java - 在 Java 中多线程处理这个网络代码？

Question

我正在尝试在 C-S 框架上构建一个聊天应用程序，但我还没有完全弄清楚如何对客户端代码进行多线程处理。如果有人能指出我正确的方向，我将不胜感激。

对于初学者来说，这段代码仅允许客户端和服务器进行双向通信:

我不会粘贴整个代码，只粘贴最重要的部分

服务器

// main
public static void main (String[] args) {
    ChatServer cs = new ChatServer();
    cs.runServer();
}

// run ChatServer
public void runServer() {
    try {
        server = new ServerSocket (12345, 100);

        while (true) {
            try {
                waitForConnection();    // wait for connection
                getStreams();           // get IO streams
                processConnection();    // process connection
            } catch (EOFException eofException) {
                System.out.println("Server terminated connection");
            } finally {
                closeConnection();      // close connection
                ++counter;
            }
        }
    } catch (IOException ioException) {
        ioException.printStackTrace();
    }
}

// wait for connection, and display connection info
private void waitForConnection() throws IOException {
    System.out.println("Waiting for connection");
    connection = server.accept();
    System.out.println("Connection: " + counter + " received from: " + 
                    connection.getInetAddress().getHostName());
}

// get streams to send and receive data
private void getStreams() throws IOException {
    // set up output stream
    output = new ObjectOutputStream(connection.getOutputStream());
    output.flush();                     // flush output buffer to send header information

    // set up input stream
    input = new ObjectInputStream(connection.getInputStream());

    System.out.println("Got I/O streams");
}

private void processConnection() throws IOException {
    String message = "Connection succesful";
    sendData(message);

    do {    // process messages sent from client
        try {
            message = (String) input.readObject();  // read new message
            System.out.println(message);        // display message
        } catch (ClassNotFoundException classNotFoundException) {
            System.out.println("Unkonwn object type received!");
        }
    } while (!message.equals("CLIENT>>> TERMINATE"));
}

客户端

public static void main (String[] args) {
    Client application;

    // if no command line args
    if (args.length == 0) {
        application = new Client("127.0.0.1");
    } else {
        application = new Client(args[0]);
    }
}

// connect to server and process messages from server
public void runClient() {
    try {
        connectToServer();      // create Socket to connect to server
        getStreams();           // get input and output streams
        processConnection();    // process connection
    } catch (IOException ioException) {
        ioException.printStackTrace();
    } finally {
        closeConnection();
    }
}

// connect to server
private void connectToServer() throws IOException {
    displayMessage("Attempting connection\n");

    // create Socket to connect to server
    client = new Socket(InetAddress.getByName(chatServer), 12345);

    // dispaly connection information
    displayMessage("Connected to: " + client.getInetAddress().getHostName());
}

// get streams to send and receive data
private void getStreams() throws IOException {
    // set up output stream for objects
    output = new ObjectOutputStream(client.getOutputStream());
    output.flush();

    // set up input stream for objects
    input = new ObjectInputStream(client.getInputStream());

    displayMessage("\nGot I/O streams\n");
}

// process connection with server
private void processConnection() throws IOException {
    // enable enter field to send messages
    setTextFieldEditable(true);

    do {
        try {
            message = (String)input.readObject();
            displayMessage("\n" + message);
        } catch (ClassNotFoundException classNotFoundException) {
            displayMessage("\nUnknown object type received!");
        }
    } while (!message.equals("SERVER>>> TERMINATE"));
}

// close streams and socket
private void closeConnection() {
    displayMessage("\nClosing connection");
    setTextFieldEditable(false);

    try {
        output.close();
        input.close();
        client.close();
    } catch (IOException ioException) {
        ioException.printStackTrace();
    }
}

我最初的想法:

1. Client 类应该实现 runnable，但我不确定 run() 方法应该包含什么...

2. Server 类 - 我感觉关键在 accept() 行，但我不确定如何继续...

我才开始学习 Java 中的多线程，但我们最近预计将构建这个多线程网络聊天应用程序，所以我有点不知道如何继续。

非常感谢任何有关此问题的指导，谢谢!

Answer 1

为了让这个答案简短，你基本上需要，

1. 在实现Runnable的类中提取方法getStreams()和processConnecion()。这些方法将在线程中运行
2. 在waitForConnection()之后，构建新的Runnable类，注入(inject)您的connection(或Streams)和start()它<

多线程非常非常困难，Java 也不异常(exception)。在您的应用程序走得太远之前，请确保您完全了解Java Memory Model如何有效并遵循简单的规则:

• 使变量尽可能不可变
• 尽可能避免全局变量或实例变量
• 不要重新发明轮子，使用(滥用) java.util.concurrent 中的类包
• 不要在所有地方使用synchronized“以防万一”:您的应用会效率低下，并且可能在单个线程上运行得更好

作为多线程模型的替代方案，请使用Akka查看Actors。图书馆