Question

我正在尝试创建一个多线程聊天室，多个人可以附加到该聊天室。目的是当一个人发送一条消息时，该消息被打印在其他人的屏幕上。这是服务器代码：

package edu.fcps.ab;
import java.io.*;
import java.net.*;
import java.util.*;

public class TestServer implements Runnable{
    private int port;
    public static ServerSocket serverSock;
    public static Vector<PrintWriter> outputs = new Vector<PrintWriter>();
    public PrintWriter output;
    public BufferedReader input;
    public TestServer(int p) {
        port = p;
    }
    public static void main (String args[]) {
        Scanner scan = new Scanner(System.in);
        System.out.println("Enter port number");
        int port = scan.nextInt();
        TestServer ts = new TestServer(port);
        Thread t = new Thread(ts);
        t.start();
    }

    @Override
    public void run() {
        try {
            if(serverSock == null)
                 serverSock = new ServerSocket(port);
            Socket sock = serverSock.accept();
            TestServer ts = new TestServer(port);
            Thread t = new Thread(ts);
            t.start();
            output = new PrintWriter(sock.getOutputStream(), false);
            outputs.add(output);
            input = new BufferedReader(new InputStreamReader(sock.getInputStream()));
            while(t.isAlive()) {
                String message = input.readLine();
                if(message != null) {
                    System.out.println(message);
                    for(PrintWriter w : outputs) {
                        w.println(message);
                        w.flush();
                    }
                }
            }
        } catch(Exception e) {
            System.out.println("An error occurred");
            e.printStackTrace();
        }

    }

    public PrintWriter getOutput() {
        return output;
    }
}

这是客户端代码：

package edu.fcps.ab;
import java.io.*;
import java.net.*;
import java.util.*;
public class TestClient implements Runnable{
    private String username;
    public PrintWriter out;
    public static void main (String args[]) {
        TestClient tc = new TestClient();
        Thread t = new Thread(tc);
        t.start();
    }

    @Override
    public void run() {
        Scanner s = new Scanner(System.in);
        System.out.println("Enter port");
        int port = s.nextInt();
        String ip = "127.0.0.1";
        try {
            Socket sock = new Socket(ip, port);
            System.out.println("Successfully connected");
            System.out.println("Enter username");
            username = s.next();
            System.out.println("Welcome " + username);
            out = new PrintWriter(sock.getOutputStream(), true);
            out.println(username + " connected");
            InputStream stream = sock.getInputStream();
            Scanner input = new Scanner(stream);
            BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
            String sent;
            while(true) {
                if(stream.available() > 0) {
                    if(input.hasNextLine()) {
                        String message = input.nextLine();
                        String[] split = message.split(" ");
                        if(!(split[0].contains(username)))
                            System.out.println(message);
                    } 
                }
                sent = stdin.readLine();
                if(sent != null) {
                    out.println(username + ": " + sent);
                }
            }
        } catch(Exception e) {
            out.println(username + " disconnected");
        }
    }
}

当前，可以将多个人附加到该邮件上，并且该邮件将在服务器端打印出所有消息，但是并不能在所有客户端上打印这些消息。为什么会这样？

Answer 1

...但是消息并没有在所有客户端上打印。为什么会这样？

之所以发生这种情况，是因为所有客户端都调用stdin.readLine()并阻塞在那里，直到有输入行可用为止。此后，他们继续进行while(true)循环并打印最多一条消息，然后再次阻塞stdin.readLine()。

Java-使用套接字打印到多个输出

1 个答案: