java - 如何同时运行这两个循环？ ( java )

Question

我正在尝试编写一个简单的控制台程序，该程序允许我发送和接收字符串消息。但我遇到的问题是我不知道如何同时运行接收代码和发送代码。

就个人而言，类(class)正在运作。我可以接收数据包并发送数据包，但让它们立即运行对我来说似乎是不可能的。

我研究过多线程，但由于我的知识仍然非常基础，我似乎无法理解它的真正工作原理。

这是我当前正在使用的代码。我自己编写了 Dialog 类，并在互联网上找到了其他两个类。

对话框类:

import java.util.Scanner;


public class Dialog {

Scanner scanner = new Scanner(System.in);
User user = new User();
Network net = new Network();

ThreadReceive tr = new ThreadReceive();
ThreadSend ts = new ThreadSend();


public void run() {

    System.out.println("WELCOME");

    System.out.print("Port: ");
    while(!user.setPort(giveInput())) {
        System.out.println("Enter a valid port.");
    }

    System.out.print("IP: ");
    user.setIP(giveInput());

    System.out.println();
    System.out.println("--- CONVERSATION STARTED ---");

    tr.receive(user.getIP(), user.getPort()); // Starts receiving loop (within ThreadReceive class).

    while (true) { // Starts sending loop.
        ts.sendMessage(giveInput(), user.getIP(), user.getPort()); // Sends packet when input is given.
    }

}


private String giveInput() {

    String input = scanner.nextLine();
    return input;

}

}

接收类:

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;

public class ThreadReceive extends Thread {

public void receive(String ip, int port) {

    try {

        // Create a socket to listen on the port.
        DatagramSocket dsocket = new DatagramSocket(port);

        // Create a buffer to read datagrams into. If a
        // packet is larger than this buffer, the
        // excess will simply be discarded!
        byte[] buffer = new byte[2048];

        // Create a packet to receive data into the buffer
        DatagramPacket packet = new DatagramPacket(buffer, buffer.length);

        // Now loop forever, waiting to receive packets and printing them.
        while (true) {
            // Wait to receive a datagram
            dsocket.receive(packet);

            // Convert the contents to a string, and display them
            String msg = new String(buffer, 0, packet.getLength());
            System.out.println(packet.getAddress().getHostName() + ": " + msg);

            // Reset the length of the packet before reusing it.
            packet.setLength(buffer.length);
        }

    }

    catch (Exception e) {
        System.err.println(e);
    }

}

}

发送类:

import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;


public class ThreadSend extends Thread {

public void sendMessage(String message, String ip, int port) {

        try {
            byte[] data = message.getBytes();

            InetAddress address = InetAddress.getByName(ip);

            DatagramPacket packet = new DatagramPacket(data, data.length, address, port);

            DatagramSocket datagramSocket = new DatagramSocket();
            datagramSocket.send(packet);
        } 

        catch (Exception e) {
            e.printStackTrace();
        }
    }

}

还有，有什么方法可以测试是否可以接收数据包吗？我已经和 friend 一起测试过，但自己做会方便得多。

谢谢!

Answer 1

您没有正确使用线程。

逻辑应该在 run 中方法。

我建议您使用queue例如 ArrayBlockingQueue 将参数传递给线程。例如，您可以有一个方法将元素添加到此队列

public void addMessage(String message) {
     synchronized(inputQueue) {
          inputQueue.offer(r);
          inputQueue.notify();
     }
}

run 方法将像这样使用这些元素:

public void run() {
        try {
            while(!running) 
                    synchronized (inputQueue) {
                        inputQueue.wait();  // you can have a timeout also...
                            String message = this.inputQueue.poll();
                              // use the message item....
                              // in your case send it to the other user.
                        }
                    }       
                }
        } catch (Exception e) {
            /////// your exception handler
        }
}

另外记住启动您的主题:

Thread t = new MyThread();
t.start(); /// Start the thread !!!

PS:消息可以是任何对象，这里使用的是字符串，因为我基于我使用的一些代码

Queue<String>