多客户端 java 客户端 服务器 聊天

Question

我正在尝试编写一个多客户端服务器聊天。一切都应该在同一台计算机上运行，​​每个客户端都在不同的 shell 终端控制台中。我在这边读了几个线程，人们说我应该在服务器上为每个连接的客户端运行新线程。这就是我所做的。不过，服务器仍在其控制台上打印来自每个客户端的消息，但客户端只能看到他们编写的消息，而不是在聊天中提交的每条消息。我应该怎么做才能解决它？

代码如下： 服务器：

//package javauj.serwer;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;


public class Server {
    private static final int PORT_NUM = 5051;
    private static ServerSocket serS;
    private static Socket s;

    public static void main(String[] args) throws IOException{
        DateFormat df = new SimpleDateFormat("dd/MM/yy HH:mm:ss");
        Calendar cal = Calendar.getInstance();
            System.out.println(df.format(cal.getTime())+" Server waiting on port "+PORT_NUM);
            try {
                serS = new ServerSocket(PORT_NUM);
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }



        while(true){
            try {
                s = serS.accept();
                System.out.println("New user connected");
                    ServerThread st=new ServerThread(s);
                        st.start();


                } catch (IOException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }   





        }
    }
}   

服务器线程：

import java.io.IOException;
import java.io.PrintStream;
import java.net.Socket;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Scanner;


public class ServerThread extends Thread {
    Socket socket=null;
    private Scanner sc;
    private PrintStream ps;
    public ServerThread(Socket s) {
        this.socket=s;

    }



        public void run(){
            DateFormat df = new SimpleDateFormat("dd/MM/yy HH:mm:ss");
            Calendar cal = Calendar.getInstance();
            String response;    
                while(true){    
                try {
                        sc = new Scanner(socket.getInputStream());
                        ps = new PrintStream(socket.getOutputStream());
                } catch (IOException e) {
                            // TODO Auto-generated catch block
                        e.printStackTrace();
                }

                if((response=sc.nextLine())!=null){


                    System.out.println(df.format(cal.getTime())+" Napisal "+response);

                    ps.println(df.format(cal.getTime())+" Napisal :"+response);

                    }   
            }


        }


}

和客户

import java.io.IOException;
import java.io.PrintStream;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.Scanner;




public class Client {
    static Scanner sc;
    static Scanner sc2;
    static Socket s;
    static String response;
    public static void main(String[]args) throws UnknownHostException, IOException{
        String send;
        sc=new Scanner(System.in);  //client send scanner
        s = new Socket("127.0.0.1", 5051);
        sc2 = new Scanner(s.getInputStream());  //client response scanner
        PrintStream ps = new PrintStream(s.getOutputStream());

        while(true){

            System.out.println(">");    
            send = sc.nextLine();

            ps.println(send);       
            // I tried run new thread for responses
            //Thread thread = new Thread(new Runnable(){
                //public void run(){
                    //while(true){
                        response=sc2.nextLine();        
                        System.out.println(response);
                //  }   
                //}
            //});
        }

    }
}

Answer 1

1. 您必须实现 ServerThread 实例和服务器之间的通信（例如通过接口）。必须通知服务器有关 ServerThread 获取的消息，然后将此消息转换为其他（先前建立的）套接字（必须跟踪）。

2. 您的客户端有两个扫描仪，但其中一个实际上在 nextLine() 调用时阻止了另一个。因此，您必须在单独的线程中运行其中一个扫描仪。

以下代码适用于我，但必须考虑线程安全：

public interface MessageListener {
  void acceptMessage(String message);
}

public class Server {
  private static final int PORT_NUM = 5051;
  private static ServerSocket serS;
  private static List<PrintStream> sockets = new ArrayList<PrintStream>();
  public static void main(String[] args) throws IOException{
    DateFormat df = new SimpleDateFormat("dd/MM/yy HH:mm:ss");
    Calendar cal = Calendar.getInstance();
    System.out.println(df.format(cal.getTime())+" Server waiting on port "+PORT_NUM);
    try {
        serS = new ServerSocket(PORT_NUM);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    MessageListener listener = new MessageListener() {
        @Override
        public void acceptMessage(String message) {
            Iterator<PrintStream> it = sockets.iterator();
            while (it.hasNext()) {
                PrintStream ps = it.next();
                ps.println("Have got message: " + message);
            }
        }
    };

    while(true){
        try {
            Socket s = serS.accept();
            sockets.add(new PrintStream(s.getOutputStream()));
            System.out.println("New user connected");
            ServerThread st=new ServerThread(s, listener);
            st.start();

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }



    }
}


public class ServerThread extends Thread {
  Socket socket=null;
  private Scanner sc;
  //private PrintStream ps;
  private final MessageListener listener;

  public ServerThread(Socket s, MessageListener listener) {
    this.socket=s;
    this.listener = listener;
  }

  public void run(){
    DateFormat df = new SimpleDateFormat("dd/MM/yy HH:mm:ss");
    Calendar cal = Calendar.getInstance();
    String response;
    while(true){
        try {
            sc = new Scanner(socket.getInputStream());
            //ps = new PrintStream(socket.getOutputStream());
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        if((response=sc.nextLine())!=null){


            System.out.println(df.format(cal.getTime())+" Napisal "+response);

            //ps.println(df.format(cal.getTime())+" Napisal :"+response);
            listener.acceptMessage(response);
        }
      }


  }


}

public class Client {
  static Scanner sc;
  static Scanner sc2;
  static Socket s;
  static String response;
  public static void main(String[]args) throws UnknownHostException, IOException{
    String send;
    sc=new Scanner(System.in);  //client send scanner
    s = new Socket("127.0.0.1", 5051);
    ResponseListener l = new ResponseListener(new Scanner(s.getInputStream()));
    Thread t = new Thread(l);
    t.start();

    PrintStream ps = new PrintStream(s.getOutputStream());

    while(true){

        System.out.println(">");
        send = sc.nextLine();

        ps.println(send);
    }

}

static class ResponseListener implements Runnable {
    private final Scanner scanner;

    ResponseListener(Scanner scanner) {
        this.scanner = scanner;
    }

    @Override
    public void run() {
        while (true) {
            response = scanner.nextLine();
            System.out.println(response);
        }
    }
}

}

Answer 2

客户端需要两个线程：

• 用于读取来自服务器的消息
• 另一个线程从用户那里获取输入

第一个线程（来自服务器的读取器）只是读取传入的消息并将其打印到控制台

第二个线程（写入服务器）接收用户输入并将其发送到服务器。

实际上，在您的代码中，客户端上只有一个线程（主线程）。