWindow (Color.gray);
           }

           if (start_sqn == applet.numPackets) {
               drawWindow(Color.black);
               finished = 1;
               synchronized (applet.paintLock) {
                  applet.endButtonState();
               }
           }
    }

}

class ReceiverWindow extends PacketWindow {

    public ReceiverWindow (PacketRenderApplet applet, int start_sqn, int window_size) {
        super(applet, start_sqn, window_size);
    }

    public void drawWindow (Color color) {
           synchronized (applet.paintLock) {
               applet.gBuffer.setColor(color);
               applet.gBuffer.draw3DRect(applet.left + start_sqn * applet.gap - 5, applet.bottom - 5, applet.gap * window_size, applet.packetSize + 10, true);
               applet.repaint();
           }
    }

    public void receivePacket (Packet packet) {
           synchronized (applet.paintLock) {
                 applet.drawStatus("Packet " + packet.packet_no + " received", Color.green);
                 applet.repaint();
           }
           if (packet.packet_no >= start_sqn + window_size) return;
           if ((packet.packet_no >= start_sqn)) {
              window[packet.packet_no] = 1;
              int i = start_sqn;
              int index;
              while ((i < applet.numPackets)&&(window[i] == 1)) {
                  i++;
              }
              drawWindow (Color.black); 
              start_sqn = i;
              drawWindow (Color.gray); 
           }
           synchronized (applet.paintLock) {
               Thread thread = new SimpleAckThread(applet, packet.packet_no);
               applet.addThread(thread);
               thread.start();
           }

           if (start_sqn == applet.numPackets) {
               drawWindow(Color.black);
               finished = 1;
           }
    }

}


class Packet {

    public int packet_no;
    public String type;
    public Color color;
    public int packetSize;

    public Packet(int packet_no, String type) {
        this.packet_no = packet_no;
        this.type = type;
        if (type.equals("PACKET")) {
           this.color = Color.red;
        }
        else if (type.equals("ACK")) {
           this.color = Color.yellow;
        }
        packetSize = 15;
    }

}

// This Thread draws a packet starting from location x0, y0 to location x1, y1
// You can also specify the speed with which packet moves and the color of the packet 

class PacketDrawingThread extends Thread {
    protected PacketRenderApplet applet;
    private int x;
    private int y0;
    private int y1;
    private int oldy0;

    private Object lock = new Object();
    private int suspend = 0;
    private int disappear = 0;

    public Packet packet;


    public PacketDrawingThread(PacketRenderApplet applet, Packet packet, int x, int y0, int y1) {
        this.applet = applet;
        this.x = x;
        this.y0 = y0;
        this.y1 = y1;
        this.oldy0 = y0;
        this.packet = packet;
    }

    public void suspendThread() {
        suspend = 1;
    }

    public void resumeThread() {
        suspend = 0;
        resume();
    }

    public void run() 
    {
        int yinterval; 
        int distanceRemaining;
        int temp;

        synchronized (applet.paintLock) {
               if (packet.type == "PACKET") {
                  applet.drawStatus("Packet " + packet.packet_no + " sent", Color.green);
               }
               else if (packet.type == "ACK") {
                  applet.drawStatus("Ack " + packet.packet_no + " sent", Color.green);
               }
        
               applet.gBuffer.setColor(packet.color);
               applet.gBuffer.fillRect(x, y0, packet.packetSize, packet.packetSize);
               applet.gBuffer.setFont(new Font(null, Font.BOLD, 14));
               applet.gBuffer.setColor(Color.black);
               applet.gBuffer.drawString(String.valueOf(packet.packet_no), x+packet.packetSize/4, y0+packet.packetSize - 3);
               applet.repaint();
        }

        while (y1 != y0) {

            if (suspend == 1) suspend();
           
            try {this.sleep(30);} 
            catch(Exception e) {}

            yinterval = applet.speed;

            if (y1 >= y0) {
                distanceRemaining = y1 - y0;
                if (distanceRemaining > yinterval) 
                    y0 += yinterval;
                else 
                    y0 = y1;
            }
            else {
                distanceRemaining = y0 - y1;
                if (distanceRemaining > yinterval) 
                    y0 -= yinterval;
                else 
                    y0 = y1;
            }

            synchronized (applet.paintLock) {
               applet.gBuffer.setColor(Color.black);
               applet.gBuffer.fillRect(x, oldy0, packet.packetSize, packet.packetSize);

               applet.gBuffer.setColor(packet.color);
               applet.gBuffer.fillRect(x, y0, packet.packetSize, packet.packetSize);
               applet.gBuffer.setFont(new Font(null, Font.BOLD, 14));
               applet.gBuffer.setColor(Color.black);
               applet.gBuffer.drawString(String.valueOf(packet.packet_no), x+packet.packetSize/4, y0+packet.packetSize - 3);
               oldy0 = y0;
               applet.repaint();
            }
        }
        synchronized (applet.paintLock) {
           applet.callback_function (this);
        }
    }

    public void disappear() {
                this.stop();
                synchronized (applet.paintLock) {
                      applet.gBuffer.setColor(Color.black);
                      applet.gBuffer.fillRect(x, oldy0, packet.packetSize, packet.packetSize);
                      applet.repaint();
                }
    }
}

class SimplePacketThread extends PacketDrawingThread {
    private int sleepDuration = 0;