网络编程思考与实践

编写了一个TCP服务程序，将telnet客户端发送过来的字符串反向，然后发送给客户端。用户可以使用默认端口8888进行通信，也可以输入自己的端口，自己输入的端口会被保存在txt文件中，如果下次运行服务器的话就会调用txt文件中的端口号。本程序可以实现多线程通信。

具体实现代码如下所示：

package tcptest;import java.net.*;import java.io.*;public class TCPServer {public static void main(String[] args) {// TODO Auto-generated method stubServerSocket ss = null;File f = new File("port.txt");if(f.exists()) {try {//FileInputStream fi = new FileInputStream(f);FileReader fr = new FileReader(f);BufferedReader bf = new BufferedReader(fr);String str = bf.readLine();ss = new ServerSocket(Integer.parseInt(str));} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}else {try {if(args.length==0) {ss = new ServerSocket(8888);System.out.println("用默认的啦！");}else {ss = new ServerSocket(Integer.parseInt(args[0]));System.out.println("用自己的啦！");FileOutputStream os = new FileOutputStream("port.txt");os.write(args[0].getBytes());os.close();}} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();} }System.out.println(ss.getLocalPort());while(true) {try {Socket s = ss.accept();new Thread(new Servicer(s)).start();} catch (IOException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}

 

package tcptest;import java.io.*;import java.net.*;public class Servicer implements Runnable {Socket s = null;public Servicer(Socket s) {this.s = s;}public void run() {try {InputStream is = s.getInputStream();OutputStream os = s.getOutputStream();BufferedReader bf = new BufferedReader(new InputStreamReader(is));PrintWriter pw = new PrintWriter(os, true);while(true) {String str = bf.readLine();String str2 = new StringBuffer(str).reverse().toString();if(str.equals("bye")) {break;}//System.out.println(str2);pw.println(str+"--->"+ str2 );/*如果改成这样为什么就接收不到数据了呢？pw.print(str+"--->"+ str2 + "/r/n");如果这样改的话应该再调用一次pw.flush()方法，因为printWriter的println方法不支持自动刷新功能。*///pw.println();//System.out.println("服务器发了");}bf.close();os.close();s.close();} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}}