JProgressBar 动态更改进度条颜色

Question

我正在使用Nimbus UI Defaults和JProgressBar组件。问题在于，当我想手动更改每个进度条的进度颜色时，我会通过设置JProgressBar.setUI()函数来使用BasicProgressBarUI。但这会带来更多麻烦，因为我只想更改进度条颜色，似乎我失去了jprogressbar的默认外观（边框、背景色消失）。

因此，我可以在代码初始化时设置Nimbus ProgressBar的UIDefaults，这样可以解决问题。

但我想动态地更改每个进度条的颜色。有没有其他方法可以更改JProgressBar的进度颜色？

public class ProgressGenerator extends JFrame {

    protected int minValue = 0;
    protected int maxValue = 100;
    protected int counter = 0;
    protected JProgressBar progressBar;

    public ProgressGenerator() {
        super("JProgressBar Demo");
        setSize(300, 100);

        try {
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
        } catch (ClassNotFoundException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (InstantiationException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (IllegalAccessException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        } catch (UnsupportedLookAndFeelException e1) {
            // TODO Auto-generated catch block
            e1.printStackTrace();
        }

        progressBar = new JProgressBar();
        progressBar.setMinimum(minValue);
        progressBar.setMaximum(maxValue);
        progressBar.setStringPainted(true);

        progressBar.setForeground(Color.GREEN);

        JButton start = new JButton("Start");
        start.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                Thread runner = new Thread() {
                    public void run() {
                        counter = minValue;
                        while (counter <= maxValue) {
                            Runnable runme = new Runnable() {
                                public void run() {
                                    progressBar.setValue(counter);
                                }
                            };
                            SwingUtilities.invokeLater(runme);
                            counter++;
                            try {
                                Thread.sleep(100);
                            } catch (Exception ex) {
                            }
                        }
                    }
                };
                runner.start();
            }
        });
        getContentPane().add(progressBar, BorderLayout.CENTER);
        getContentPane().add(start, BorderLayout.WEST);
        WindowListener wndCloser = new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        };
        addWindowListener(wndCloser);
        setVisible(true);
    }

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

- mbasol

---

为了更快地获得帮助，请发布一个SSCCE，这是一个简短的、可运行的、可编译的示例。否则就必须搜索，谷歌可以返回那个。 - mKorbel

请参考这个类似的问题/答案，其中展示了如何使用UIDefaults和putClientProperty来更改单个JProgressBar的颜色。 - David Kroukamp

正如@DavidKroukamp提供的答案所示，你的sscce应该包括你自定义的Painter。 - trashgod

我想通过progressBar.setForeground更改进度条的颜色 - 我想通过弹指间获得金钱 :-) 或者换句话说：如果我们采用不正确的方法，我们将无法获得预期的结果。重复trashgod - 参见@DavidKroukamp引用的QA - kleopatra

@DavidKroukamp 自定义UI大多数情况下都是错误的方法（比你期望的要更费力才能做到正确）-只有在核心UI未提供所需功能时才建议使用。据我理解，这里只是一个配置问题，可以按照其他线程中概述的方式解决。 - kleopatra

Answer 1

首先，Kelopatra获得了第一名。

以下是我制作的一个示例：

JProgressBar的颜色最初是通过以下方式设置的：

UIDefaults defaults = new UIDefaults();
defaults.put("ProgressBar[Enabled].foregroundPainter", new MyPainter(Color.GREEN));
defaults.put("ProgressBar[Enabled+Finished].foregroundPainter", new MyPainter(Color.GREEN));

progressBar.putClientProperty("Nimbus.Overrides.InheritDefaults", Boolean.TRUE);
progressBar.putClientProperty("Nimbus.Overrides", defaults);

在50%的进度时，颜色将会变成红色：

if (progressBar.getValue() == 50) {//change color on 50%
   UIDefaults defaults = new UIDefaults();
   defaults.put("ProgressBar[Enabled].foregroundPainter", new MyPainter(Color.RED));
   defaults.put("ProgressBar[Enabled+Finished].foregroundPainter", new MyPainter(Color.RED));
   progressBar.putClientProperty("Nimbus.Overrides.InheritDefaults", Boolean.TRUE);
   progressBar.putClientProperty("Nimbus.Overrides", defaults);                          
}

Test.java:

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.event.*;
import java.beans.*;
import javax.swing.*;

public class Test {

    public static void createAndShowGUI() {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        final JProgressBar progressBar = new JProgressBar();
        progressBar.setStringPainted(true);
        progressBar.setValue(0);
        progressBar.setBorderPainted(false);

        JButton startButton = new JButton("Start");

        startButton.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent ae) {
                UIDefaults defaults = new UIDefaults();
                defaults.put("ProgressBar[Enabled].foregroundPainter", new MyPainter(Color.GREEN));
                defaults.put("ProgressBar[Enabled+Finished].foregroundPainter", new MyPainter(Color.GREEN));

                progressBar.putClientProperty("Nimbus.Overrides.InheritDefaults", Boolean.TRUE);
                progressBar.putClientProperty("Nimbus.Overrides", defaults);

                SwingWorker worker = new SwingWorker() {
                    int current = 0, lengthOfTask = 100;

                    @Override
                    public Void doInBackground() {
                        while (current <= lengthOfTask && !isCancelled()) {

                            try { // dummy task
                                Thread.sleep(50);
                            } catch (InterruptedException ie) {
                            }

                            setProgress(100 * current / lengthOfTask);
                            current++;
                        }
                        return null;
                    }
                };
                worker.addPropertyChangeListener(new PropertyChangeListener() {
                    @Override
                    public void propertyChange(PropertyChangeEvent pce) {

                        String strPropertyName = pce.getPropertyName();
                        if ("progress".equals(strPropertyName)) {
                            int progress = (Integer) pce.getNewValue();
                            progressBar.setValue(progress);

                            if (progressBar.getValue() == 50) {//change color on 50%
                                UIDefaults defaults = new UIDefaults();
                                defaults.put("ProgressBar[Enabled].foregroundPainter", new MyPainter(Color.RED));
                                defaults.put("ProgressBar[Enabled+Finished].foregroundPainter", new MyPainter(Color.RED));

                                progressBar.putClientProperty("Nimbus.Overrides.InheritDefaults", Boolean.TRUE);
                                progressBar.putClientProperty("Nimbus.Overrides", defaults);
                            }

                        }
                    }
                });
                worker.execute();
            }
        });

        JPanel holder = new JPanel();
        holder.add(progressBar);
        holder.add(startButton);

        frame.add(holder);
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel("com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel");
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }
                createAndShowGUI();
            }
        });
    }
}

class MyPainter implements Painter<JProgressBar> {

    private final Color color;

    public MyPainter(Color c1) {
        this.color = c1;
    }
    @Override
    public void paint(Graphics2D gd, JProgressBar t, int width, int height) {
        gd.setColor(color);
        gd.fillRect(0, 0, width, height);
    }
}

- David Kroukamp

---

+1 动态根据数值改变颜色，非常不错的设计 :-) - kleopatra

@David Kroukamp 这是不是意味着我可以重写 JProgressBar 的 setBackground 和 setForeground 方法并应用 UI 默认值呢？ - mbasol

@DavidKroukamp 我有一个关于Painter类的问题。我想让进度条中的条形不超过边框区域。我尝试更改g.fillRect(0,0,width,height-4);它确实改变了底部，但顶部仍然超出了边框。有什么解决办法吗？ - mbasol

Answer 2

Nimbus支持每个组件的皮肤定制，这也已经在其他问题中得到了回答。对于应用于JProgressBar“bar”的情况，意味着使用自定义的foregroundPainter配置实例，如下所示：

progressBar = new JProgressBar();

UIDefaults defaults = new UIDefaults();
Painter painter = new MyPainter(Color.GREEN);
defaults.put("ProgressBar[Enabled].foregroundPainter", painter);
defaults.put("ProgressBar[Enabled+Finished].foregroundPainter", painter);

progressBar.putClientProperty("Nimbus.Overrides.InheritDefaults", Boolean.TRUE);
progressBar.putClientProperty("Nimbus.Overrides", defaults);

最简化（外观丑陋）的绘图工具可能是这样的：

public static class MyPainter extends AbstractRegionPainter {

    private Color fillColor;
    public MyPainter(Color color) {
        // as a slight visual improvement, make the color transparent
        // to at least see the background gradient
        // the default progressBarPainter does it as well (plus a bit more)
        fillColor = new Color(
                color.getRed(), color.getGreen(), color.getBlue(), 156);
    }

    @Override
    protected void doPaint(Graphics2D g, JComponent c, int width,
            int height, Object[] extendedCacheKeys) {
        g.setColor(Color.GREEN);
        g.fillRect(0, 0, width, height);
    }

    @Override
    protected PaintContext getPaintContext() {
        return null;
    }

}

为了让其外观更加美观，可以查看ProgressBarPainter：它是包私有的，所以除了理解它如何实现渐变/路径绘制并在自定义实现中做相同的事情之外，你无法做太多操作。

- kleopatra

---

+1 别忘了 "ProgressBar[Enabled+Finished].foregroundPainter"，否则在 100% 完成时会恢复为原始状态。 - David Kroukamp