更新双向 java 信使聊天以允许多个用户

Question

我刚刚完成了关于创建即时消息聊天的 youtube series，它通过套接字在服务器和一个客户端之间工作。但是，我想改进此聊天，以便多个客户端可以同时连接。

服务器工作正常，第一个客户端也是。在我打开的第一个客户端 window 上，我收到消息：

Attempting connection...
Connected to 127.0.0.1
Streams are now setup!
SERVER - You are now connected!

但是在第二个客户端 window 我打开，流没有设置，我只收到以下消息

Attempting connection...
Connected to 127.0.0.1

我听说我需要多线程来解决这个问题，但是我不太确定我该怎么做。

这些是我的文件：

ChatServerTest

import javax.swing.JFrame;

public class ChatServerTest {
    public static void main(String[] args) {
        ChatServer server =  new ChatServer();
        server.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        server.startRunning();
    }
}

ChatServer

import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ChatServer extends JFrame {

    private JTextField userText;
    private JTextArea chatWindow;
    private ObjectOutputStream output;
    private ObjectInputStream input;
    private ServerSocket server;
    private Socket connection;

    int port = 1234; // Test port

    //constructor (GUI)
    public ChatServer() {
        super("Instant Messenger (Server)");
        userText = new JTextField();
        userText.setEditable(false);
        userText.addActionListener(
                new ActionListener() {
                    public void actionPerformed(ActionEvent event){
                        sendMessage(event.getActionCommand());
                        userText.setText("");
                    }
                }
            );
        add(userText, BorderLayout.NORTH);
        chatWindow = new JTextArea();
        add(new JScrollPane(chatWindow));
        setSize(300,150);
        setVisible(true);
    }

    //set up and run the server
    public void startRunning(){
        try{
            server = new ServerSocket(port);
            while(true){
                try{
                    waitForConnection();
                    setupStreams();
                    whileChatting();
                }catch(EOFException eofException){
                    showMessage("\nServer ended the connection!");
                }finally{
                    closeCrap();
                }
            }
        }catch(IOException ioException){
            ioException.printStackTrace();
        }
    }

    //wait for connection, then display connection information
    private void waitForConnection() throws IOException{
        showMessage("Waiting for someone to connect... \n");
        connection = server.accept();
        showMessage("Now connected to " + connection.getInetAddress().getHostName());
    }

    //get stream to send and receive data
    private void setupStreams() throws IOException{
        output = new ObjectOutputStream(connection.getOutputStream());
        output.flush();
        input = new ObjectInputStream(connection.getInputStream());
        showMessage("\nStreams are now setup!\n");
    }

    //during the chat conversation
    private void whileChatting() throws IOException{
        String message = "You are now connected!";
        sendMessage(message);
        ableToType(true);
        do{
            try{
                message = (String) input.readObject();
                showMessage("\n" + message);
            }catch(ClassNotFoundException classNotFoundException){
                showMessage("\nERROR: Not a string");
            }
        }while(!message.equals("CLIENT - END"));
    }

    private void closeCrap(){
        showMessage("\nClosing connections...\n");
        ableToType(false);
        try{
            output.close();
            input.close();
            connection.close();
        }catch(IOException ioException){
            ioException.printStackTrace();
        }
    }

    //send a message to client
    private void sendMessage(String message) {
        try{
            output.writeObject("SERVER - " + message);
            output.flush();
            showMessage("\nSERVER - " + message);
        }catch(IOException ioExcenption){
            chatWindow.append("\nERROR: Can't send message");
        }
    }

    //updates chatWindow
    private void showMessage(final String text){
        SwingUtilities.invokeLater(
            new Runnable(){
                public void run(){
                    chatWindow.append(text);

                }
            }
        );
    }

    //let the user type stuff into their box
    private void ableToType(final boolean tof) {
        SwingUtilities.invokeLater(
            new Runnable(){
                public void run(){
                    userText.setEditable(tof);
                }
            }
        );
    }

}

ChatClientTest

import javax.swing.JFrame;

public class ChatClientTest {
    public static void main(String[] args) {
        String IP = "127.0.0.1";
        ChatClient client;
        client = new ChatClient(IP);
        client.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        client.startRunning();
    }
}

ChatClient

import java.io.*;
import java.net.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ChatClient extends JFrame {

    private JTextField userText;
    private JTextArea chatWindow;
    private ObjectOutputStream output;
    private ObjectInputStream input;
    private String message = "";
    private String serverIP;
    private Socket connection;

    int port = 1234; // Test port

    //constructor
    public ChatClient(String host){
        super("Instant Messenger (Client)");
        serverIP = host;
        userText = new JTextField();
        userText.setEditable(false);
        userText.addActionListener(
            new ActionListener(){
                public void actionPerformed(ActionEvent event){
                    sendMessage(event.getActionCommand());
                    userText.setText("");
                }
            }
        );
        add(userText, BorderLayout.NORTH);
        chatWindow = new JTextArea();
        add(new JScrollPane(chatWindow), BorderLayout.CENTER);
        setSize(300, 150);
        setVisible(true);

    }

    //connect to server
    public void startRunning(){
        try{
            connectToServer();
            setupStreams();
            whileChatting();
        }catch(EOFException eofException){
            showMessage("\nClient terminated connection.");
        }catch(IOException ioException){
            ioException.printStackTrace();
        }finally{
            closeCrap();
        }
    }

    //connect to server
    private void connectToServer() throws IOException{
        showMessage("Attempting connection...\n");
        connection = new Socket(InetAddress.getByName(serverIP), port);
        showMessage("Connected to " + connection.getInetAddress().getHostName());
    }

    //set up streams to send and receive messages
    private void setupStreams() throws IOException{
        output = new ObjectOutputStream(connection.getOutputStream());
        output.flush();
        input = new ObjectInputStream(connection.getInputStream());
        showMessage("\nStreams are now setup!");
    }

    //while chatting with server
    private void whileChatting() throws IOException{
        ableToType(true);
        do{
            try{
                message = (String) input.readObject();
                showMessage("\n" + message);
            }catch(ClassNotFoundException classNotFoundException){
                showMessage("\nUnknown object type");
            }
        }while(!message.equals("SERVER - END"));
    }

    //close the streams and sockets
    private void closeCrap(){
        showMessage("\nClosing down...");
        ableToType(false);
        try{
            output.close();
            input.close();
            connection.close();
        }catch(IOException ioException){
            ioException.printStackTrace();
        }
    }

    //send messages to server
    private void sendMessage(String message){
        try{
            output.writeObject("CLIENT - " + message);
            output.flush();
            showMessage("\nCLIENT - " + message);
        }catch(IOException ioException){
            chatWindow.append("\nMessage failed to send.");
        }
    }

    //change/update chatWindow
    private void showMessage(final String message){
        SwingUtilities.invokeLater(
            new Runnable(){
                public void run(){
                    chatWindow.append(message);

                }
            }
        );
    }

    //gives user permission to type text into the text box
    private void ableToType(final boolean tof){
        SwingUtilities.invokeLater(
            new Runnable(){
                public void run(){
                    userText.setEditable(tof);      
                }
            }
        );
    }

}

提前感谢并感谢我能得到的任何回复:)

Answer 1

虽然对于 SO 来说有点过于宽泛，但我将为您提供一个如何处理此类服务器-客户端程序的策略。如需更多信息，只需点击您最喜欢的搜索机即可。一定有很多文章。

一个服务器处理多个客户端请求的基本策略是这样的：

while (true) {
    accept a connection;
    create a thread to deal with the client;
    start that thread;
}

这样，新创建（和启动）的线程将运行并发。这让线程运行ning 此服务器代码返回到 while (true) 循环并停止在 "accept a connection" 行，有效地等待下一个客户端。

所以，基本上你应该有这样的东西

while (true) {
    connection = server.accept();
    Thread clientHandler = new Thread(new ClientHandler(connection));
    clientHandler.start();
}

这需要一个 class ClientHandler 实现 Runnable 来完成所有客户端通信。

请注意，您的程序中有许多部分需要重构。您的 class ChatServer 做的工作太多了。它甚至在扩展 JFrame。我的建议在同一个联盟中发挥作用，只是一个开始路径。通常，您不应该为每个传入的客户端请求创建一个新线程，而是使用一个有限的线程池。

更新双向 java 信使聊天以允许多个用户

Updating a two-way java messenger chat to allow multiplie users

java

multithreading

sockets

messenger

instant