java - Java Swing 的循环进度条不起作用

Question

我从 Oracle 站点发现了这个测试项目，因为我想在我的项目中添加一个圆形进度条。

我正在使用 Netbeans 开发应用程序，当我启动应用程序时，圆圈应该在的 JPanel.... disappaer。

我已经删除了所有对解决这个问题没有用的代码，我得到了这个代码：

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“按原样”运行此代码，您应该遇到与我相同的问题，JPanel 未显示。

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。

您还必须手动设置窗口大小添加

setSize(300, 300);

后

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，因为 Netbeans 编辑器阻止了这些特定的代码行进行编辑。

score 4 · Accepted Answer

I've lost one day and it still not working.... I'll use an animated gif on JLabel.... End of story!

@Robin has important info, and seems like as you limited by usage of GuiBulder..., then I'm don't want to comment something, result is

enter image description here

from little bit modified 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 {

    static final WaitLayerUI layerUI = new WaitLayerUI();
    JFrame frame = new JFrame("JLayer With Animated Gif");

    public Loading_Test() {
        JPanel panel = new JPanel() {

            @Override
            public Dimension getPreferredSize() {
                return new Dimension(400, 300);
            }
        };
        JLayer<JPanel> jlayer = new JLayer<>(panel, layerUI);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.add(jlayer);
        frame.pack();
        frame.setVisible(true);
        layerUI.start();
    }

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

            @Override
            public void run() {
                Loading_Test loading_Test = new Loading_Test();

            }
        });
    }
}

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();
        super.paint(g, c); // Paint the view.
        if (!mIsRunning) {
            return;
        }
        Graphics2D g2 = (Graphics2D) g.create();
        float fade = (float) mFadeCount / (float) mFadeLimit;
        Composite urComposite = g2.getComposite(); // Gray it out.
        g2.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, .5f * fade));
        g2.fillRect(0, 0, w, h);
        g2.setComposite(urComposite);
        int s = Math.min(w, h) / 5;// Paint the wait indicator.
        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;
        }
        mIsRunning = true;// Run a thread for animation.
        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();
        }
    }
}

have to add two JButtons, one for start and second for stop (show and hide animated Gig)
don't forger that JPanel has implemented FlowLayout, that pretty accepting PreferredSize came from its childs,

score 4 · Accepted Answer

使用SwingLabs的 Swing Components Extension 找到更好的简单（且有效）解决方案

JXBusyLabel

它的编辑器有一个与 NetBeans 完全集成的插件，因此使用起来非常简单

score 1 · Accepted Answer

从您的问题和评论看来，您JLayer在 Netbeans 中实施时遇到了问题，我建议您宁愿选择一个CardLayout允许您在 normalJPanel和带有spinner之间切换的方法。

这是一个简单的教程：CardLayout With Netbeans

java - Java Swing 的循环进度条不起作用

3 回答 3

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