testdatagramsocket.java

本书是一本为Java学习者在基础内容学习结束后进行课程设计时提供参考的指导书

package apibook.c5.s1;

import java.net.*;
import java.io.*;

//测试DatagramSocket类
class EchoServer extends Thread {
    private DatagramSocket sock = null;
    EchoServer(int port) {
        try {//建立数据包socket
            sock = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }
    public void run() {
        if (sock == null)
            return;//如果socket没有建立，则返回

        byte[] inbuf = new byte[1024];//缓冲区
        DatagramPacket request = new DatagramPacket(inbuf, inbuf.length);
        try {
            while (true) {//循环收发
                sock.receive(request);//接收
                sock.send(request);//发送
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}
public class TestDatagramSocket {
  static int echo_port = 1234;

  public TestDatagramSocket() {
  }

public static void echo(String msg, DatagramSocket client) {
  byte[] inbuf = new byte[1024];  // 缓冲区
  byte[] outbuf = msg.getBytes(); //发送的内容

  try {
      DatagramPacket request = new DatagramPacket(outbuf, outbuf.length);
      DatagramPacket reply = new DatagramPacket(inbuf, inbuf.length);
      client.send(request);//发送
      client.receive(reply);//接收
      client.close();//关闭
      System.out.println(new String(reply.getData()));//输出接收的结果
  } catch (SocketException e) {
      e.printStackTrace();
  } catch (IOException e) {
      e.printStackTrace();
  }
}

  public static void main(String[] args) {
    String msg= "";
    if (args.length != 1) {
        msg = "test for DatagarmSocket";
    }
    else
      msg = args[0];

    //开始
    EchoServer srv = new EchoServer(echo_port);
    srv.setDaemon(true);
    srv.start();

    try {
        InetAddress dst = InetAddress.getLocalHost();
        DatagramSocket dest = new DatagramSocket();
        dest.connect(dst, echo_port);

        System.out.println("remote addr: " + dest.getInetAddress());
        System.out.println("remote port: " + dest.getPort());

        echo(msg, dest);

        dest.disconnect();

        System.out.println("disconnected addr: " + dest.getInetAddress());
        System.out.println("disconnected port: " + dest.getPort());

    } catch (UnknownHostException e) {
        System.err.println("Host not found: " + e);
    } catch (SocketException e) {
        e.printStackTrace();
    }
  }


}