//UDPServer.java
import java.net.*;
import java.io.*;
import java.util.*;
public class UDPServer {
static final int INPORT=1711;
private byte[] buf=new byte[1000];
private DatagramPacket dp=new DatagramPacket(buf,buf.length);
private DatagramSocket socket;
public UDPServer(){
try{
socket=new DatagramSocket(INPORT);
System.out.println("Server started!");
while(true){
socket.receive(dp);
String rcvd=Dgram.toString(dp)+",from ddress:"+dp.getAddress()+
",port:"+dp.getPort();
System.out.println(rcvd);
String echoString="Echoed:"+rcvd;
DatagramPacket echo=Dgram.toDatagram(echoString,dp.getAddress(),dp.getPort());
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 UDPServer();
}
}
//UDPClient.java
import java.lang.Thread;
import java.net.*;
import java.io.*;
public class UDPClient 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 UDPClient(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);
}
}
public void run(){
try{
for(int i=0;i<1;i++){//消息数
String outMessage="Client #"+
id+",message#"+i;
s.send(Dgram.toDatagram(outMessage,hostAddress,UDPServer.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<1;i++)//客户数量
new UDPClient(i).start();
}
}
//Dgram.java 数据报格式
import java.net.*;
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 String toString(DatagramPacket p){
return new String(p.getData(),0,p.getLength());
}
}
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