Java 中文官方教程 2022 版（十五）（1）

public void init() {
    //Execute a job on the event-dispatching thread:
    //creating this applet's GUI.
    try {
        javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
                createGUI();
            }
        });
    } catch (Exception e) {
        System.err.println("createGUI didn't successfully complete");
    }
}
private void createGUI() {
    JLabel label = new JLabel(
                       "You are successfully running a Swing applet!");
    label.setHorizontalAlignment(JLabel.CENTER);
    label.setBorder(BorderFactory.createMatteBorder(1,1,1,1,Color.black));
    getContentPane().add(label, BorderLayout.CENTER);
}

private void createGUI() {
    ...
    animator = new Animator();
    animator.setOpaque(true);
    animator.setBackground(Color.white);
    setContentPane(animator);
    ...
}
public void init() {
    loadAppletParameters();
    //Execute a job on the event-dispatching thread:
    //creating this applet's GUI.
    try {
        javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
                createGUI();
            }
        });
    } catch (Exception e) { 
        System.err.println("createGUI didn't successfully complete");
    }
    //Set up the timer that will perform the animation.
    timer = new javax.swing.Timer(speed, this);
    timer.setInitialDelay(pause);
    timer.setCoalesce(false);
    timer.start(); //Start the animation.
    //Background task for loading images.
    SwingWorker worker = (new SwingWorker<ImageIcon[], Object>() {
            public ImageIcon[] doInBackground() {
                final ImageIcon[] innerImgs = new ImageIcon[nimgs];
            *...//Load all the images...*
            return imgs;
        }
        public void done() {
            //Remove the "Loading images" label.
            animator.removeAll();
            loopslot = -1;
            try {
                imgs = get();
            } *...//Handle possible exceptions*
        }
    }).execute();
}

public void init() {
    ...
    imgs = new ImageIcon[nimgs];
    (new SwingWorker<ImageIcon[], Object>() {
        public ImageIcon[] doInBackground() {
            //Images are numbered 1 to nimgs,
            //but fill array from 0 to nimgs-1.
            for (int i = 0; i < nimgs; i++) {
                imgs[i] = loadImage(i+1);
            }
            return imgs;
        }
        ...
    }).execute();
}
...
protected ImageIcon loadImage(int imageNum) {
    String path = dir + "/T" + imageNum + ".gif";
    int MAX_IMAGE_SIZE = 2400;  //Change this to the size of
                                 //your biggest image, in bytes.
    int count = 0;
    BufferedInputStream imgStream = new BufferedInputStream(
       this.getClass().getResourceAsStream(path));
    if (imgStream != null) {
        byte buf[] = new byte[MAX_IMAGE_SIZE];
        try {
            count = imgStream.read(buf);
            imgStream.close();
        } catch (java.io.IOException ioe) {
            System.err.println("Couldn't read stream from file: " + path);
            return null;
        }
        if (count <= 0) {
            System.err.println("Empty file: " + path);
            return null;
        }
        return new ImageIcon(Toolkit.getDefaultToolkit().createImage(buf));
    } else {
        System.err.println("Couldn't find file: " + path);
        return null;
    }
}

<script src="https://www.java.com/js/deployJava.js" type="text/javascript">
</script><script type="text/javascript">
//<![CDATA[
    var attributes = { archive: 'https://docs.oracle.com/javase/tutorialJWS/samples/uiswing/TumbleItemProject/TumbleItem.jar',
                       codebase: 'https://docs.oracle.com/javase/tutorialJWS/samples/uiswing/TumbleItemProject',
                       code:'components.TumbleItem', width:'600', height:'95' };
    var parameters = { permissions:'sandbox', nimgs:'17', offset:'-57',
                       img: 'images/tumble', maxwidth:'120' };
    deployJava.runApplet(attributes, parameters, '1.7');
//]]>
</script><noscript>A browser with Javascript enabled is required for this page to operate properly.</noscript>

*//In initialization code:*
    ImageIcon leftButtonIcon = createImageIcon("images/right.gif");
    ImageIcon middleButtonIcon = createImageIcon("images/middle.gif");
    ImageIcon rightButtonIcon = createImageIcon("images/left.gif");
    b1 = new JButton("Disable middle button", leftButtonIcon);
    b1.setVerticalTextPosition(AbstractButton.CENTER);
    b1.setHorizontalTextPosition(AbstractButton.LEADING); //aka LEFT, for left-to-right locales
    b1.setMnemonic(KeyEvent.VK_D);
    b1.setActionCommand("disable");
    b2 = new JButton("Middle button", middleButtonIcon);
    b2.setVerticalTextPosition(AbstractButton.BOTTOM);
    b2.setHorizontalTextPosition(AbstractButton.CENTER);
    b2.setMnemonic(KeyEvent.VK_M);
    b3 = new JButton("Enable middle button", rightButtonIcon);
    //Use the default text position of CENTER, TRAILING (RIGHT).
    b3.setMnemonic(KeyEvent.VK_E);
    b3.setActionCommand("enable");
    b3.setEnabled(false);
    //Listen for actions on buttons 1 and 3.
    b1.addActionListener(this);
    b3.addActionListener(this);
    b1.setToolTipText("Click this button to disable "
                      + "the middle button.");
    b2.setToolTipText("This middle button does nothing "
                      + "when you click it.");
    b3.setToolTipText("Click this button to enable the "
                      + "middle button.");
    ...
}
public void actionPerformed(ActionEvent e) {
    if ("disable".equals(e.getActionCommand())) {
        b2.setEnabled(false);
        b1.setEnabled(false);
        b3.setEnabled(true);
    } else {
        b2.setEnabled(true);
        b1.setEnabled(true);
        b3.setEnabled(false);
    }
} 
protected static ImageIcon createImageIcon(String path) {
    java.net.URL imgURL = ButtonDemo.class.getResource(path);
    *...//error handling omitted for clarity...*
    return new ImageIcon(imgURL);
}