gbn.rar_GBN 演示_arq java

// Java Applet Demonstration of Go-Back-N Protocol. // Coded by gongbo ID: 01091251 // Course No. EEE-459/591. Spring 2012 import java.applet.Applet; import java.awt.*; import java.awt.event.ActionListener; import java.awt.event.ActionEvent; public class gbn 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; final int h_offset_def=100; final int v_offset_def=50; final int v_clearance_def=300; final int total_packet_def=20; final int time_out_sec_def= 30; 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 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; 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; base= 0;// Defining base nextseq= 0;// Defining Next sequence number. fps= 5;// Defining default Frame per Second. sender= new packet[total_packet]; statusMsg= "Ready to run. Press 'Send New' button to start."; strCurrentValues= "Window Base= "+ 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)) sender[i].packet_pos+=5; // Move packet else if (sender[i].packet_ack) // If it is moving 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; statusMsg= "Packet "+i+" received. No acknowledge sent."; if (i==selected) { selected= -1; kill.setEnabled(false); } } } 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; if (i==selected) { selected= -1; kill.setEnabled(false); } timerThread= null; //resetting timer thread if (i+window_len<total_packet) base= i+1; if (nextseq < base+window_len) send.setEnabled(true); if (base != nextseq) { statusMsg += " Timer restarted."; timerThread= new Thread(this); timerSleep= true; timerThread.start(); } else statusMsg += " Timer stopped."; } strCurrentValues= "Window Base= "+ 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); } catch (InterruptedException e) { System.out.println ("Timer interrupted."); } } else { for (int n=base; n<base+window_len; n++) if (sender[n] != null) if (!sender[n].acknowledged) { 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 < base+window_len) // Send button is pressed { sender[nextseq]= new packet(true,pack_height+5); statusMsg= "Packet "+ nextseq +" sent."; if (base== nextseq) { // i.e. the window is empty and a new data is getting in st