[网络协议]Java多线程实现UDP本地网络聊天

1.新建一个类"xiaolin"，模拟一个账号为"xiaolin"的用户，代码如下：
public class xiaolin implements Runnable{
InetAddress inetAddress;
DatagramSocket datagramSocket;
String sentMessage=""; //发送消息
String receiveMessage=""; //接收消息
public xiaolin(InetAddress inetAddress, DatagramSocket datagramSocket) {
this.inetAddress = inetAddress;
this.datagramSocket = datagramSocket;
}

@Override
public void run() {  //开启线程
    /*
    当发送和接收到 “byb"时关闭，注意这里判断符号用||,但实际上要同时满足发送消息和接收消息为”byb“是才退出程序
    因为run函数中的while（true）阻塞，当这两者都满足是才退出
    * */
    if (receiveMessage.equals("byb") || sentMessage.equals("byb")) {  //
        datagramSocket.close();
    }
   else {
        if (Thread.currentThread().getName().equals("发送")) {  //发送消息线程执行的代码
            Scanner scanner = new Scanner(System.in);
            while (true) {
            if(receiveMessage.equals("byb"))        //当接收消息为”byb“退出
                break;
            if (scanner.hasNext()) {
                sentMessage = scanner.nextLine();
            }
           //发送消息数据包
            DatagramPacket datagramSent = new DatagramPacket(sentMessage.getBytes(), 0, sentMessage.getBytes().length, inetAddress, 8484);
            try {
                datagramSocket.send(datagramSent); //发送数据
            } catch (IOException e) {
                e.printStackTrace();
            }
            //接收
            if(sentMessage.equals("byb"))  //当发送消息为”byb“退出
                break;
              }
        } else if (Thread.currentThread().getName().equals("接收")) {  //接收消息执行代码

            byte[] buffer = new byte[1024];
            //接收消息数据包
            DatagramPacket datagramReceive = new DatagramPacket(buffer, 0, buffer.length);
            while (true) {
            if (sentMessage.equals("byb"))
                break;
                //接收
                try {
                    datagramSocket.receive(datagramReceive);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                int len = datagramReceive.getLength();
                receiveMessage = new String(datagramReceive.getData(), 0, len);
                System.out.println(receiveMessage);
            if (receiveMessage.equals("byb"))
                break;
            }
        }
   }
}

public static void main(String[] args) throws UnknownHostException, SocketException {
    //获取本机地址和开启端口
    InetAddress inetAddress=InetAddress.getLocalHost();
    DatagramSocket datagramSocket=new DatagramSocket(9090);
    xiaolin xl=new xiaolin(inetAddress,datagramSocket);
    //开启线程
    Thread sentT=new Thread(xl,"发送");
    Thread receiveT=new Thread(xl,"接收");
    sentT.start();
    receiveT.start();
}

}
2.然后新建一个类"xiaop"，模拟一个账号为"xiaop"的用户，来与"xiaolin"聊天,代码如下：
public class xiaop implements Runnable{
DatagramSocket datagramSocket;
InetAddress inetAddress;
String receiveMessage="";
String sentMessage="";

public xiaop(DatagramSocket datagramSocket, InetAddress inetAddress) {
    this.datagramSocket = datagramSocket;
    this.inetAddress = inetAddress;
}

@Override
public void run() {

    if (receiveMessage.equals("byb") || sentMessage.equals("byb")) {
        datagramSocket.close();
    }
    else {
        if(Thread.currentThread().getName().equals("发送")) {

            Scanner scanner = new Scanner(System.in);

            while (true) {
                if (receiveMessage.equals("byb"))
                    break;
                if (scanner.hasNext()) {
                    sentMessage = scanner.nextLine();
                }

                DatagramPacket datagramSent = new DatagramPacket(sentMessage.getBytes(), 0, sentMessage.getBytes().length, inetAddress, 9090);
                try {
                    datagramSocket.send(datagramSent);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                //接收
                if (sentMessage.equals("byb"))
                    break;
            }

        }
        else if (Thread.currentThread().getName().equals("接收")) {


            byte[] buffer = new byte[1024];
            DatagramPacket datagramReceive = new DatagramPacket(buffer, 0, buffer.length);
           while (true) {
                if (sentMessage.equals("byb"))
                    break;
                //接收
                try {
                    datagramSocket.receive(datagramReceive);
                } catch (IOException e) {
                    e.printStackTrace();
                }
                int len = datagramReceive.getLength();
                receiveMessage = new String(datagramReceive.getData(), 0, len);
                System.out.println(receiveMessage);
                if (receiveMessage.equals("byb"))
                    break;
            }
        }
    }
}

public static void main(String[] args) throws UnknownHostException, SocketException {
    InetAddress inetAddress=InetAddress.getLocalHost();
    DatagramSocket datagramSocket=new DatagramSocket(8484);
    xiaop xl=new xiaop(datagramSocket,inetAddress);
    Thread sentT=new Thread(xl,"发送");
    Thread receiveT=new Thread(xl,"接收");
    sentT.start();
    receiveT.start();
}

}
3.运行结果如下：