java - readObject 挂起应用程序

Question

我正在尝试创建一个实时消息应用程序。但是，当尝试从 ObjectInputStream 读取对象时，代码无缘无故地挂起。没有抛出异常。

try {
    System.out.println("Trying to connect to server");
    socket = new Socket(InetAddress.getByName("localhost"),6789);
    System.out.println("Connected to server");

    inputStream = new ObjectInputStream(socket.getInputStream());

    outputStream = new ObjectOutputStream(socket.getOutputStream());
    outputStream.flush();

    System.out.println("Streams are set up.");

    window.toggleTyping(true);
    System.out.println("Typing is now enabled");

    String inputMsg = null;

    do {
        try {
            System.out.println("Reading object");
            inputMsg = (String)inputStream.readObject();
            System.out.println("Object read");

        } catch(ClassNotFoundException ee) {
            System.out.println("Clas not found exception");
            ee.printStackTrace();
        }

    } while(!inputMsg.equalsIgnoreCase("/exit"));

    closeConnection();

}catch(IOException ex) {
    ex.printStackTrace();
}

打印的最后一条消息是“Reading object”。

 try {
        serverSocket = new ServerSocket(6789);
            System.out.println("Socket created. About to accept connections");
            Socket s = serverSocket.accept();
            new Thread(new Chat(s)).start();

    } catch(IOException e) {
        e.printStackTrace();
    }

和类(class)聊天:

    public class Chat implements Runnable {

private Socket socket;
private ObjectOutputStream outputStream;
private ObjectInputStream inputStream;

public Chat(Socket s) {
    System.out.println("Chat class constructor called");
    this.socket = s;

    try {
        outputStream = new ObjectOutputStream(socket.getOutputStream());
        outputStream.flush();

        inputStream = new ObjectInputStream(socket.getInputStream());
        System.out.println("Chat streams are now set up");

    }catch(IOException ex) {
        ex.printStackTrace();
    }


}
private void closeChat() {
    try {
        outputStream.close();
        inputStream.close();
        socket.close();
        System.out.println("Chat is now closed");
    }catch(IOException ex) {
        ex.printStackTrace();
    }

}

@Override
public void run() {
    System.out.println("Chat class method run called");
    try {
        outputStream.writeObject("Connection is cool");
        outputStream.flush();
        System.out.println("Text sent");
        String inputMsg = "";
        do {

            try {
                inputMsg = (String)inputStream.readObject();
                System.out.println("Message read:"+inputMsg);
            }catch(ClassNotFoundException e) {
                e.printStackTrace();
            }
        }
        while(!inputMsg.equalsIgnoreCase("/exit"));
        closeChat();
    }
    catch (IOException e) {
        e.printStackTrace();
    }
}
}

每次聊天都是不同线程的原因是我计划有一天实现多个一对一聊天。

Answer 1

这是因为读取方法是阻塞方法。这意味着它正在尝试读取，直到得到-1，表明读取数据已完成。确保写入此套接字的 OutputStream 正在发送此消息。因此，您在发送套接字时调用 ObjectOutputStream.flush();写入数据后的方法或在写入后关闭输出流。关闭此流是不合理的，因为稍后您可能希望通过此流发送更多数据。

<小时/>

只是一般情况:创建输出流后不需要立即刷新它