UDP协议的网络编程

java网络编程之UDP实例

package Socket;

import java.net.DatagramPacket;
import java.net.InetAddress;

public class Dgram {

public static DatagramPacket toDatagram(String s, InetAddress destIA,
int destPort) {
byte[] buf = new byte[s.length() + 1];
s.getBytes(0, s.length(), buf, 0);
return new DatagramPacket(buf, buf.length, destIA, destPort);
}

public static St
4000
ring toString(DatagramPacket p) {
return new String(p.getData(), 0, p.getLength());
}
}

package Socket;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.SocketException;

public class ChatterServer {
static final int INPORT = 1712;
private byte[] buf = new byte[1000];
private DatagramPacket dp = new DatagramPacket(buf, buf.length);
private DatagramSocket socket;

public ChatterServer() {
try {
socket = new DatagramSocket(INPORT);// 创建一接收消息的对象，而不是每次接收消息都创建一个
System.out.println("Server started");
while (true) {
socket.receive(dp);
//接收到客户端的消息
String rcvd = Dgram.toString(dp) + ",from address:"
+ dp.getAddress() + ",port:" + dp.getPort();
System.out.println("From Client:"+rcvd);

String echoString = "From Server Echoed:" + rcvd;
DatagramPacket echo = Dgram.toDatagram(echoString,
dp.getAddress(), dp.getPort());
//将数据包发送给客户端
socket.send(echo);
}
} catch (SocketException e) {
System.err.println("Can't open socket");
System.exit(1);
} catch (IOException e) {
System.err.println("Communication error");
e.printStackTrace();
}
}

public static void main(String[] args) {
new ChatterServer();
}
}

package Socket;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;

public class ChatterClient extends Thread {

private DatagramSocket s;
private InetAddress hostAddress;
private byte[] buf = new byte[1000];
private DatagramPacket dp = new DatagramPacket(buf, buf.length);
private int id;

public ChatterClient(int identifier) {
id = identifier;
try {
s = new DatagramSocket();
hostAddress = InetAddress.getByName("localhost");

} catch (UnknownHostException e) {
System.err.println("Cannot find host");
System.exit(1);
} catch (SocketException e) {
System.err.println("Can't open socket");
e.printStackTrace();
System.exit(1);
}
System.out.println("ChatterClient starting");
}

public void run() {
try {
for (int i = 0; i < 25; i++) {
String outMessage = "Client #" + id + ",message #" + i;
s.send(Dgram.toDatagram(outMessage, hostAddress,
ChatterServer.INPORT));
s.receive(dp);
String rcvd = "Client #" + id + ",rcvd from " + dp.getAddress()
+ ", " + dp.getPort() + ":" + Dgram.toString(dp);
System.out.println(rcvd);
}
} catch (IOException e) {
e.printStackTrace();
System.exit(1);
}
}

public static void main(String[] args) {
for (int i = 0; i < 10; i++) {
new ChatterClient(i).start();
}
}
}