java – 如何在组件绘制时创建“请等待”Swing对话框

对于Swing来说仍然相对较新,但经过几个小时的搜索,我无法在网上找到答案,因此这篇文章(对不起,如果已经回答,我忽略了它).

我在Swing应用程序中使用JFreeChart.有些图表相对较重(180k数据点),JFreeChart的ChartPanel需要约6秒才能完成第一个paintComponent().

因此,我想在组件绘制时在对话框中显示“请稍候”消息(无需显示SwingWorker的进度).我试图覆盖paintComponent方法,但不幸的是,消息永远不会出现在屏幕上(我想线程直接进入绘制图表,没有花时间绘制对话框).

我的代码看起来像这样:

public class CustomizedChartPanel extends ChartPanel{

private static final long serialVersionUID = 1L;
private JDialog dialog = null;
boolean isPainted = false;

public CustomizedChartPanel(JFreeChart chart) { super(chart); }

@Override
public void paintComponent(Graphics g) {
    //At first paint (which can be lengthy for large charts), show "please wait" message
    if (! isPainted){
        dialog = new JDialog();
        dialog.setUndecorated(true);
        JPanel panel = new JPanel();
        panel.add(new JLabel("Please wait"));
        dialog.add(panel);
        dialog.pack();
        GuiHelper.centerDialog(dialog); //Custom code to center the dialog on the screen
        dialog.setVisible(true);
        dialog.repaint();
    }

    super.paintComponent(g);

    if (! isPainted){
        isPainted = true;
        dialog.dispose();
            super.repaint();
        }
}
}

任何关于如何解决这个/最佳实践的指针将非常感谢!

谢谢,
托马斯

更新:

感谢提示&辩论:非常有帮助.

我开始使用invokeLater()实现建议的解决方案,因为我担心JLayer解决方案不起作用,因为它也在EDT上运行.

不幸的是,当invokeLater()调用paintComponent()时,我有一个空指针异常.

我的代码看起来像这样:

    @Override
public void paintComponent(Graphics graph) {
    //At first paint (which can be lengthy for large charts), show "please wait" message
    if (! isPainted){
        isPainted = true;
        dialog = new JDialog();
        dialog.setUndecorated(true);
        JPanel panel = new JPanel();
        panel.add(new JLabel("Please wait"));
        panel.add(new JLabel("Please wait !!!!!!!!!!!!!!!!!!!!!!!!!!!!!"));
        dialog.add(panel);
        dialog.pack();
        GuiHelper.centerDialog(dialog); //Custom code to center the dialog on the screen
        dialog.setVisible(true);
        dialog.repaint();
        RunnableRepaintCaller r = new RunnableRepaintCaller(this, graph, dialog);
        SwingUtilities.invokeLater(r);
    }
    else super.paintComponent(graph); //NULL POINTER EXCEPTION HERE (invoked by runnable class)
}

而runnable类是:

public class RunnableRepaintCaller implements Runnable{
private ChartPanel target;
private Graphics g;
private JDialog dialog;

public RunnableRepaintCaller(ChartPanel target, Graphics g, JDialog dialog){
    this.target = target;
    this.g = g;
    this.dialog = dialog;
}

@Override
public void run() {
    System.out.println(g);
    target.paintComponent(g);
    dialog.dispose();
}
}

再次,任何指针将非常感激!

托马斯

最佳答案
这是一个示例和/但它使用SwingWorker.你应该认真考虑使用它,因为如果操作系统以某种方式使你的帧无效并且你的JFreeChart的加载是在EDT(事件调度线程)上完成的,那么你的GUI将会被冻结.

它还允许您在处理数据时提供更好的用户反馈. (对不起,如果代码有点长,但大多数有趣的代码都在initUI和SwingWorker中).

注意:您可以使用JLayer(如果使用Java 7)而不是对话框,但在我的示例中这是不必要的.

该代码受到http://www.vogella.com/articles/JFreeChart/article.html的启发

/**
 * This code was directly taken from: http://www.vogella.com/articles/JFreeChart/article.html
 * All credits goes to him for this code.
 * 
 * Thanks to him.
 */

import java.util.List;

import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;

import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.chart.plot.PiePlot3D;
import org.jfree.data.general.DefaultPieDataset;
import org.jfree.data.general.PieDataset;
import org.jfree.util.Rotation;

public class PieChart extends JFrame {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                initUI();
            }
        });
    }

    protected static void initUI() {
        // First we create the frame and make it visible
        final PieChart demo = new PieChart("Comparison");
        demo.setSize(500, 270);
        demo.setVisible(true);
        // Then we display the dialog on that frame
        final JDialog dialog = new JDialog(demo);
        dialog.setUndecorated(true);
        JPanel panel = new JPanel();
        final JLabel label = new JLabel("Please wait...");
        panel.add(label);
        dialog.add(panel);
        dialog.pack();
        // Public method to center the dialog after calling pack()
        dialog.setLocationRelativeTo(demo);

        // allowing the frame and the dialog to be displayed and, later, refreshed
        SwingWorker<JFreeChart, String> worker = new SwingWorker<JFreeChart, String>() {

            @Override
            protected JFreeChart doInBackground() throws Exception {
                publish("Loading dataset");
                // simulating the loading of the Dataset
                try {
                    System.out.println("Loading dataset");
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                // This will create the dataset 
                PieDataset dataset = demo.createDataset();
                publish("Loading JFreeChart");
                // simulating the loading of the JFreeChart
                try {
                    System.out.println("Loading JFreeChart");
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                // based on the dataset we create the chart
                JFreeChart chart = demo.createChart(dataset, "Which operating system are you using?");
                // we put the chart into a panel
                return chart;
            }

            @Override
            protected void process(List<String> chunks) {
                label.setText(chunks.get(0));
                dialog.pack();
                dialog.setLocationRelativeTo(demo);
                dialog.repaint();
            }

            @Override
            protected void done() {
                try {
                    // Retrieve the created chart and put it in a ChartPanel
                    ChartPanel chartPanel = new ChartPanel(this.get());
                    // add it to our frame
                    demo.setContentPane(chartPanel);
                    // Dispose the dialog.
                    dialog.dispose();
                    // We revalidate to trigger the layout
                    demo.revalidate();
                    // Repaint, just to be sure
                    demo.repaint();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }

        };
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                     worker.execute();
            }
        });
        dialog.setVisible(true);
    }

    public PieChart(String applicationTitle) {
        super(applicationTitle);
    }

    /** * Creates a sample dataset */

    private PieDataset createDataset() {
        DefaultPieDataset result = new DefaultPieDataset();
        result.setValue("Linux", 29);
        result.setValue("Mac", 20);
        result.setValue("Windows", 51);
        return result;

    }

    /** * Creates a chart */

    private JFreeChart createChart(PieDataset dataset, String title) {

        JFreeChart chart = ChartFactory.createPieChart3D(title, // chart title
                dataset, // data
                true, // include legend
                true, false);
        PiePlot3D plot = (PiePlot3D) chart.getPlot();
        plot.setStartAngle(290);
        plot.setDirection(Rotation.CLOCKWISE);
        plot.setForegroundAlpha(0.5f);
        return chart;

    }

}

转载注明原文:java – 如何在组件绘制时创建“请等待”Swing对话框 - 代码日志