clock.java

用编写的一个时钟程序

//Listing 6-6 -- Clock.java
import java.applet.*;
import java.awt.*;
public class Clock extends Applet implements Runnable {
    private Thread th_thread;	// Thread for the runnable interface
    private Image im_images[];   // Image array for animation
    private int i_currImage;  // Current Image to display
    private int i_imageWidth  = 0;  //Width of Image
    private int i_imageHeight = 0;  // Height of Image
// Boolean set to true when all the images have loaded
    private boolean  b_allLoaded = false;	// Boolean for all loaded
    private final int i_numImages = 12;  // Number of Images
    public void init() {
        resize(320, 240);
        //Run thread, which calls the run method
        th_thread = new Thread(this);
        th_thread.start();
    }
    public void run() {    // Called for Thread support.
        i_currImage   = 0;
        String imageName;
    // Array to store images
        im_images   = new Image[i_numImages];
        Graphics g = getGraphics();
        showStatus("Loading images...");
        for (int i = 1; i <= i_numImages; i++) {
            String picNum = Integer.toString(i);
            if (picNum.length() < 2) {
                picNum = "0" + picNum;
            }
            imageName = "CLOCK" + picNum + ".gif";  // Image file
            im_images[i-1] = getImage(
                    getDocumentBase(), imageName);
            // Get width and height of one image. Assume
            // all images are same width and height
            if (i_imageWidth == 0) {
                try    {
                    while ((i_imageWidth =
                          im_images[i-1].getWidth(null)) < 0)
                        Thread.sleep(1);
                    while ((i_imageHeight =
                         im_images[i-1].getHeight(null)) < 0)
                        Thread.sleep(1);
                }
                catch (InterruptedException e) { }
            }
            // Force image to fully load
            g.drawImage(im_images[i-1], -1000, -1000, this);
        }
        // Wait until images are fully loaded
        while (!b_allLoaded) {
            try { Thread.sleep(10); }
            catch (InterruptedException e) { }
        }
        showStatus("Done loading images.");
        while (true) {
            try { // Draw next image in animation
                displayImage(g);
                i_currImage++;
                if (i_currImage == i_numImages)
                    i_currImage = 0;
                Thread.sleep(500);
            }
            catch (InterruptedException e) {stop();}
        }
    }
    private void displayImage(Graphics g) {
        if (!b_allLoaded)
            return;
        g.drawImage(im_images[i_currImage], 
               (getSize().width - i_imageWidth)   / 2,
               (getSize().height - i_imageHeight) / 2, null);
    }
    public void paint(Graphics g) {
        if (b_allLoaded) {
            Rectangle r = g.getClipBounds();
            g.clearRect(r.x, r.y, r.width, r.height);
            displayImage(g);
        }
    }
    public boolean imageUpdate(Image img, int flags,
                              int x, int y, int w, int h) {
        // Nothing to do if images are all loaded
        if (b_allLoaded)
            return false;
        // Want all bits to be available before painting
        if ((flags & ALLBITS) == 0)
            return true;
        // All bits are available, so increment loaded count
        // of fully loaded images, starting animation if all
        // images are loaded
        if (++i_currImage == i_numImages) {
            i_currImage = 0;
            b_allLoaded = true;
        }                
        return false;
    }
    public void stop() {
        if (th_thread != null) {
            th_thread.stop();
            th_thread = null;
        }
    }
}