我想寫一個簡單的控制檯程序,允許我發送和接收字符串消息。我遇到的問題是,我不知道如何同時運行接收代碼和發送代碼。如何同時運行這兩個循環? (Java)
個別地,類正在工作。我可以接收數據包併發送數據包,但是讓它們一次運行似乎對我來說是不可能的。
我研究過多線程,但由於我的知識仍然非常基礎,我似乎無法理解它是如何工作的。
這是我目前使用的代碼。我自己編寫了Dialog類,並在互聯網上找到了另外兩個類。
Dialog類:
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;
}
}
接收類:
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);
}
}
}
發送類:
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();
}
}
}
此外,有沒有什麼辦法來測試,如果我可以接收數據包?我一直在和一位朋友一起測試它,但自己做起來會更方便。
謝謝!
難道你只是讓兩個程序互相交談,而不是試圖在一個? – doctorlove
嗯,我想將代碼發送給我的朋友,看看是否可以通過控制檯聊天。這意味着它需要監聽數據包並允許同時發送數據包。 – Daan
與問題無關的注意事項:考慮使用Executors/ThreadFactory而不是創建Thread的子類:http://docs.oracle.com/javase/7/docs/api/java/util/concurrent/package-summary.html – Puce