Java编写UDP两个主机之间互相发送和接收数据包

好的，我可以为你提供一个简单的Java程序，实现UDP两个主机之间互相发送和接收数据包。

首先，你需要了解一下UDP协议和Java中的DatagramSocket和DatagramPacket类。UDP协议是一种无连接的协议，不保证可靠传输，但是传输速度快，适用于对实时性要求较高的场景。DatagramSocket和DatagramPacket是Java中用于实现UDP通信的类。

下面是一个简单的Java程序，实现两个主机之间互相发送和接收数据包：

import java.net.*;

public class UDPSenderReceiver {
    public static void main(String[] args) throws Exception {
        int port = 12345;
        InetAddress receiverAddress = InetAddress.getByName("接收方主机IP地址");

        DatagramSocket senderSocket = new DatagramSocket();
        DatagramSocket receiverSocket = new DatagramSocket(port);

        Sender sender = new Sender(senderSocket, receiverAddress, port);
        Receiver receiver = new Receiver(receiverSocket);

        sender.start();
        receiver.start();
    }
}

class Sender extends Thread {
    private DatagramSocket senderSocket;
    private InetAddress receiverAddress;
    private int port;

    public Sender(DatagramSocket senderSocket, InetAddress receiverAddress, int port) {
        this.senderSocket = senderSocket;
        this.receiverAddress = receiverAddress;
        this.port = port;
    }

    public void run() {
        try {
            BufferedReader inFromUser = new BufferedReader(new InputStreamReader(System.in));

            while (true) {
                byte[] sendData = new byte[1024];

                String sentence = inFromUser.readLine();
                sendData = sentence.getBytes();

                DatagramPacket sendPacket = new DatagramPacket(sendData, sendData.length, receiverAddress, port);
                senderSocket.send(sendPacket);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

class Receiver extends Thread {
    private DatagramSocket receiverSocket;

    public Receiver(DatagramSocket receiverSocket) {
        this.receiverSocket = receiverSocket;
    }

    public void run() {
        try {
            while (true) {
                byte[] receiveData = new byte[1024];

                DatagramPacket receivePacket = new DatagramPacket(receiveData, receiveData.length);
                receiverSocket.receive(receivePacket);

                String modifiedSentence = new String(receivePacket.getData());
                System.out.println("FROM SERVER:" + modifiedSentence);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

在程序中，我们创建了两个线程Sender和Receiver，分别用于发送和接收数据包。Sender从控制台读取用户输入的信息，并将信息发送给接收方主机；Receiver监听本地端口，接收来自发送方主机的数据包，并将数据包中的信息打印在控制台上。

你需要根据实际情况填写接收方主机的IP地址和端口号。在运行程序时，你可以在控制台上输入信息并发送给接收方主机，同时也可以接收来自接收方主机的信息。

以上就是一个简单的Java程序，实现UDP两个主机之间互相发送和接收数据包。希望能对你有所帮助！