Java Swing循环进度条无法正常工作 [英] Circular Progress Bar for Java Swing not working

问题描述

我在Oracle网站上发现了这个测试项目，因为我想要在我的项目中添加循环进度条。

i've discovered this test project from Oracle site because i want to add a circular progress bar in my project.

我正在使用Netbeans开发应用程序，当我启动应用程序时，应该是圆圈的JPanel .. ..令人失望。

I'm developing the application with Netbeans, and when i start the application, the JPanel where the circle should be.... disappaer.

我删除了所有无法解决此问题的代码，我已经得到了这段代码：

I've removed all the code that is not useful to solve this problem and i've got this code:

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.beans.PropertyChangeEvent;
import javax.swing.*;
import javax.swing.plaf.LayerUI;


public class Loading_Test extends javax.swing.JFrame
{
    static final WaitLayerUI layerUI = new WaitLayerUI();
    public Loading_Test()
    {

        JPanel panel = new JPanel();
        JLayer<JPanel> jlayer = new JLayer<>(panel, layerUI);
        add(jlayer);

        initComponents();
    }

    @SuppressWarnings("unchecked")
    private void initComponents() {

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 400, Short.MAX_VALUE)
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGap(0, 300, Short.MAX_VALUE)
        );

        pack();
    }

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

            @Override
            public void run()
            {                
                JFrame frame = new Loading_Test();
                frame.setVisible(true);
                layerUI.start();
            }
        });
    }
}
class WaitLayerUI extends LayerUI<JPanel> implements ActionListener
{

    private boolean mIsRunning;
    private boolean mIsFadingOut;
    private Timer mTimer;
    private int mAngle;
    private int mFadeCount;
    private int mFadeLimit = 15;

    @Override
    public void paint(Graphics g, JComponent c)
    {
        int w = c.getWidth();
        int h = c.getHeight();

        // Paint the view.
        super.paint(g, c);

        if (!mIsRunning)
        {
            return;
        }

        Graphics2D g2 = (Graphics2D) g.create();

        float fade = (float) mFadeCount / (float) mFadeLimit;
        // Gray it out.
        Composite urComposite = g2.getComposite();
        g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .5f * fade));
        g2.fillRect(0, 0, w, h);
        g2.setComposite(urComposite);

        // Paint the wait indicator.
        int s = Math.min(w, h) / 5;
        int cx = w / 2;
        int cy = h / 2;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setStroke(new BasicStroke(s / 4, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
        g2.setPaint(Color.white);
        g2.rotate(Math.PI * mAngle / 180, cx, cy);
        for (int i = 0; i < 12; i++)
        {
            float scale = (11.0f - (float) i) / 11.0f;
            g2.drawLine(cx + s, cy, cx + s * 2, cy);
            g2.rotate(-Math.PI / 6, cx, cy);
            g2.setComposite(AlphaComposite.getInstance(
                    AlphaComposite.SRC_OVER, scale * fade));
        }

        g2.dispose();
    }

    @Override
    public void actionPerformed(ActionEvent e)
    {
        if (mIsRunning)
        {
            firePropertyChange("tick", 0, 1);
            mAngle += 3;
            if (mAngle >= 360)
            {
                mAngle = 0;
            }
            if (mIsFadingOut)
            {
                if (--mFadeCount == 0)
                {
                    mIsRunning = false;
                    mTimer.stop();
                }
            }
            else if (mFadeCount < mFadeLimit)
            {
                mFadeCount++;
            }
        }
    }

    public void start()
    {
        if (mIsRunning)
        {
            return;
        }

        // Run a thread for animation.
        mIsRunning = true;
        mIsFadingOut = false;
        mFadeCount = 0;
        int fps = 24;
        int tick = 1000 / fps;
        mTimer = new Timer(tick, this);
        mTimer.start();
    }

    public void stop()
    {
        mIsFadingOut = true;
    }

    @Override
    public void applyPropertyChange(PropertyChangeEvent pce, JLayer l)
    {
        if ("tick".equals(pce.getPropertyName()))
        {
            l.repaint();
        }
    }
}

如果您运行此代码就像，你应该有同样的问题，JPanel没有显示。

If you run this code "as is", you should have the same my problem, the JPanel is not shown.

但我发现如果我删除与布局相关的行（27~36），进度条就会开始工作。

But i've discovered that if i remove the layout-related lines (27~36) the progress bar starts to work.

您还必须手动设置窗口大小添加

You also have to set manually the windows size adding

setSize(300, 300);

pack();

因为布局线是由Netbeans自动生成的，所以我试图了解如何解决这个问题问题，因为这些特定的代码行被Netbeans编辑器阻止编辑。

Because the layout-lines are automatically generated by Netbeans, i'm trying to understand how to solve this problem, because this particular lines of code are blocked for editing by Netbeans Editor.

推荐答案

找到一个更好的简单（和工作）解决方案通过 SwingLabs 进行Swing组件扩展

Found a better simple (and working) solution with Swing Components Extension by SwingLabs

JXBusyLabel

它的编辑器有一个完全集成的NetBeans插件，所以使用非常简单

There is a fully integrating plugin with NetBeans for its editor, so is very simple to use

这篇关于Java Swing循环进度条无法正常工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！