mousewheeleventdemo.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

/*
 * MouseWheelEventDemo.java is a 1.4 example
 * that requires the following file:
 *   BlankArea.java 
 */

import javax.swing.*;

import java.awt.GridBagLayout;
import java.awt.GridBagConstraints;
import java.awt.Insets;
import java.awt.Color;
import java.awt.Dimension;

import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

public class MouseWheelEventDemo extends JApplet 
                            implements MouseWheelListener {
    BlankArea blankArea;
    JTextArea textArea;
    final static String newline = "\n";

    public void init() {
        GridBagLayout gridbag = new GridBagLayout();
        GridBagConstraints c = new GridBagConstraints();
        JPanel contentPane = new JPanel();
        contentPane.setLayout(gridbag);

        c.fill = GridBagConstraints.BOTH;
        c.gridwidth = GridBagConstraints.REMAINDER;
        c.weightx = 1.0;
        c.weighty = 1.0;

        c.insets = new Insets(1, 1, 1, 1);
        blankArea = new BlankArea(new Color(0.98f, 0.97f, 0.85f));
        gridbag.setConstraints(blankArea, c);
        contentPane.add(blankArea);

        c.insets = new Insets(0, 0, 0, 0);
        textArea = new JTextArea();
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);
        scrollPane.setVerticalScrollBarPolicy(
                JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setPreferredSize(new Dimension(200, 75));
        gridbag.setConstraints(scrollPane, c);
        contentPane.add(scrollPane);

        //Register for mouse events on blankArea and applet.
        blankArea.addMouseWheelListener(this);
        addMouseWheelListener(this);

        setContentPane(contentPane);
    }

    public void mouseWheelMoved(MouseWheelEvent e) {
       saySomething("Mouse wheel moved (# of clicks: "
                    + e.getWheelRotation() + ")", e);
    }

    void saySomething(String eventDescription, MouseWheelEvent e) {
        textArea.append(eventDescription + " detected on "
                        + e.getComponent().getClass().getName()
                        + "." + newline);
    }
}