toolbardemo.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

/*
 * ToolBarDemo.java relies on having the Java Look and Feel Graphics
 * Repository (jlfgr-1_0.jar) in the class path.  You can download it
 * from http://developer.java.sun.com/developer/techDocs/hi/repository/.
 * When running ToolBarDemo from the command line (rather than Java Web
 * Start) put jlfgr-1_0.jar in the class path using one of the following
 * commands (assuming jlfgr-1_0.jar is in a subdirectory named jars):
 *
 *   java -cp .;jars/jlfgr-1_0.jar ToolBarDemo [Microsoft Windows]
 *   java -cp .:jars/jlfgr-1_0.jar ToolBarDemo [UNIX]
 *
 * If that doesn't work, try putting quotation marks around the path:
 *
 *   java -cp ".;jars/jlfgr-1_0.jar" ToolBarDemo [UNIX shell on Win32]
 */

import javax.swing.JToolBar;
import javax.swing.JButton;
import javax.swing.ImageIcon;

import javax.swing.JFrame;
import javax.swing.JTextArea;
import javax.swing.JScrollPane;
import javax.swing.JPanel;

import java.net.URL;

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

public class ToolBarDemo extends JPanel
                         implements ActionListener {
    protected JTextArea textArea;
    protected String newline = "\n";
    static final private String PREVIOUS = "previous";
    static final private String UP = "up";
    static final private String NEXT = "next";

    public ToolBarDemo() {
        //Create the toolbar.
        JToolBar toolBar = new JToolBar();
        addButtons(toolBar);

        //Create the text area used for output.
        textArea = new JTextArea(5, 30);
        textArea.setEditable(false);
        JScrollPane scrollPane = new JScrollPane(textArea);

        //Lay out the content pane.
        setLayout(new BorderLayout());
        setPreferredSize(new Dimension(450, 150));
        add(toolBar, BorderLayout.PAGE_START);
        add(scrollPane, BorderLayout.CENTER);
    }

    protected void addButtons(JToolBar toolBar) {
        JButton button = null;

        //first button
        button = makeNavigationButton("Back24", PREVIOUS,
                                      "Back to previous something-or-other",
                                      "Previous");
        toolBar.add(button);

        //second button
        button = makeNavigationButton("Up24", UP,
                                      "Up to something-or-other",
                                      "Up");
        toolBar.add(button);

        //third button
        button = makeNavigationButton("Forward24", NEXT,
                                      "Forward to something-or-other",
                                      "Next");
        toolBar.add(button);
    }

    protected JButton makeNavigationButton(String imageName,
                                           String actionCommand,
                                           String toolTipText,
                                           String altText) {
        //Look for the image.
        String imgLocation = "toolbarButtonGraphics/navigation/"
                             + imageName
                             + ".gif";
        URL imageURL = ToolBarDemo.class.getResource(imgLocation);

        //Create and initialize the button.
        JButton button = new JButton();
        button.setActionCommand(actionCommand);
        button.setToolTipText(toolTipText);
        button.addActionListener(this);

        if (imageURL != null) {                      //image found
            button.setIcon(new ImageIcon(imageURL));
        } else {                                     //no image found
            button.setText(altText);
            System.err.println("Resource not found: "
                               + imgLocation);
        }

        return button;
    }

    public void actionPerformed(ActionEvent e) {
        String cmd = e.getActionCommand();
        String description = null;

        // Handle each button.
        if (PREVIOUS.equals(cmd)) { //first button clicked
            description = "taken you to the previous <something>.";
        } else if (UP.equals(cmd)) { // second button clicked
            description = "taken you up one level to <something>.";
        } else if (NEXT.equals(cmd)) { // third button clicked
            description = "taken you to the next <something>.";
        }

        displayResult("If this were a real app, it would have "
                        + description);
    }

    protected void displayResult(String actionDescription) {
        textArea.append(actionDescription + newline);
    }

    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("ToolBarDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setContentPane(new ToolBarDemo());

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