Java客户端-服务器应用程序中的EOFException

Question

我正在开发一个简单的客户端服务器时钟，该时钟将当前时间传输到由时钟服务器应用程序托管的所有客户端。 有一个定时事件（TimerTask），它定期将数据发送到所有客户端。 在服务器部分，它工作正常，但是当客户端运行时，即使它处于while循环中，它也只读取一次时间-跳转到catch块并引发EOFException。 while循环中的readUTF（）方法很可能会引发麻烦。 我该如何应对？

public class Client {

public static void main(String[] arg) {


    Socket socketConnection = null;
    ObjectOutputStream clientOutputStream = null;
    ObjectInputStream clientInputStream = null;

    try {

        socketConnection = new Socket("127.0.0.1", 11111);

        clientOutputStream = new ObjectOutputStream(
                socketConnection.getOutputStream());
        clientInputStream = new ObjectInputStream(
                socketConnection.getInputStream());     

        while(true){
            String date = clientInputStream.readUTF();
            clientOutputStream.flush();
            System.out.println(date);

        }

    } catch (Exception e) {
        System.out.println("The following exception has occured and was caught:");
        System.out.println(e);
    }

    finally{
        try {
            clientOutputStream.close();
            clientInputStream.close();              
            socketConnection.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }


}

例如，我可以将整个try / catch / finally块放入while循环中，然后工作正常。 但是这样，我的客户端每隔一秒钟就会断开连接并重新连接到服务器，这是不可接受的。 有任何想法吗？

编辑-stacktrace：

java.io.EOFException
at java.io.DataInputStream.readUnsignedShort(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.readUnsignedShort(Unknown Source)
at java.io.ObjectInputStream$BlockDataInputStream.readUTF(Unknown Source)
at java.io.ObjectInputStream.readUTF(Unknown Source)
at task2.Client.main(Client.java:28)

编辑-服务器代码：

public class Server {

 public static void main(String[] args) throws IOException {

        ServerSocket serverSocket = null;

        boolean listeningSocket = true;
        try {
            serverSocket = new ServerSocket(11111);
        } catch (IOException e) {
            System.err.println("Could not listen on port: 11111");
        }


        while(listeningSocket){
            System.out.println("Waiting for a client to connect...");
            Socket clientSocket = serverSocket.accept();
            System.out.println("Client connected!");
            ConnectThread ct = new ConnectThread(clientSocket);
            ct.start();
        }
        System.out.println("closed");
        serverSocket.close();       
    }

}

服务器一直在监听传入的客户端，并且每次接受连接时，它都会在由以下类定义的单独线程上启动对话：

public class ConnectThread extends Thread{

private Socket socket = null;
public ConnectThread(Socket socket) {
    super("ConnectThread");
    this.socket = socket;
}

@Override
public void run(){
    ObjectOutputStream serverOutputStream = null;
    ObjectInputStream serverInputStream = null;
    try {           
        serverOutputStream = new ObjectOutputStream(socket.getOutputStream());          
        serverInputStream = new ObjectInputStream(socket.getInputStream());

        ClockTask ctask = new ClockTask();
        Timer timer = new Timer();
        timer.schedule(ctask, 0, 1000);

        Thread.sleep(1000);
        serverOutputStream.writeUTF(ctask.date);
        serverOutputStream.flush();


    } catch (IOException | InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    finally{
        try {
            serverOutputStream.close();
            serverInputStream.close();              
            socket.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }       
}
}

计划定期更新日期：

public class ClockTask extends TimerTask {

public Calendar c;
public String date;

@Override
public void run() {
    DateFormat dateFormat = new SimpleDateFormat("HH:mm:ss");       
    this.c = Calendar.getInstance();
    this.date = dateFormat.format(c.getTime());
}

}

Answer 1

在ConnectThread运行时需要一个循环-就这样，它停止并且流关闭。

编辑代码：

ClockTask ctask = new ClockTask();
Timer timer = new Timer();
timer.schedule(ctask, 0, 1000);
while( true ){
    Thread.sleep(1000);
    serverOutputStream.writeUTF(ctask.date);
       serverOutputStream.flush();
}

Answer 2

您的服务器将日期一次写入流中，然后关闭。 因此，客户端在第一次读取后获取和EOFException。