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带线程的进度条(Java Swing)

thread-sleep swing java

obohovyk · 技术社区 · 12 年前

这里有一个小例子:

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        int x = 0;
        while (jProgressBar1.getValue() < 100) {
            try {
                Thread.sleep(50);
                x++;
                jProgressBar1.setValue(x);
                jProgressBar1.repaint();
            } catch (InterruptedException ex) {
                Logger.getLogger(MainWindow.class.getName()).log(Level.SEVERE, null, ex);
            }
            System.out.println(jProgressBar1.getValue());
        }
    }

System.out.println(jProgressBar1.getValue()); 返回IDE输出的数字,但jProgressBar1不绘制此值。这个代码有什么问题?请帮忙。

2 回复 | 直到 12 年前

Sergiy Medvynskyy 12 年前

千万不要在Swing线程中使用Thread.sleep()。请改用javax.swing.Timer。

例子:

private void jButton1ActionPerformed(ActionEvent evt) {                                         
    final Timer t = new Timer(50, new ActionListener() {
        public void actionPerformed(ActionEvent e) {
            jProgressBar1.setValue(jProgressBar1.getValue() + 1);
            if (jProgressBar1.getValue() == 100) {
              ((Timer) e.getSource()).stop();
            }
        }
    });
    t.start();
}

-1

Mshnik 12 年前

问题是你在打电话 .repaint() 在同一个线程中,你正在做你的“工作”(thread.sleep)。 "repaint() does not invoke paint() directly. It schedules a call to an intermediate method, update(). Finally, update() calls paint()..." 。这意味着你正在安排一堆 repaint() 呼叫,但它们未被处理。我还打赌,一旦值达到100,进度条就会跳到满,这是因为主线程已经结束 重新绘制() 呼叫终于被处理了。

为了使jProgressBars正常工作,您必须让它们的重新绘制发生在与您正在工作的线程不同的线程中(这显然也应该发生在不同的线程-这对于大多数Swing更新也是如此)。在调用代码之前,请尝试在新线程中启动此Runnable:

public class ProgressBarPainter implements Runnable{
    public JProgressBar jProgressBar1;
    public void run(){
        while(true){
            try {
                Thread.sleep(50);
                jProgressBar1.repaint();
            } catch (InterruptedException ex) {
               break;
            }
        }
    }
}

实例运转使用上述内容的代码:

public class Frame extends JFrame {

    private static final long serialVersionUID = 1L;
    private JProgressBar bar;

    public Frame(){
        JPanel contentPanel = (JPanel) getContentPane();

        JButton b = new JButton("Do Process");
        b.addActionListener(new ActionListener(){

            @Override
            public void actionPerformed(ActionEvent e) {
                ProgressBarPainter p = new ProgressBarPainter();
                p.jProgressBar1 = bar; //Fill in with the bar you want painted
                Thread t = new Thread(p);
                t.start();

                Worker w = new Worker();
                w.jProgressBar1 = bar;
                Thread t2 = new Thread(w);
                t2.start();
            }

        });
        contentPanel.add(b, BorderLayout.SOUTH);

        bar = new JProgressBar();
        contentPanel.add(bar, BorderLayout.CENTER);

        pack();
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setVisible(true);
    }

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

}

class Worker implements Runnable{
    public JProgressBar jProgressBar1;
    public void run(){
        int x = 0;
        while(jProgressBar1.getValue() != jProgressBar1.getMaximum()){
            try {
                //Do some work
                Thread.sleep(50);
                //Update bar
                jProgressBar1.setValue(x++);
            } catch (InterruptedException ex) {
               break;
            }
        }
    }
}

class ProgressBarPainter implements Runnable{
    public JProgressBar jProgressBar1;
    public void run(){
        while(true){
            try {
                Thread.sleep(50);
                jProgressBar1.repaint();
            } catch (InterruptedException ex) {
               break;
            }
        }
    }
}