java - 无法让 Thread.interrupt 工作

Question

我有一个程序执行一些文件 I/O，然后 hibernate 几秒钟，检查文件是否已更改，如果相同则 hibernate 。如果它们已更改，它会执行相同的文件 I/O，然后返回 hibernate 状态。我想实现一个击键，如果按下它会唤醒这个线程，但我无法让线程处理 InterruptedException。我的(简化的)代码在这里:

import java.awt.Color;
import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class StackOverFlowExample extends JFrame{

    private class MyDispatcher implements KeyEventDispatcher {
        boolean keyEventDone = false;

        @Override
        public boolean dispatchKeyEvent(KeyEvent e) {
            if(e.getID() == KeyEvent.KEY_PRESSED){
                if((e.getKeyCode() == 80 && e.getModifiers() == 11) && !keyEventDone){
                    System.out.println("interrupting");
                    interrupt();
                }
            }
            if (e.getID() == KeyEvent.KEY_RELEASED) {
                if(e.getKeyCode() == 80){
                    keyEventDone = false;
                }
            }
            return true;
        }

    }

public void interrupt(){
    System.out.println("recieved interrupt");
    Thread.currentThread().interrupt();
}

public static void main(String[] args){
    String fileName = "file Name";
    String oldFileName = "oldFileName";
    JFrame frame = new StackOverFlowExample();
    frame.setUndecorated(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
    frame.setSize(217, 104);

    do{
        if(!fileName.equals(oldFileName)){

        }else{
            try {
                System.out.println("Same file");
                Thread.sleep(10000);
            } catch (InterruptedException e) {
                System.out.println("continuing");
                if(Thread.currentThread().isInterrupted()){
                    System.out.println("continuing");
                    continue;
                }
                e.printStackTrace();
            }
        }
        oldFileName = fileName;
    }while(true);

}
public StackOverFlowExample(){
    super("");
    JPanel pane = new JPanel();
    pane.setBackground(Color.LIGHT_GRAY);
    setContentPane(pane);
    KeyboardFocusManager manager = 
    KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.addKeyEventDispatcher(new MyDispatcher());
}

}

类(class)中还有其他内容，但都与线程或任何内容无关。此外，我知道检查文件名不是执行此操作的最佳方法，但在我的应用程序中，如果文件不同，文件名将始终不同，因为文件名是根据时间生成的。

当我按“ctrl+shift+alt+p”唤醒线程时，它从 MyDispatcher 类打印出“interrupting”，从主类的中断方法打印出“recieved interrupt”，但没有别的，线程只是继续 sleep

我见过的所有中断 hibernate 线程的例子都有不在主类中的线程。这就是我的不起作用的原因吗？

Answer 1

同样，您打断了错误的线程，并希望传递正确的线程。例如，获取您的代码:

import java.awt.Color;
import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

@SuppressWarnings("serial")
public class StackOverFlowExample extends JFrame {
    static String oldFileName = "oldFileName";
    private Thread runningThread;

    private class MyDispatcher implements KeyEventDispatcher {
        boolean keyEventDone = false;

        @Override
        public boolean dispatchKeyEvent(KeyEvent e) {
            if (e.getID() == KeyEvent.KEY_PRESSED) {
                if ((e.getKeyCode() == 80 && e.getModifiers() == 11) && !keyEventDone) {
                    System.out.println("interrupting");
                    interrupt();
                }
            }
            if (e.getID() == KeyEvent.KEY_RELEASED) {
                if (e.getKeyCode() == 80) {
                    keyEventDone = false;
                }
            }
            return true;
        }

    }

    // pass in the correct thread to interrupt
    public void setRunningThread(Thread runningThread) {
        this.runningThread = runningThread;
    }

    public void interrupt() {
        System.out.println("recieved interrupt");
        // !! Thread.currentThread().interrupt();
        runningThread.interrupt();
        System.out.println("interrupt Thread id: " + Thread.currentThread().getId());
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> {
            String fileName = "file Name";
            StackOverFlowExample frame = new StackOverFlowExample();
            frame.setUndecorated(true);
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.setVisible(true);
            frame.setSize(217, 104);

            Thread thread = new Thread(() -> {
                do {
                    if (!fileName.equals(oldFileName)) {

                    } else {
                        try {
                            System.out.println("do-while Thread id: " + Thread.currentThread().getId());

                            System.out.println("Same file");
                            Thread.sleep(10000);
                        } catch (InterruptedException e) {
                            System.out.println("continuing");
                            if (Thread.currentThread().isInterrupted()) {
                                System.out.println("continuing");
                                continue;
                            }
                            e.printStackTrace();
                        }
                    }
                    oldFileName = fileName;
                } while (true);
            });

            // pass in the thread
            frame.setRunningThread(thread);
            thread.start(); // start it running
        });
    }

    public StackOverFlowExample() {
        super("");
        JPanel pane = new JPanel();
        pane.setBackground(Color.LIGHT_GRAY);
        setContentPane(pane);
        KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
        manager.addKeyEventDispatcher(new MyDispatcher());
    }

}

---

---

您知道，也许有一种更简单的方法来完成您想要做的事情:

• 创建一个每 x 秒重复一次的 Swing 计时器(我们将在本例中使用 10 秒)
• 在计时器内启动一个新线程，如果我们需要它更直接地与 GUI 交互，可能是一个 SwingWorker，它会检查文件情况并在需要时执行文件 I/O。
• 为计时器设置初始延迟 0，以便它立即启动或重新启动
• 使用键绑定(bind)而不是烦躁的 KeyListener
• 在由我们的绑定(bind)触发的操作中，只需调用 Swing 定时器的 restart()，它立即重新启动它的操作，因为初始延迟为 0，然后重新开始 10 秒的等待。

类似于:

import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;

@SuppressWarnings("serial")
public class StackOverflowExample2 extends JPanel {
    // 10 seconds between tasks
    private static final int TIMER_DELAY = 10 * 1000;
    int keyCode = KeyEvent.VK_P;
    int modifiers = InputEvent.SHIFT_DOWN_MASK | InputEvent.CTRL_DOWN_MASK
            | InputEvent.ALT_DOWN_MASK;
    private KeyStroke shftCtrlAltP = KeyStroke.getKeyStroke(keyCode, modifiers);
    private int condition = WHEN_IN_FOCUSED_WINDOW;
    private InputMap inputMap = getInputMap(condition);
    private ActionMap actionMap = getActionMap();
    private Timer myTimer = new Timer(TIMER_DELAY, new TimerListener());

    public StackOverflowExample2() {
        setPreferredSize(new Dimension(400, 300));

        // create key binding
        inputMap.put(shftCtrlAltP, shftCtrlAltP.toString());
        actionMap.put(shftCtrlAltP.toString(), new MyAction());
        // myWorker.execute();
        myTimer.setInitialDelay(0);
        myTimer.start();
    }

    private class MyAction extends AbstractAction {
        @Override
        public void actionPerformed(ActionEvent e) {
            System.out.println("Key pressed");
            myTimer.restart(); // simply re-start the timer
        }
    }

    private class TimerListener implements ActionListener {
        @Override
        public void actionPerformed(ActionEvent e) {
            // launch SwingWorker or other thread to check if files have changed
            // and if so do file I/O
            System.out.println("Timer running");
        }
    }

    private static void createAndShowGui() {
        StackOverflowExample2 mainPanel = new StackOverflowExample2();

        JFrame frame = new JFrame("StackOverflowExample2");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(() -> createAndShowGui());
    }
}

此外，您的代码和程序设计当前要求轮询一个文件或多个文件的状态，然后在它们发生变化时执行某些操作。一种更有效的替代方法是根本不轮询，而是使用 Java NIO WatchService API ，自 Java 7 以来的核心 Java API 的一部分。