对于Swing来说还是比较新的，但经过几个小时的搜索后，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，我希望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，而不花时间绘制对话框）。
我的代码如下所示：
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();
}
}
}
非常感谢任何关于如何解决这个/最佳实践的指针！
谢谢， 托马斯
更新：
感谢提示＆amp;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解决方案无法运行，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。
我的代码如下所示：
@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)
}
可运行的类是：
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();
}
}
同样，任何指针都会非常感激！
托马斯
答案 0 :(得分：5)
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OS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，但在我的示例中这不是必需的。
该代码受到http://www.vogella.com/articles/JFreeChart/article.html
的高度启发/**
* 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;
}
}
答案 1 :(得分：2)
您可以按照here的说明使用JLayer。
这是专门针对忙碌指标的。
您可以将JPanel与setEnabled(false)保持一致，直到数据完全加载为止。这可以防止对JPanel进行不必要的点击。
答案 2 :(得分：0)
自从我用Java做过任何事以来已经很长时间了，但据我所知，repaint()方法实际上并没有导致任何绘图发生。它只是将控件标记为需要在尽可能快的机会重绘。如果要立即绘制组件，则需要直接调用paint()方法。
答案 3 :(得分：-2)
您需要在新线程中启动等待对话框。我不知道你是如何创建图表的，但这里有一个样本
SwingUtilities.invokeLater(new Runnable() {
public void run() {
dialog = new JDialog();
dialog.setUndecorated(true);
JPanel panel = new JPanel();
panel.add(new JLabel("Please wait"));
dialog.add(panel);
GuiHelper.centerDialog(dialog);
dialog.setVisible(true);
Thread performer = new Thread(new Runnable() {
public void run() {
dialog.setVisible(false);
//Here the code that prepare the chart
}
});
performer.start();
}
});