在以下应用程序中,我放置了一个按钮,单击该按钮可显示GlassPane,然后启动一个线程以更新进度条值。以下是代码:-
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.LinearGradientPaint;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class GlassPaneDownload extends JFrame implements Runnable{
Thread t;
CustomGlassPane jp;
public static void main(String args[])
{
SwingUtilities.invokeLater(new Runnable(){public void run(){new GlassPaneDownload();}});
}
public GlassPaneDownload(){
super("Glass Pane Download Simulation");
setSize(400,400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLayout(new FlowLayout());
jp=new CustomGlassPane();
jp.setOpaque(false);
setGlassPane(jp);
JButton btn=new JButton("Click Here");
btn.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent e){
//Make Glass Pane visible
jp.setVisible(true);
//Start Thread to update Progress Bar
t=new Thread();
t.start();
}});
add(btn);
setVisible(true);
}
public void run(){
for(int i=1;i<=100;i++)
{
jp.setProgress(i);
try {
Thread.sleep(100);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
t=null;
}
}
class CustomGlassPane extends JComponent
{
private final float pattern[]=new float[]{0.0f,0.499f,0.50f,1.0f};
private final Color color[]=new Color[]{Color.WHITE,Color.GRAY,Color.BLACK,Color.LIGHT_GRAY};
private int progress,oldProgress;
public void paintComponent(Graphics g1)
{
super.paintComponent(g1);
g1.setColor(new Color(1.0f,1.0f,1.0f,0.7f));
g1.fillRect(0, 0, getWidth(), getHeight());
g1.setColor(new Color(200,200,255));
g1.drawRect(100,100,200,20);
LinearGradientPaint p=new LinearGradientPaint(100,100,200,20,pattern,color);
Graphics2D g2=(Graphics2D)g1;
g2.setPaint(p);
g2.fillRect(100, 100,progress*2, 20);
}
public void setProgress(int prog)
{
progress=prog;
repaint(100,100,200,20);
//repaint();
}
}
但是,尽管GlassPane可见,但是ProgressBar并未更新。
需要帮助的朋友。
最佳答案
这是一个经典的错误:您正在通过Thread.sleep()
循环来阻塞EDT(事件调度线程)。 EDT调度所有GUI事件:绘画事件,鼠标事件,键事件,动作事件等...由于您在EDT中循环和休眠(在ActionEvent期间),因此它会阻止显示刷新(我敢打赌)单击按钮后,GUI将变得无响应)。所以
规则1:请勿阻止EDT
规则2:请勿阻止EDT,这会直接导致
规则3:请勿在EDT中添加sleep()
,并且
规则4:不要在EDT中进行任何长时间的操作
要变通解决此问题,请使用SwingWorker
或javax.swing.Timer
。这也可以与传统的Thread
和Executors
(线程池)一起使用,但是您必须确保所有修改GUI的尝试都在EDT中执行。
您可能想看一下this example,它显示了如何组合JProgressBar和SwingWorker
关于java - 线程未更新GlassPane上的进度栏,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/14139298/