udpclient.java

《Java核心技术应用开发》电子工业出版社书籍源代码

/*
 * UDPClient.java
 *
 * Created on 2002年9月3日, 下午2:56
 */

package sample;
import java.io.*;
import java.net.*; 

public class UDPClient { 
            
   public void go() throws IOException, UnknownHostException { 
        DatagramSocket datagramSocket; 
        DatagramPacket outDataPacket; // Datagram packet to the server 
        DatagramPacket inDataPacket; // Datagram packet from the server 
        InetAddress serverAddress; // Server host address 
        byte[] msg = new byte[100]; // Buffer space. 
        String receivedMsg; // Received message in String form. 
  
        // Allocate a socket by which messages are sent and received. 
        datagramSocket = new DatagramSocket(); 
        System.out.println("!!!!!!at UDPClient,datagramSocket is: " + datagramSocket.getPort() + "local port is: " +datagramSocket.getLocalPort()); 
  
        // Server is running on this same machine for this example. 
        // This method can throw an UnknownHostException. 
        serverAddress = InetAddress.getLocalHost(); 
  
        // Set up a datagram request to be sent to the server. 
        // Send to port 8000. 
        outDataPacket = new DatagramPacket(msg, 1, serverAddress, 8000); 
  
        // Make the request to the server. 
        datagramSocket.send(outDataPacket); 
  
        // Set up a datagram packet to receive server's response. 
        inDataPacket = new DatagramPacket(msg, msg.length); 
  
        // Receive the time data from the server 
        datagramSocket.receive(inDataPacket); 
  
        // Print the data received from the server 
        receivedMsg = new String 
            (inDataPacket.getData(), 0, inDataPacket.getLength()); 
        System.out.println(receivedMsg); 
  
        //close the socket 
        datagramSocket.close(); 
    } 
  
    public static void main(String args[]) { 
        UDPClient udpClient = new UDPClient(); 
        try { 
            udpClient.go(); 
        } catch (Exception e) { 
            System.out.println ("Exception occured with socket."); 
            System.out.println (e); 
            System.exit(1); 
        } 
    } 
}