如何在 Java 中与两(2)个 SwingWorker 类共享数据

问题描述

我有两个 SwingWorker 类:FileLineCounterThread 和 FileDivisionThread

I have two SwingWorker class: FileLineCounterThread and FileDivisionThread

我将执行这两个线程.当行计数线程完成时，它将结果传递给文件分割线程.

I will execute the two threads. When the lines counting thread finishes, it will pass the result to File Division thread.

我不知道如何将结果传递给启动线程.

I do not have an idea on how to pass the result to started thread.

推荐答案

SwingWorker.execute() 是 buggy 并且只会串行执行任务.使用 ExecutorService.execute() 进行并发:

SwingWorker.execute() is buggy and will only execute tasks serially. Use ExecutorService.execute() for concurrency:

import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.util.List;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.RunnableFuture;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
import javax.swing.WindowConstants;

public class MyFrame extends JFrame implements ActionListener {

    /**
     * Test Driver
     */
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                MyFrame frame = new MyFrame("Swing Concurrency Test");
                frame.setVisible(true);
            }
        });
    }

    /**
     * Thread Executor
     * (must be explicitly shutdown, see WindowAdapter below)
     */
    private final ExecutorService exec = Executors.newFixedThreadPool(2);

    /**
     * Button action
     */
    @Override
    public void actionPerformed(ActionEvent e) {
        button.setEnabled(false);
        textArea.append("
Starting both tasks...
");

        // start both tasks, pass a reference to outer task
        FileLineCounterThread counterTask = new FileLineCounterThread();
        exec.execute(counterTask);
        FileDivisionThread divisionTask = new FileDivisionThread(counterTask);
        exec.execute(divisionTask);
    }

    /**
     * Counter task
     */
    private class FileLineCounterThread extends SwingWorker<Long, String> {
        private String template = "[FileLineCounterThread] %s
";

        @Override
        protected Long doInBackground() throws Exception {
            // do some work
            publish("started...");
            Thread.sleep(10000);

            // return the result
            return 42L;
        }

        @Override
        protected void process(List<String> chunks) {
            for (String chunk : chunks) {
                textArea.append(String.format(template, chunk));
            }
        }

        @Override
        protected void done() {
            try {
                textArea.append(String.format(
                        template, "complete.  Counted: " + get()));
            }
            catch (Exception e) {
                // catch any exceptions thrown during execution
                e.printStackTrace();
            }
        }
    }

    /**
     * File Division task 
     */
    private class FileDivisionThread extends SwingWorker<String, String> {
        private RunnableFuture<Long> counterTask;
        private String template = "    [FileDivisionThread] %s
";

        public FileDivisionThread(RunnableFuture<Long> counterTask) {
            this.counterTask = counterTask;
        }

        @Override
        protected String doInBackground() throws Exception {
            // do some initial work
            publish("started...");
            Thread.sleep(2000);

            // wait for other task to complete and get result
            publish("Waiting for line counter to finish...");
            long numLines = counterTask.get(); 
            publish("Line count received: " + numLines);

            // do the rest of the work and return result
            Thread.sleep(5000);
            return "complete.";
        }

        @Override
        protected void process(List<String> chunks) {
            for (String chunk : chunks) {
                textArea.append(String.format(template, chunk));
            }
        }

        @Override
        protected void done() {
            try {
                textArea.append(String.format(template, get()));
                button.setEnabled(true);
            }
            catch (Exception e) {
                // catch any exceptions thrown during execution
                e.printStackTrace();
            }
        }
    }

    /////////////////////////
    //// GUI Boilerplate ////
    /////////////////////////

    private JScrollPane scroller = new JScrollPane();
    private JTextArea textArea = new JTextArea();
    private JButton button = new JButton("Start");

    public MyFrame(String windowTitle) {
        super(windowTitle);
        initComponents();
    }

    private void initComponents() {
        addWindowListener(new WindowAdapter() {
            @Override
            public void windowClosed(WindowEvent e) {
                exec.shutdownNow();
                System.exit(0);
            }
        });
        button = new JButton("Start");
        button.addActionListener(this);
        textArea = new JTextArea();
        textArea.setColumns(35);
        textArea.setRows(15);
        scroller.setViewportView(textArea);

        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        getContentPane().setLayout(new GridBagLayout());

        GridBagConstraints gridBagConstraints = new GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 0;
        gridBagConstraints.insets = new Insets(10, 0, 0, 0);
        getContentPane().add(button, gridBagConstraints);

        gridBagConstraints = new GridBagConstraints();
        gridBagConstraints.gridx = 0;
        gridBagConstraints.gridy = 1;
        gridBagConstraints.fill = GridBagConstraints.BOTH;
        gridBagConstraints.weightx = 1.0;
        gridBagConstraints.weighty = 1.0;
        gridBagConstraints.insets = new Insets(10, 10, 10, 10);
        getContentPane().add(scroller, gridBagConstraints);

        pack();
    }
}

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