等待多个SwingWorkers

Question

请考虑以下代码片段：

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.lang.reflect.InvocationTargetException;
import javax.swing.*;

public class TestApplet extends JApplet
{
    @Override
    public void init()
    {
        try
        {
            SwingUtilities.invokeAndWait(new Runnable()
            {
                @Override
                public void run()
                {
                    createGUI();
                }
            });
        }
        catch(InterruptedException | InvocationTargetException ex)
        {
        }
    }

    private void createGUI()
    {
        getContentPane().setLayout(new FlowLayout());
        JButton startButton = new JButton("Do work");
        startButton.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent ae)
            {
                JLabel label = new JLabel();
                new Worker(label).execute();
            }
        });
        getContentPane().add(startButton);
    }

    private class Worker extends SwingWorker<Void, Void>
    {
        JLabel label;

        public Worker(JLabel label)
        {
            this.label = label;
        }

        @Override
        protected Void doInBackground() throws Exception
        {
            // do work
            return null;
        }

        @Override
        protected void done()
        {
            getContentPane().remove(label);
            getContentPane().revalidate();
        }
    }
}

这是在小程序中添加一个标签，该标签显示了Worker线程的一些中间结果（使用发布/处理方法）。最后，标签从小程序的窗格中删除。我的问题是，如何创建多个标签，每个标签都有自己的Worker线程，并在完成标签后将其删除？

提前致谢。

更新：

我希望这可以澄清我的问题。我希望在所有工作人员都完成任务后立即删除所有标签，而不是在每个工作人员都完成之后立即删除。

更新2：

下面的代码似乎在做我所需要的。请评论我是否做对了。我感觉有什么问题。一个问题是，尽管已删除按钮右侧的标签，但它们仍然可见。setVisible（false）似乎可以解决此问题。那是这样做的方式吗？

import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.lang.reflect.InvocationTargetException;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Random;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import javax.swing.*;

public class TestApplet extends JApplet
{
    private Queue<JLabel> labels = new LinkedList<>();
    private static final Random rand = new Random();

    @Override
    public void init()
    {
        try
        {
            SwingUtilities.invokeAndWait(new Runnable()
            {
                @Override
                public void run()
                {
                    createGUI();
                }
            });
        }
        catch(InterruptedException | InvocationTargetException ex){}
    }

    private void createGUI()
    {
        getContentPane().setLayout(new FlowLayout());
        JButton startButton = new JButton("Do work");
        startButton.addActionListener(new ActionListener()
        {
            @Override
            public void actionPerformed(ActionEvent ae)
            {
                ExecutorService executor = Executors.newFixedThreadPool(10);
                for(int i = 0; i < 10; i++)
                {
                    JLabel label = new JLabel();
                    getContentPane().add(label);
                    executor.execute(new Counter(label));
                }
            }
        });
        getContentPane().add(startButton);
    }

    private class Counter extends SwingWorker<Void, Integer>
    {
        private JLabel label;

        public Counter(JLabel label)
        {
            this.label = label;
        }

        @Override
        protected Void doInBackground() throws Exception
        {
            for(int i = 1; i <= 100; i++)
            {
                publish(i);
                Thread.sleep(rand.nextInt(80));
            }

            return null;
        }

        @Override
        protected void process(List<Integer> values)
        {
            label.setText(values.get(values.size() - 1).toString());
        }

        @Override
        protected void done()
        {
            labels.add(label);

            if(labels.size() == 10)
            {
                while(!labels.isEmpty())
                    getContentPane().remove(labels.poll());

                getContentPane().revalidate();
            }
        }
    }
}

Answer 1

我打算在所有工人完成任务后一起删除所有标签。

如上所述这里，一个CountDownLatch在这方面效果很好。在下面的示例中，每个工作程序latch.countDown()在完成时调用，而Supervisor工作程序则在latch.await()所有任务完成之前阻塞。出于演示目的，Supervisor更新标签。注释中显示的批量移除在技术上是可行的，但通常没有吸引力。而是考虑一个JList或JTable。

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.util.LinkedList;
import java.util.List;
import java.util.Queue;
import java.util.Random;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import javax.swing.*;

/**
* @see https://stackoverflow.com/a/11372932/230513
* @see https://stackoverflow.com/a/3588523/230513
*/
public class WorkerLatchTest extends JApplet {

    private static final int N = 8;
    private static final Random rand = new Random();
    private Queue<JLabel> labels = new LinkedList<JLabel>();
    private JPanel panel = new JPanel(new GridLayout(0, 1));
    private JButton startButton = new JButton(new StartAction("Do work"));

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.setTitle("Test");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new WorkerLatchTest().createGUI());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    @Override
    public void init() {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                add(new WorkerLatchTest().createGUI());
            }
        });
    }

    private JPanel createGUI() {
        for (int i = 0; i < N; i++) {
            JLabel label = new JLabel("0", JLabel.CENTER);
            label.setOpaque(true);
            panel.add(label);
            labels.add(label);
        }
        panel.add(startButton);
        return panel;
    }

    private class StartAction extends AbstractAction {

        private StartAction(String name) {
            super(name);
        }

        @Override
        public void actionPerformed(ActionEvent e) {
                startButton.setEnabled(false);
                CountDownLatch latch = new CountDownLatch(N);
                ExecutorService executor = Executors.newFixedThreadPool(N);
                for (JLabel label : labels) {
                    label.setBackground(Color.white);
                    executor.execute(new Counter(label, latch));
                }
                new Supervisor(latch).execute();
        }
    }

    private class Supervisor extends SwingWorker<Void, Void> {

        CountDownLatch latch;

        public Supervisor(CountDownLatch latch) {
            this.latch = latch;
        }

        @Override
        protected Void doInBackground() throws Exception {
            latch.await();
            return null;
        }

        @Override
        protected void done() {
            for (JLabel label : labels) {
                label.setText("Fin!");
                label.setBackground(Color.lightGray);
            }
            startButton.setEnabled(true);
            //panel.removeAll(); panel.revalidate(); panel.repaint();
        }
    }

    private static class Counter extends SwingWorker<Void, Integer> {

        private JLabel label;
        CountDownLatch latch;

        public Counter(JLabel label, CountDownLatch latch) {
            this.label = label;
            this.latch = latch;
        }

        @Override
        protected Void doInBackground() throws Exception {
            int latency = rand.nextInt(42) + 10;
            for (int i = 1; i <= 100; i++) {
                publish(i);
                Thread.sleep(latency);
            }
            return null;
        }

        @Override
        protected void process(List<Integer> values) {
            label.setText(values.get(values.size() - 1).toString());
        }

        @Override
        protected void done() {
            label.setBackground(Color.green);
            latch.countDown();
        }
    }
}