GBN.rar_GBN_gbn Ja_gbn java _java GBN_java实现gbn

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 =