sr.java

计算机网络的SR演示实验,有需要的可以看看

package com.jjh.net;
// Java Applet Demonstration of Go-Back-N Protocol.
// Coded by Shamiul Azom. ASU ID: 993456298
// as project assigned by Prof. Martin Reisslein, Arizona StateUniversity
// Course No. EEE-459/591. Spring 2001
import java.applet.Applet;
import java.awt.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.util.*;

public class SR extends Applet implements ActionListener, Runnable {
	final int window_len_def = 5; // Default values of parameters

	final int pack_width_def = 10;

	final int pack_height_def = 30;
     
	//水平方向偏移
	final int h_offset_def = 150;

	final int v_offset_def = 50;
    //两行相距
	final int v_clearance_def = 300;

	final int total_packet_def = 20;

	final int time_out_sec_def = 15;

	final Color unack_color = Color.red; // Default colors of different packets

	final Color ack_color = Color.yellow;

	final Color sel_color = Color.green;

	final Color roam_pack_color = Color.red;

	final Color roam_ack_color = Color.yellow;

	final Color dest_color = Color.blue;

	int snd_base, nextseq, fps, selected = -1;

	boolean timerFlag, timerSleep;

	Button send, stop, fast, slow, kill, reset;

	Thread gbnThread, timerThread;

	Dimension offDimension; // flashing eliminator: double buffering

	Image offImage;

	Graphics offGraphics;

	String statusMsg, strCurrentValues;

	packet sender[];

	// Declaring properties
	int window_len, pack_width, pack_height, h_offset, v_offset, v_clearance,
			total_packet, time_out_sec;
	
	long  currentTime = 0;
	
	Set<Integer>  snd_buffer = new TreeSet<Integer>();
	
	
	Set<Integer>  rcv_buffer = new TreeSet<Integer>();
	
	int    rcv_base = 0;

	public void init() {
		String strWinLen, strPackWd, strPackHt, strHrOff, strVtOff, strVtClr, strTotPack, strTimeout;
		strWinLen = getParameter("window_length"); // Start collecting
		// parameters
		strPackWd = getParameter("packet_width");
		strPackHt = getParameter("packet_height");

		strHrOff = getParameter("horizontal_offset");
		strVtOff = getParameter("vertical_offset");
		strVtClr = getParameter("vertical_clearance");
		strTotPack = getParameter("total_packets");
		strTimeout = getParameter("timer_time_out");
		// Get the values of the parameters into properties.
		try {
			if (strWinLen != null)
				window_len = Integer.parseInt(strWinLen);
			if (strPackWd != null)
				pack_width = Integer.parseInt(strPackWd);
			if (strPackHt != null)
				pack_height = Integer.parseInt(strPackHt);
			if (strHrOff != null)
				h_offset = Integer.parseInt(strHrOff);
			if (strVtOff != null)
				v_offset = Integer.parseInt(strVtOff);
			if (strVtClr != null)
				v_clearance = Integer.parseInt(strVtClr);
			if (strTotPack != null)
				total_packet = Integer.parseInt(strTotPack);
			if (strTimeout != null)
				time_out_sec = Integer.parseInt(strTimeout);
		} catch (Exception e) {
		}
		// If parameter is not found, use default values.
		window_len = (window_len > 0) ? window_len : window_len_def;
		pack_width = (pack_width > 0) ? pack_width : pack_width_def;
		pack_height = (pack_height > 0) ? pack_height : pack_height_def;
		h_offset = (h_offset > 0) ? h_offset : h_offset_def;
		v_offset = (v_offset > 0) ? v_offset : v_offset_def;
		v_clearance = (v_clearance > 0) ? v_clearance : v_clearance_def;
		total_packet = (total_packet > 0) ? total_packet : total_packet_def;
		time_out_sec = (time_out_sec > 0) ? time_out_sec : time_out_sec_def;
		snd_base = 0; // Defining snd_base
		nextseq = 0; // Defining Next sequence number.
		fps = 10; // Defining default Frame per Second.
		sender = new packet[total_packet];
		statusMsg = "Ready to run. Press 'Send New' button to start.";
		strCurrentValues = "Window Base = " + snd_base + ". Next Sequence No. = "
				+ nextseq;
		// Defining the buttons
		send = new Button("Send New");
		send.setActionCommand("rdt");
		send.addActionListener(this);
		stop = new Button("Stop Animation");
		stop.setActionCommand("stopanim");
		stop.addActionListener(this);
		fast = new Button("Faster");
		fast.setActionCommand("fast");
		fast.addActionListener(this);
		slow = new Button("Slower");
		slow.setActionCommand("slow");
		slow.addActionListener(this);

		kill = new Button("Kill Packet");
		kill.setActionCommand("kl");
		kill.addActionListener(this);
		kill.setEnabled(false);
		reset = new Button("Reset");
		reset.setActionCommand("rst");
		reset.addActionListener(this);
		// Adding the buttons
		add(send);
		add(stop);
		add(fast);
		add(slow);
		add(kill);
		add(reset);
		
	}

	public void start() {
		if (gbnThread == null) // Creating main thread and start it
			gbnThread = new Thread(this);
		gbnThread.start();
	}

	public void run() {
		Thread currenthread = Thread.currentThread();
		while (currenthread == gbnThread)
			// While the animation is running
			if (onTheWay(sender)) // Checks if any of the packets are
			// travelling
			{
				for (int i = 0; i < total_packet; i++)
					if (sender[i] != null)
						if (sender[i].on_way) // If packet is roaming
							
							
							if (sender[i].packet_pos < (v_clearance - pack_height)) //在从上到下路上
								sender[i].packet_pos += 5; // Move packet
				
							else if (sender[i].packet_ack) // If it is moving //到达下端
							// to destination
							{ 
							
								sender[i].reached_dest = true;
								
								
							//	if (check_upto_n(i)) // Send acknowledgement
								// if all preceeding
								//{ // packets are received.
									sender[i].packet_pos = pack_height + 5;
									sender[i].packet_ack = false;
									statusMsg = "Packet " + i
											+ " received. Acknowledge sent.";
								//} else {
									//sender[i].on_way = false;
									if( i>=rcv_base && i <= rcv_base+window_len-1){
										if( i == rcv_base ){
											
											int[] seq = this.getRcvSequence(i);
											if (  rcv_base+seq.length+window_len>=total_packet){
												  rcv_base = total_packet-window_len;
											}
											else
												rcv_base+=seq.length;
										
											//System.out.println(rcv_base);
											this.removeRcvSequence(seq);
											//System.out.println(seq[0]);
										}
										else{
											rcv_buffer.add(new Integer(i));
										}
									}
									else if( i>=rcv_base-window_len && i <= rcv_base-1 ){
										  //仍是要产生一个ACK
									}
									else{
										//忽略
									}
									//statusMsg = "Packet " + i
									//		+ " received. No acknowledge sent.";
									/*if (i == selected) {
										selected = -1;
										kill.setEnabled(false);

									}*/
								//}
								
								
								//确认到达上端
							} else if (!sender[i].packet_ack) // acknowledgement 
							{
								statusMsg = "Packet " + i
										+ " acknowledge received.";
								
								sender[i].on_way = false;  
								//for (int n = 0; n <= i; n++)
									//sender[n].acknowledged = true;
								//??上面一个循环可以用下面一句替代，可否
								//sender[i].acknowledged = true;
								if( i < snd_base || i>snd_base+window_len-1 ){
									//忽略
								}
								else{
									if( i == snd_base ){
										//System.out.println(i);
										int[] seq = this.getSndSequence(i);
										
										
										if ( snd_base+window_len >= total_packet ||  (snd_base+seq.length+window_len>=total_packet) ){
											  snd_base = total_packet-window_len;
											  sender[i].acknowledged = true;
										}
										else
											snd_base+=seq.length;
										this.removeSndSequence(seq);
										for (int n = 0; n <  snd_base; n++)
										  sender[n].acknowledged = true;
										
									}
									else{
										snd_buffer.add(new Integer(i));
										System.out.println(i);
										sender[i].acknowledged = true;
									}
								}
								
								if (i == selected) {
									//System.out.println("jinjunhang");
									//??为何要把select设为-1
									selected = -1;
									kill.setEnabled(false);
								}
								timerThread = null; // resetting timer thread
								
								if (nextseq < snd_base + window_len)
									send.setEnabled(true);
								if (snd_base != nextseq) {
									System.out.println("jinjunhang");
									statusMsg += " Timer restarted.";
									timerThread = new Thread(this);
									timerSleep = true;
									timerThread.start();
								} else
									statusMsg += " Timer stopped.";
							}
				strCurrentValues = "Window Base = " + snd_base
						+ ". Next Sequence No. = " + nextseq;
				repaint();
				try {
					Thread.sleep(1000 / fps);
				} catch (InterruptedException e) {
					System.out.println("Help");
				}
			} else
				gbnThread = null;
		while (currenthread == timerThread)
			if (timerSleep) {
				timerSleep = false;
				try {
					//Thread.sleep(time_out_sec * 1000);
					Thread.sleep( 1 * 100);
				} catch (InterruptedException e) {
					System.out.println("Timer interrupted.");
				}
			}

			else {
				
				for (int n = snd_base; n < snd_base + window_len; n++)
					if (sender[n] != null)
						if (!sender[n].acknowledged) {
							long now = System.currentTimeMillis();
							if( now - sender[n].snd_time >= time_out_sec * 1000){
							  sender[n].snd_time = now;
							  sender[n].on_way = true;
							  sender[n].packet_ack = true;
							  sender[n].packet_pos = pack_height + 5;
							}
							
						}
				timerSleep = true;
				if (gbnThread == null) {
					gbnThread = new Thread(this);
					gbnThread.start();
				}
				statusMsg = "Packets resent by timer. Timer restarted.";
			}
	}

	public void actionPerformed(ActionEvent e) {
		String cmd = e.getActionCommand();
		if (cmd == "rdt" && nextseq < snd_base + window_len) // Send button is pressed
		{
			//????pack_height + 5
			sender[nextseq] = new packet(true, pack_height + 5);
			statusMsg = "Packet " + nextseq + " sent.";
			if (snd_base == nextseq) { // i.e. the window is empty and a new data is getting in
				statusMsg += " Timer set for packet " + snd_base + ".";
				if (timerThread == null)
					timerThread = new Thread(this);
				timerSleep = true;
				timerThread.start();
			}
			repaint();
			nextseq++;
			if (nextseq == snd_base + window_len)
				send.setEnabled(false);
			start();
		} else if (cmd == "fast") // Faster button pressed
		{
			fps += 2;