layeredpanedemo.java

这是一个英文版的《Java程序设计与问题解决》现在好多大学都当成教材

import javax.swing.*;
import javax.swing.border.*;
import javax.accessibility.*;

import java.awt.*;
import java.awt.event.*;

/* LayeredPaneDemo.java requires images/dukeWaveRed.gif. */
public class LayeredPaneDemo extends JPanel {
    private String[] layerStrings = { "Yellow (0)", "Magenta (1)",
                                      "Cyan (2)",   "Red (3)",
                                      "Green (4)" };
    private Color[] layerColors = { Color.yellow, Color.magenta,
                                    Color.cyan,   Color.red,
                                    Color.green };

    private JLayeredPane layeredPane;
    private JLabel dukeLabel;

    public LayeredPaneDemo()    {
        //Create and load the duke icon.
        final ImageIcon icon = createImageIcon("images/dukeWaveRed.gif");

        //Create and set up the layered pane.
        layeredPane = new JLayeredPane();
        layeredPane.setPreferredSize(new Dimension(300, 310));
        layeredPane.setBorder(BorderFactory.createTitledBorder(
                                    "Move the Mouse to Move Duke"));
        layeredPane.addMouseMotionListener(new MouseMotionAdapter() {
            final int XFUDGE = 40;
            final int YFUDGE = 57;
            public void mouseEntered(MouseEvent e) {
                dukeLabel.setLocation(e.getX()-XFUDGE, e.getY()-YFUDGE);
            }
            public void mouseMoved(MouseEvent e) {
                dukeLabel.setLocation(e.getX()-XFUDGE, e.getY()-YFUDGE);
            }
        });

        //This is the origin of the first label added.
        Point origin = new Point(10, 20);

        //This is the offset for computing the origin for the next label.
        int offset = 35;

        //Add several overlapping, colored labels to the layered pane
        //using absolute positioning/sizing.
        for (int i = 0; i < layerStrings.length; i++) {
            JLabel label = createColoredLabel(layerStrings[i],
                                              layerColors[i], origin);
            layeredPane.add(label, new Integer(i));
            origin.x += offset;
            origin.y += offset;
        }

        //Create and add the Duke label to the layered pane.
        dukeLabel = new JLabel(icon);
        if (icon != null) {
            dukeLabel.setBounds(15, 225,
                                icon.getIconWidth(),
                                icon.getIconHeight());
        } else {
            System.err.println("Duke icon not found; using black square instead.");
            dukeLabel.setBounds(15, 225, 30, 30);
            dukeLabel.setOpaque(true);
            dukeLabel.setBackground(Color.BLACK);
        }
        layeredPane.add(dukeLabel, new Integer(2), 0);

        //Add control pane and layered pane to this JPanel.
        setLayout(new BoxLayout(this, BoxLayout.Y_AXIS));
        add(Box.createRigidArea(new Dimension(0, 10)));
        add(createControlPanel());
        add(Box.createRigidArea(new Dimension(0, 10)));
        add(layeredPane);
    }

    /** Returns an ImageIcon, or null if the path was invalid. */
    protected static ImageIcon createImageIcon(String path) {
        java.net.URL imgURL = LayeredPaneDemo.class.getResource(path);
        if (imgURL != null) {
            return new ImageIcon(imgURL);
        } else {
            System.err.println("Couldn't find file: " + path);
            return null;
        }
    }

    //Create and set up a colored label.
    private JLabel createColoredLabel(String text,
                                      Color color,
                                      Point origin) {
        JLabel label = new JLabel(text);
        label.setVerticalAlignment(JLabel.TOP);
        label.setHorizontalAlignment(JLabel.CENTER);
        label.setOpaque(true);
        label.setBackground(color);
        label.setForeground(Color.black);
        label.setBorder(BorderFactory.createLineBorder(Color.black));
        label.setBounds(origin.x, origin.y, 140, 140);
        return label;
    }

    //Create the control pane for the top of the frame.
    private JPanel createControlPanel() {
        final JCheckBox onTop = new JCheckBox("Top Position in Layer");
        onTop.setSelected(true);
        onTop.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                if (onTop.isSelected())
                    layeredPane.moveToFront(dukeLabel);
                else
                    layeredPane.moveToBack(dukeLabel);
            }
        });

        final JComboBox layerList = new JComboBox(layerStrings);
        layerList.setSelectedIndex(2);    //cyan layer
        layerList.addActionListener(new ActionListener () {
            public void actionPerformed(ActionEvent e) {
                int position = onTop.isSelected() ? 0 : 1;
                layeredPane.setLayer(dukeLabel,
                                     layerList.getSelectedIndex(),
                                     position);
            }
        });

        JPanel controls = new JPanel();
        controls.add(layerList);
        controls.add(onTop);
        controls.setBorder(BorderFactory.createTitledBorder(
                                 "Choose Duke's Layer and Position"));
        return controls;
    }

    public static void main(String[] args) {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("LayeredPaneDemo");
        frame.setContentPane(new LayeredPaneDemo());
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }
}