GBN 计算机网络原理 java实现

import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.io.OutputStreamWriter; import java.io.PrintWriter; import java.net.Socket; import java.net.UnknownHostException; import java.util.Date; import java.util.Random; public class GBNClient { Socket client; BufferedReader in; PrintWriter out; //时钟线程 public static Random rand = new Random(); int base,seqnum,N,array_len; String[] pkt = new String[100]; //延时5秒 long Time = 5000; boolean timeout; public GBNClient() { super(); try { client = new Socket("127.0.0.1", 4444); this.clock = new Clock(Time); //初始化 base = 0; seqnum = 0; array_len = 100; N = 10; //window宽10 timeout=false; //in，out与Server端通信 in = new BufferedReader(new InputStreamReader(client.getInputStream())); out = new PrintWriter(new OutputStreamWriter(client.getOutputStream())); SendPkt(); } catch (UnknownHostException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } public static void main(String[] args) { new GBNClient(); } void SendPkt() { String inStr; String[] ack; initPktArray(); try{ while( seqnum < N+base ){ System.out.println("send packet[" +seqnum+ "] packet["+seqnum+"] = "+ pkt[seqnum]); //通过概率模拟该包是否发出，这里发出去的概率为80% if(rand.nextInt(100) >= 80) { System.out.println("\nThe package[" + seqnum + "] didn't send out!"); seqnum++; } else { out.println(pkt[seqnum++]); out.flush(); inStr = in.readLine(); System.out.println(inStr); //如果收到的包序号不等于seqnum-1，则之前有包Server未能收到，重新发。 ack = inStr.split(":"); if((Integer.parseInt(ack[1])) == seqnum - 1){ base++; } } } out.println("end"); out.flush(); System.out.println(in.readLine()); }catch (IOException e) { e.printStackTrace(); }finally { try { client.close(); } catch (IOException e) { e.printStackTrace(); } } } /*public void refuse_data() { System.out.println("窗口数已满!"); System.out.println("拒绝发送数据!"); System.out.println("************************************"); }*/ void initPktArray() { for (int i = 0; i < array_len; i++) { // 初始化包 pkt[i] = (i + ":" + Integer.toString(rand.nextInt(100000))); } } class Clock implements Runnable { long time; long startTime; boolean flag = true; public Clock(long time) { this.time =time; } public void start_timer() { this.flag = true; Thread thread = new Thread(this); this.startTime = new Date().getTime(); thread.start(); } public synchronized void stop_timer() { this.flag = false; } public void timeout() { this.stop_timer(); seqnum = base; } @Override public void run() { // TODO Auto-generated method stub while(true) { if(flag) { long t = new Date().getTime() - this.startTime; if(t % 1000 == 0) { //labelTime.setText("time: " + t / 1000); } if(t > this.time) { this.timeout(); } } else break ; } } } }