java - 如何异步触发JProgressBar？

Question

我在 JPanel 中有一个 JButton(swing)，如果按下它，我将在 for 循环上执行任务EDT 线程 中的列表。在此过程中，我需要更新 JProgressBar。

问题是，当我按下 JButton 时，任务是在事件调度线程 (EDT) 中执行的。所以我无法更新在主线程或 UI 线程中触发的 JProgressBar 。

现在源代码对我来说不可用，因为我完全改变了它，并尝试使用 Eclipse SWT 来实现 JProgressBar 当 Swing JButton 被触发时，它变得困惑。

现在我收到了无效线程访问错误，因为 Display 对象在单独的 UI 线程中运行。一次，仅显示 Swing JPanel 或 Eclipse SWT Shell。

我正在使用 JOptionPane 触发 JPanel。

Answer 1

异步使用SwingWorker处理JProgressBar进度，详细使用两个Swing JButton btnStart和btnStop.

我们来获取源代码-

package com.practice;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JProgressBar;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

public class ProgressExample {

    private static JFrame frame;
    private static JButton btnStart;
    private static JButton btnStop;
    private static JProgressBar progress;
    private static Integer currValue;
    private static boolean swingWorkerHelper;
    private static SwingWorker<Integer, Void> swingWorker;

    public static void main(String[] args) {
        // Scheduling Swing app for the event dispatch thread(EDT) Asynchronously
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                runSwingAsynchronousApp();
            }
        });
    }

    private static void runSwingAsynchronousApp() {
        currValue = new Integer(0);

        btnStart = new JButton("Start");
        btnStop = new JButton("Stop");

        progress = new JProgressBar();
        progress.setMinimum(0);
        progress.setMaximum(100);
        progress.setStringPainted(true);

        btnStart.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent evt) {

                if (btnStart.getText().equals("Pause")) {
                    // interrupting swingWorker method doInBackground() implicitly safely.
                    swingWorkerHelper = false;
                    btnStart.setText("Resume");
                } else {
                    if (btnStart.getText().equals("Start") || btnStart.getText().equals("Resume"))
                        btnStart.setText("Pause");

                    showProgress();
                }
            }
        });

        btnStop.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent evt) {
                // checking swingWorker Object is initialized or not
                if (swingWorker != null) {
                    // checking is swingWorker doing process in background or not
                    if (swingWorker.getState() == SwingWorker.StateValue.STARTED) {
                        btnStart.setText("Start");
                        // interrupting swingWorker method doInBackground() explicitly
                        swingWorker.cancel(true);
                        currValue = new Integer(0);
                    }
                }
            }
        });

        frame = new JFrame();
        frame.setTitle("Asynchronously trigger JProgressBar");
        frame.getContentPane().setLayout(new GridLayout(3, 2));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setBounds(400, 250, 400, 300);

        frame.getContentPane().add(btnStart);
        frame.getContentPane().add(btnStop);
        frame.getContentPane().add(progress);

        frame.setVisible(true);
    }

    private static void showProgress() {
        swingWorker = new SwingWorker<Integer, Void>() {
            @Override
            protected Integer doInBackground() throws Exception {

                if (!swingWorkerHelper)
                    swingWorkerHelper = true;

                while (currValue < progress.getMaximum() && swingWorkerHelper) {
                    try {
                        progress.setValue(++currValue);

                        if (isCancelled())
                            return currValue;

                        Thread.sleep(70);
                    } catch (InterruptedException iex) {
                        swingWorkerHelper = false;
                        System.out.println("Stop Button interrupted SwingWorker process...");
                    }
                }
                return currValue;
            }

            @Override
            public void done() {
                System.out.printf("Progress ends with value %s " + 
                (isCancelled() ? "with" : "without") + " interruption.\n", currValue);
                if (currValue >= progress.getMaximum()) {
                    btnStart.setText("Start");
                    currValue = new Integer(0);
                }
            }
        };
        swingWorker.execute();
    }

}

希望这对您有帮助。