服务器套接字在 Java 中无限期地读取客户端消息

Question

在我简单的 Java 客户端-服务器程序中，当向服务器发送消息并在那里读取时，readInt() 无限期地读取，使程序停留在那里。

我确保我只是发送和接收一个 int，没有别的，正如你可以从代码中看出的那样（我也尝试过在发送的消息中添加和不添加 \n 以查看它是否会结束):

相关客户代码

Socket server = new Socket("127.0.0.1", 2424);
DataOutputStream outputStream = new DataOutputStream(server.getOutputStream());
DataInputStream inputStream = new DataInputStream(server.getInputStream());
outputStream.writeInt(Protocol.Message.HANDSHAKE);
outputStream.write('\n'); // I tried with and without this
outputStream.flush();

相关服务器代码

ServerSocket socket = new ServerSocket(2424);
System.out.println("Listening on port 2424");

while (connected) {
    Socket client = socket.accept();
    System.out.println("SERVER: Going to read a message"); // This shows
    int messageType = (new DataInputStream(client.getInputStream())).readInt();
    System.out.println("SERVER: Received a message (" + messageType + ")"); // This does not
    commands.execute(messageType);
}

应该在readInt() 之后打印的消息从未见过。我以为会，因为我只发送一个 int 并接收一个 int（4 字节），这不像我发送的数据比预期的多。

我应该如何结束 readInt()？我是否必须发送空字节或其他内容？

编辑：实际服务器代码（使用线程）。

ServerSocket socket = new ServerSocket(2424);
System.out.println("Listening on port 2424");

while (connected) {
    Socket client = socket.accept();
    Worker worker = new Worker(client);
    worker.start();
}

工作线程

public class Worker extends Thread {
    private final Socket client;
    private final Commands commands;

    private final DataOutputStream outputStream;
    private final DataInputStream inputStream;

    public Worker(Socket client) throws IOException {
        System.out.println("SERVER: Handling client message");
        this.client = client;

        outputStream = new DataOutputStream(client.getOutputStream());
        inputStream = new DataInputStream(client.getInputStream());

        commands = new Commands();
        commands.addCommand(Protocol.Message.HANDSHAKE, new HandshakeCommand());
        //commands.addCommand(Protocol.Message.RECEIVE_FILE, new ReceiveFileCommand());
    }

    @Override
    public void run() {
        System.out.println("SERVER: Running thread for client message");
        try {
            int messageType = inputStream.readInt();

            System.out.println("SERVER: Received a message (ID " + messageType + ")");
            commands.execute(messageType);
        } catch (IOException | UnknownCommandException ex) {
            System.out.println(ex);
        }
    }
}

Answer 1

如xander 所说，它从未读取的原因是因为没有发送任何内容。这是我的错，我没有包括实际的客户端代码，只有服务器代码和客户端代码的最小化版本。

我试图在客户端的 while() 循环之后发送消息（它还等待来自服务器的消息）。

解决方案是将客户端的监听部分委托给另一个线程，这样它就不会阻塞需要将消息发送到服务器的主线程。

服务器套接字在 Java 中无限期地读取客户端消息

Server Socket reads Client message indefinitely in Java

java

sockets

client-server

datainputstream

dataoutputstream