题目：
假设Tom和Jerry利用Java UDP进行聊天，请为他们编写程序。具体如下：
（1）、Tom和Jerry聊天的双方都应该具有发送端和接收端；
（2）、利用DatagramSocket与DatagramPacket；
（3）、实现 java.lang.Runnable类，重写 run()方法。
学过计网的都知道，利用三元组（ip地址，协议，端口）就可以标识网络的进程了。
而进行通信我们直接运用socket就可以了，首先需要知道是socket是什么，这部分可以参考这个大佬写的博客。
https://blog.csdn.net/pashanhu6402/article/details/96428887
实现一个客户端，那么需要Tom和Jerry都可以实现接收和发送功能，分别用两个线程启动。
接收线程Receive_Thread.java
package Chat_UDP;
import java.io.IOException;
import java.util.Date;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.text.SimpleDateFormat;
public class Receive_Thread extends Thread {
private static final int MAX_RECEIVE_BUFFER = 1024;
private DatagramSocket server;
private DatagramPacket packet;
byte[] buffer = new byte[MAX_RECEIVE_BUFFER];
public Receive_Thread(DatagramSocket server)
{
this.server = server;
packet = new DatagramPacket(buffer, buffer.length);
}
@Override
public void run() {
try
{
while(true)
{
//接收数据包
server.receive(packet);
String s = new String(packet.getData(),packet.getOffset(),packet.getLength(),"UTF-8");
Date day=new Date();
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
if(packet.getPort() == 10001)
System.out.println("Tom"+packet.getAddress()+" 说:"+s+"\t"+df.format(day));
else{
System.out.println("Jerry"+packet.getAddress()+" 说 :"+s+"\t"+df.format(day));
}
packet.setLength(buffer.length);
}
}
catch(IOException e)
{
System.out.println("IOException");
}
}
}
发送线程Send_Thread.java
package Chat_UDP;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.util.Scanner;
public class Send_Thread extends Thread{
//发送的socket端
private DatagramSocket sender = null;
//待发送的目标地址
private InetSocketAddress address = null;
//从键盘输入
Scanner scan = new Scanner(System.in);
public Send_Thread(DatagramSocket sender,InetSocketAddress address)
{
this.sender = sender;
this.address = address;
}
@Override
public void run() {
// TODO Auto-generated method stub
try
{
while(true)
{
//输入待发送的内容
String input = scan.nextLine();
if(input.equals("exit"))
break;
byte[] data = null;
data = input.getBytes("UTF-8");
//创建UDP数据报
DatagramPacket pack = new DatagramPacket(data, data.length,address);
sender.send(pack);
}
System.out.println("Exit!");
}catch(IOException e)
{
System.out.println("IOException");
}
}
}
聊天服务器
Chat_Server.java
package Chat_UDP;
//杨丽冰 201831064402
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
public class Chat_Server {
private static final int DEST_PORT = 8888;
private static final int SEND_PORT = 10001;
private static final int RECE_PORT = 9000;
private static final String IP = "127.0.0.1";
public static void main(String[] args)
{
try{
Send_Thread send_thread = null;
Receive_Thread rece_thread = null;
InetSocketAddress address = null;
//创建待接受数据包的目的机的端口号和IP地址
address = new InetSocketAddress(IP, DEST_PORT);
//创建发送的Socket端
DatagramSocket sendsocket = new DatagramSocket(SEND_PORT);
//创建接受的Socket端
DatagramSocket recesocket = new DatagramSocket(RECE_PORT);
//发送线程建立
send_thread = new Send_Thread(sendsocket, address);
//接受线程的建立
rece_thread = new Receive_Thread(recesocket);
send_thread.start();
rece_thread.start();
}catch(Exception e)
{
System.out.println("Exception!");
}
}
}
聊天客户端 Chat_Client.java
package Chat_UDP;
//杨丽冰 201831064402
import java.net.DatagramSocket;
import java.net.InetSocketAddress;
public class Chat_Client {
//声明端口号
private static final int DEST_PORT = 9000;
private static final int SEND_PORT = 10000;
private static final int RECE_PORT = 8888;
private static final String IP = "127.0.0.1";
public static void main(String[] args)
{
try{
Send_Thread send_thread = null;
Receive_Thread rece_thread = null;
InetSocketAddress address = null;
//创建待接受数据包的目的机的端口号和IP地址
address = new InetSocketAddress(IP, DEST_PORT);
//创建发送的Socket端
DatagramSocket sendsocket = new DatagramSocket(SEND_PORT);
//创建接受的Socket端
DatagramSocket recesocket = new DatagramSocket(RECE_PORT);
//发送线程建立
send_thread = new Send_Thread(sendsocket, address);
//接受线程的建立
rece_thread = new Receive_Thread(recesocket);
send_thread.start();
rece_thread.start();
}catch(Exception e)
{
System.out.println("Exception!");
}
}
}
需要注意的时候运行的时候需要同时运行聊天服务器和客户端，才能够正常运行。
最终效果如下：
