9

我对此感到非常困惑:当我在 Eclipse 中正常运行程序时,我的某些代码无法正常工作,但是当我使用调试模式分别运行每个步骤时,它确实可以正常工作。

代码:

public void showConnectDialog() {
    ConnectDialog connectDialog = new ConnectDialog();
    connectDialog.setVisible(true);
    //Until here, code runs
    while(! connectDialog.getConnected()) {};
    //The next line does only run in debug
    JOptionPane.showMessageDialog(connectDialog, "Connected", "Connected", JOptionPane.INFORMATION_MESSAGE);

}

连接器(一旦用户在对话框中点击“连接”,就会启动(作为线程)):

private class ServerConnector implements ActionListener, Runnable {

    @Override
    public void actionPerformed(ActionEvent e) {
        if (! IP_field.getText().equals("")) {
            if (! isConnecting) {
                new Thread(new ServerConnector(), "ServerConnector").start();

            }

        }
        else {
            JOptionPane.showMessageDialog(dialog, 
                                          "Enter an IP address", 
                                          "Enter IP", 
                                          JOptionPane.WARNING_MESSAGE);

        }

    }

    @Override
    public void run() {
        try {
            setConnecting(true);
            Socket socket = connect();
            if (socket != null) {
                ObjectOutputStream oOut = new ObjectOutputStream(socket.getOutputStream());
                ObjectInputStream oIn = new ObjectInputStream(socket.getInputStream());
                if (login(oOut, oIn)) {
                    isConnected = true;
                    setConnecting(false);

                }
                else {
                    socket.close();

                }

                setConnecting(false);

            }

        }
        catch (RSPException e) {
            e.printStackTrace();
            System.exit(1);

        }
        catch (Exception e) {
            //If an exception occurs, setConnecting() will be true. This 
            //not good, so it has to be set to false
            e.printStackTrace();
            setConnecting(false);

        }

    }

    private boolean login(ObjectOutputStream oOut, ObjectInputStream oIn) 
            throws ClassNotFoundException, IOException, RSPException {
        //Send login request action:
        oOut.writeObject(new LoginAction(ActionSender.CLIENT, getID(), 
                                         getPassword()));

        Object obj = oIn.readObject();
        if (obj instanceof LoginActionResult) {
            LoginActionResult result = (LoginActionResult) obj;
            if (result.getResult() == LoginResults.SUCCES) {
                return true;

            }
            else if (result.getResult() == LoginResults.FAIL_ON_ID) {
                JOptionPane.showMessageDialog(dialog, 
                                              "Invalid password or ID", 
                                              "Can't login", 
                                              JOptionPane.ERROR_MESSAGE);
                return false;

            }
            else if (result.getResult() == LoginResults.FAIL_ON_PASSWORD) {
                JOptionPane.showMessageDialog(dialog, 
                                              "Invalid password or ID", 
                                              "Can't login", 
                                              JOptionPane.ERROR_MESSAGE);
                return false;

            }
            else if (result.getResult() == LoginResults.SERVER_FULL) {
                JOptionPane.showMessageDialog(dialog, 
                                              "Couldn't connect: \n" +
                                              "Server is full", 
                                              "Failed to connect", 
                                              JOptionPane.WARNING_MESSAGE);
                return false;

            }
            else {
                return false;

            }

        }
        else {
            System.out.println(obj);
            throw new RSPException("Server is not following the protocol.");

        }

    }

    private void setConnecting(boolean connecting) {
        if (connecting) {
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    connectButton.setEnabled(false);

                }
            });
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    connectButton.setText("Connecting...");

                }
            });

        }
        else {
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    connectButton.setText("Connect");

                }
            });
            SwingUtilities.invokeLater(new Runnable() {

                @Override
                public void run() {
                    connectButton.setEnabled(true);

                }
            });

        }

        isConnecting = connecting;

    }

    private String getAddressFromTextField() {
        return IP_field.getText();

    }

    private InetAddress getInetAddress(String fullAddress) {
        try {
            if (fullAddress.contains(":")) {
                String[] splitAddress = fullAddress.split(":");
                return InetAddress.getByName(splitAddress[0]);

            }
            else {
                return InetAddress.getByName(fullAddress);

            }
        }
        catch (UnknownHostException e) {
            return null;

        }

    }

    private int getPort(String fullAddress) {
        try {
            String[] splittedAddress = fullAddress.split(":");
            return Integer.valueOf(splittedAddress[1]);

        }
        catch (NumberFormatException ex) {
            return -1;

        }
        catch (NullPointerException 
             | ArrayIndexOutOfBoundsException 
             | PatternSyntaxException ex) {
            //Returning default port value: 25566, because no port was given
            return 25566;

        }

    }

    @SuppressWarnings("resource")
    private Socket connect() {
        Socket socket = null;

        InetAddress address = null;
        if ((address = getInetAddress(getAddressFromTextField())) == null) {
            return null;

        }
        int port = getPort(getAddressFromTextField());

        try {
            socket = new Socket(address, port);

        }
        catch (ConnectException e ) {
            Socket retrySocket = null;
            if ((retrySocket = retryConnect(address, port)) == null) {
                JOptionPane.showMessageDialog(dialog,
                                              "Connection timed out", 
                                              "Failed to connect", 
                                              JOptionPane.ERROR_MESSAGE);
                setConnecting(false);

            }
            else {
                socket = retrySocket;

            }

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

        }

        return socket;

    }

    private Socket retryConnect(InetAddress address, int port) {
        Thread waitThread = new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    //Will wait 15(000) (milli)seconds before stopping with
                    //trying to connect.
                    //One second (1000 millis) is for debugging and testing
                    Thread.sleep(1000);

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

                }

            }

        });

        waitThread.start();

        while (waitThread.isAlive()) {
            try {
                return new Socket(address, port);

            }
            catch (ConnectException e) {
                //Do nothing, will re-attempt to connect.

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

            }

        }

        return null;

    }

    private String getID() {
        return ID_field.getText();

    }

    private String getPassword() {
        if (getID().equals("master")) {
            return "masterPassword";

        }
        else {
            return new String(passwordField.getPassword());

        }

    }

}

getConnected()true连接到服务器后立即返回。连接器在单独的线程上运行。

编辑:我试图将代码放在getConnected()while 块中,然后它就可以工作了。为什么它会起作用而不是其他?

4

4 回答 4

5

我有同样的问题,但有更多的规范。该代码在 32 位中运行良好,但在 64 位中我遇到了这个问题(我使用的是本机库,所以我需要同时维护两者)。

我找到的解决方案是在 while 循环中添加 Thread.sleep() 。我不知道它为什么起作用,所以你的猜测和我的一样好。

更好的解决方案可能是实现观察者模式而不是无限循环。但这需要一些重构。

于 2013-09-24T14:00:57.737 回答
2

我遇到了一个非常相似的问题,即无法运行的“while”循环,该循环是我的主要例程。我如何让循环运行是循环中完成的第一件事是睡眠:

    try
        {Thread.sleep(0);}
    catch (Exception e)
        {e.printStackTrace();}

这足以让一切顺利进行。

于 2015-05-31T08:03:55.243 回答
2

正如其他答案所建议的那样,使用Thread.sleep()应该可以解决问题,但这不是一个很好的方法。相反,我们应该使用Thread.yield().

为什么yield而不是sleep

请参阅: Thread.Sleep(0) 和 Thread.Yield() 之间的区别以及Thread.sleep(0) 和 Thread.yield() 语句是否等效?

为什么这行得通?

当我们只运行线程时,操作系统将它们置于“空闲”状态,而当它预期“唤醒”时,它不会。另一方面,在调试模式下,我们有一个受控的环境。操作系统几乎无法控制它,因为一切都在逐步缓慢地进行。如果我们在没有任何断点的情况下运行几次调试,在几次成功运行后,我们应该会看到相同的效果。

于 2016-02-11T14:28:01.357 回答
0

我在使用 UiObject2 wait(Until.findObject(),20) 的 UIAutomator 中遇到了同样的问题。

Thread.yield() - 为我工作

于 2018-07-03T08:28:10.147 回答