如何让 UDP 服务器和客户端同时监听传入和传出数据包

Question

我正在尝试在 Java 中实现一个简单的 UDP 连接，我希望客户端和服务器都在监听传入的消息并准备好同时发送消息。

目前，该程序使得服务器开始侦听传入的数据包，因此客户端发送第一条消息。

如果可能的话，我真的很想知道一种简单的方法来实现它。

这是客户端的代码：

class EchoClient 
{
    public static void main( String args[] ) throws Exception 
    {
        System.out.println("\nWelcome to UDP Client");
        System.out.println("---------------------------------------------------");
        
        Scanner sc = new Scanner (System.in);
        
        DatagramSocket socket = new DatagramSocket();
        socket.setSoTimeout(120000);

        while (true)
        {
            //Send
            System.out.print("\nEnter message: ");
            String msg = sc.nextLine();         
            byte[] buffer = msg.getBytes();
            DatagramPacket packetS = new DatagramPacket(buffer,buffer.length,InetAddress.getByName(args[0]),1500);
            socket.send( packetS );
            
            //Receive
            DatagramPacket packetR = new DatagramPacket(new byte[512],512);
            socket.receive( packetR );
            System.out.println( "Alice at: "+new Date()+" "+packetR.getAddress()+":"+packetR.getPort()+"\nSays: "+new String(packetR.getData(),0,packetR.getLength()) );
        }
    }
}

以及服务器的代码：

class EchoServer 
{
    public static void main( String args[] ) throws Exception 
    {
        System.out.println("\nWelcome to UDP Server");
        System.out.println("---------------------------------------------------");

        Scanner sc = new Scanner (System.in);
        
        DatagramSocket socket = new DatagramSocket(1500);
    
        //Message loop
        while ( true ) 
        {   
            //Receiving
            DatagramPacket packetR = new DatagramPacket(new byte[512],512);
            socket.receive( packetR );
            System.out.println("Bob at: "+new Date()+" "+packetR.getAddress()+":"+packetR.getPort()+"\nSays: "+new String(packetR.getData(),0,packetR.getLength()) );
    
            //Send
            System.out.print("\nEnter message: ");
            String msg = sc.nextLine();
            byte[] buffer = msg.getBytes();
            DatagramPacket packetS = new DatagramPacket(buffer,buffer.length,packetU.getAddress(),packetU.getPort());
            socket.send( packetS );
        }
    }
}

Answer 1

您好，一个简单的方法是在主线程中启动多个线程。

class EchoServerClient 
{
    public static void main( String args[] ) throws Exception 
    {
        new Thread(() -> {
            EchoServer.main(args) //You can also rename main by another name
        }).start();
        new Thread(() -> {
            EchoClient.main(args) //You can also rename main by another name
        }).start();
    }
}