外部 ProgressBar 不是运行与 Button Action Listener 并发

Question

我用 Swing worker 创建了一个外部 class，运行是进度条。这是代码，

public class ExtProgressMonitor extends JFrame {

private static final long serialVersionUID = 1L;
private static final String s = "Database Statistics Report is exectuing in the Background";
private JProgressBar progressBar = new JProgressBar(0, 100);
private JLabel label = new JLabel(s, JLabel.CENTER);

public ExtProgressMonitor() {
    this.setLayout(new GridLayout(0, 1));
    this.setTitle("Database Utility Execution");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.add(progressBar);
    this.add(label);
    this.setSize(100, 100);
    this.setLocationRelativeTo(null);
    this.setVisible(true);
    pack();
}

public void runCalc() {
    progressBar.setIndeterminate(false);
    progressBar.setStringPainted(false);
    TwoWorker task = new TwoWorker();
    task.addPropertyChangeListener(new PropertyChangeListener() {

        @Override
        public void propertyChange(PropertyChangeEvent e) {
            if ("progress".equals(e.getPropertyName())) {
                progressBar.setIndeterminate(false);
                progressBar.setValue((Integer) e.getNewValue());
            }
        }
    });
    task.execute();
}

private class TwoWorker extends SwingWorker<Integer, Integer> {

    private static final int N = 500;
    private final DecimalFormat df = new DecimalFormat(s);
    Integer x = 1;

    @Override
    protected Integer doInBackground() throws Exception {
        if (!javax.swing.SwingUtilities.isEventDispatchThread()) {
            System.out.println("javax.swing.SwingUtilities.isEventDispatchThread() + returned false.");
        }
        for (int i = 1; i <= N; i++) {
            x = x - (((x * x - 2) / (2 * x)));
            setProgress(i * (100 / N));
            publish(Integer.valueOf(x));
            Thread.sleep(1000); // simulate latency
        }
        return Integer.valueOf(x);
    }

    @Override
    protected void process(List<Integer> chunks) {
        for (Integer percent : chunks ) {
           progressBar.setValue(progressBar.getValue() + percent);
        }
    }
}

当我在 main class 中调用上面的代码时，上面的代码有效，如下所示。

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

        @Override
        public void run() {
            ExtProgress t = new ExtProgress();
            t.runCalc();
        }
    });
}

但是，当我尝试在从数据库中获取大量行的操作按钮中调用相同内容时，大约需要 15-20 分钟。 progressbar 启动，一旦 db 进程启动，progressbar 被冻结，而 db statistics fetched.once 漫长的过程结束，progress bar 继续运行再次。

private void jButton1ActionPerformed(java.awt.event.ActionEvent e) throws Exception {                                         
         
    ExtProgressMonitor t = new ExtProgressMonitor();
    t.runCalc();
    CheckStorage.DBVaultCheck(Host, port, instance, workbook, Schema_Password, schema);
    //.. Rest of the process, check storage comes from another class. 
    });

你能帮我解决这个问题吗？

Answer 1

我刚刚在您在问题中发布的代码中添加了三行（并注释掉了另外两行）。我添加的行显示在下面的代码中，前面有注释。

import java.awt.EventQueue;
import java.awt.GridLayout;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.text.DecimalFormat;
import java.util.List;

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

public class ExtProgressMonitor extends JFrame {

    private static final long serialVersionUID = 1L;
    private static final String s = "Database Statistics Report is exectuing in the Background";
    private JProgressBar progressBar = new JProgressBar(0, 100);
    private JLabel label = new JLabel(s, JLabel.CENTER);

    public ExtProgressMonitor() {
        this.setLayout(new GridLayout(0, 1, 10, 10));
        this.setTitle("Database Utility Execution");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.add(progressBar);
        this.add(label);

        /*Added next three lines.*/
        JButton b = new JButton("GO");
        b.addActionListener(e -> runCalc());
        add(b);

        pack();
//        this.setSize(100, 100);
        this.setLocationRelativeTo(null);
        this.setVisible(true);
    }

    public void runCalc() {
        progressBar.setIndeterminate(false);
        progressBar.setStringPainted(false);
        TwoWorker task = new TwoWorker();
        task.addPropertyChangeListener(new PropertyChangeListener() {

            @Override
            public void propertyChange(PropertyChangeEvent e) {
                if ("progress".equals(e.getPropertyName())) {
                    progressBar.setIndeterminate(false);
                    progressBar.setValue((Integer) e.getNewValue());
                }
            }
        });
        task.execute();
    }

    private class TwoWorker extends SwingWorker<Integer, Integer> {
        private static final int N = 500;
        private final DecimalFormat df = new DecimalFormat(s);
        Integer x = 1;

        @Override
        protected Integer doInBackground() throws Exception {
            if (!javax.swing.SwingUtilities.isEventDispatchThread()) {
                System.out.println(
                        "javax.swing.SwingUtilities.isEventDispatchThread() + returned false.");
            }
            for (int i = 1; i <= N; i++) {
                x = x - (((x * x - 2) / (2 * x)));
                setProgress(i * (100 / N));
                publish(Integer.valueOf(x));
                Thread.sleep(1000); // simulate latency
            }
            return Integer.valueOf(x);
        }

        @Override
        protected void process(List<Integer> chunks) {
            for (Integer percent : chunks) {
                progressBar.setValue(progressBar.getValue() + percent);
            }
        }
    }
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                ExtProgressMonitor t = new ExtProgressMonitor();
//                t.runCalc();
            }
        });
    }
}

当我点击 GO 按钮时，进度条开始填充。

Answer 2

代表您的应用程序的 MRE 可能如下所示：

import java.awt.GridLayout;
import java.text.DecimalFormat;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.SwingWorker;

public class SwingMain {

    SwingMain() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLocationRelativeTo(null);
        frame.add(new TestPanel());
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        new SwingMain();
    }
}

class TestPanel extends JPanel {

    public TestPanel() {

        JButton btn = new JButton("Run long process");
        btn.addActionListener(evt -> runLongProcess());
        add(btn);
    }

    private void runLongProcess() {
        new ExtProgressMonitor().runCalc();
        CheckStorage.DBVaultCheck();
    }
}

//For a second frame it is recommended to use JDialog instead of JFRame
class ExtProgressMonitor extends JFrame {

    private static final long serialVersionUID = 1L;
    private static final String s = "Database Statistics Report is exectuing in the Background";
    private final JProgressBar progressBar = new JProgressBar(0, 100);
    private final JLabel label = new JLabel(s, JLabel.CENTER);

    public ExtProgressMonitor() {
        this.setLayout(new GridLayout(0, 1));
        this.setTitle("Database Utility Execution");
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.add(progressBar);
        this.add(label);
        this.setSize(100, 100);
        this.setLocationRelativeTo(null);
        this.setVisible(true);
        pack();
    }

    public void runCalc() {
        progressBar.setIndeterminate(false);
        progressBar.setStringPainted(false);
        new TwoWorker().execute();
    }

    private class TwoWorker extends SwingWorker<Integer, Integer> {

        private static final int N = 500;
        private final DecimalFormat df = new DecimalFormat(s);
        Integer x = 1;

        @Override
        protected Integer doInBackground() throws Exception {
            for (int i = 1; i <= N; i++) {
                x = x - (x * x - 2) / (2 * x);
                publish(Integer.valueOf(x));
                Thread.sleep(1000); // simulate latency
            }
            return Integer.valueOf(x);
        }

        @Override
        protected void process(List<Integer> chunks) {
            for (Integer percent : chunks ) {
                progressBar.setValue(progressBar.getValue() + percent);
            }
        }
    }
}

class CheckStorage{

    private static final int  LIMIT = 1000;
    public static void DBVaultCheck() {
        int counter = 0;
        while(counter ++ < LIMIT)   { //simulate long process
            try {
                Thread.sleep(1000);
                System.out.println(counter);
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }
        }
    }
}

此代码的问题在于 CheckStorage.DBVaultCheck() 在 EDT 上启动了一个较长的进程。
Swing 是一个单线程库。所有绘画任务都在事件调度线程 (EDT) 中执行。运行 EDT 上的长进程（如睡眠）使该线程保持忙碌，因此它不会做其他事情比如更新gui。 gui 变得没有响应（冻结）。
假设 CheckStorage.DBVaultCheck() 不更新 gui，您所要做的就是运行通过更改代码中的一行在不同线程上的长过程：

    private void runLongProcess() {
        new ExtProgressMonitor().runCalc();
        new Thread(()->CheckStorage.DBVaultCheck()).start();
    }

万一 CheckStorage.DBVaultCheck() 确实更新了图形用户界面，您必须采取措施确保这些更新发生在 EDT 上。 Swing gui 更新只能由 EDT 完成。

外部 ProgressBar 不是运行与 Button Action Listener 并发

External ProgressBar is not running in concurrent with Button Action Listener

java

swing

swingworker

jprogressbar

外部 ProgressBar 不是 运行 与 Button Action Listener 并发

External ProgressBar is not running in concurrent with Button Action Listener

java

swing

swingworker

jprogressbar

外部 ProgressBar 不是运行与 Button Action Listener 并发