*--------------------------------------------------
* AnimatedTimer - Main midlet.
* Shows canvas with an animated timer. Includes
* configuration options to start/stop the timer
* and to adjust the sleep interval of the thread
*
* Example from the book: Core J2ME Technology
* Copyright John W. MUChow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
import java.util.Stack;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.Gauge;
import javax.microedition.lcdui.Graphics;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.List;
import javax.microedition.midlet.MIDlet;
public class AnimatedTimer extends MIDlet {
PRivate Display display; // The display
protected TimerCanvas cvTimer; // Canvas to display timer
protected OptionsList lsOptions; // List to change timer options
protected SleepForm fmSleep; // Form with gauge to set timer sleep
protected DisplayManager displayMgr; // Class to help manage screens
public AnimatedTimer() {
display = Display.getDisplay(this);
cvTimer = new TimerCanvas(this);
lsOptions = new OptionsList("Timer options", List.IMPLICIT, this);
fmSleep = new SleepForm("Adjust sleep", this);
// Create a display manager object
displayMgr = new DisplayManager(display, cvTimer);
}
protected void startApp() {
// Start with the canvas
display.setCurrent(cvTimer);
}
protected void pauseApp() {
}
protected void destroyApp(boolean unconditional) {
}
public void exitMIDlet() {
destroyApp(true);
notifyDestroyed();
}
}
/*--------------------------------------------------
* Use a stack to push and pop displayable objects
*
* public void pushDisplayable(Displayable)
* public void popDisplayable()
* public void home()
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
class DisplayManager extends Stack {
private Display display; // Reference to Display object
private Displayable mainDisplayable; // Main displayable for MIDlet
private Alert alStackError; // Alert for error conditions
/*--------------------------------------------------
* Display manager constructor
*-------------------------------------------------*/
public DisplayManager(Display display, Displayable mainDisplayable) {
// Only one display object per midlet, this is it
this.display = display;
this.mainDisplayable = mainDisplayable;
// Create an alert displayed when an error occurs
alStackError = new Alert("Displayable Stack Error");
alStackError.setTimeout(Alert.FOREVER); // Modal
}
/*--------------------------------------------------
* Push the current displayable onto stack and set
* the passed in displayable as active
*-------------------------------------------------*/
public void pushDisplayable(Displayable newDisplayable) {
push(display.getCurrent());
display.setCurrent(newDisplayable);
}
/*--------------------------------------------------
* Return to the main displayable object of MIDlet
*-------------------------------------------------*/
public void home() {
while (elementCount > 1)
pop();
display.setCurrent(mainDisplayable);
}
/*--------------------------------------------------
* Pop displayable from stack and set as active
*-------------------------------------------------*/
public void popDisplayable() {
// If the stack is not empty, pop next displayable
if (empty() == false)
display.setCurrent((Displayable) pop());
else
// On error show an alert
// Once acknowledged, set 'mainDisplayable' as active
display.setCurrent(alStackError, mainDisplayable);
}
}
/*--------------------------------------------------
* Class TimerCanvas
*
* Animate a sequence of images to simulate
* a moving timer
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
class TimerCanvas extends Canvas implements Runnable, CommandListener {
private AnimatedTimer midlet; // Main midlet
private Command cmExit; // Exit midlet
private Command cmOptions; // Display options list
private Image im = null; // Sequence of images
private int imageCount = 4; // Four images in the sequence
private int imageWidth; // Width of one image in the sequence
private int imageHeight; // Height of one image in the sequence
private int imageIndex; // Current image in the sequence
private int translate_x; // Translated x and y
private int translate_y;
private int viewport_x; // Location of the viewport
private int viewport_y;
private boolean active = false; // Timer active?
private boolean requestedToStop = false; // Did user request to stop timer
private int sleepTime = 400; // Current sleep time (milliseconds)
public TimerCanvas(AnimatedTimer midlet) {
// Call canvas constructor
super();
// Save reference to MIDlet so we can
// access the display manager class
this.midlet = midlet;
// Create commands & listen for events
cmExit = new Command("Exit", Command.EXIT, 1);
cmOptions = new Command("Config", Command.SCREEN, 2);
addCommand(cmExit);
addCommand(cmOptions);
setCommandListener(this);
}
/*--------------------------------------------------
* application manager is about to display canvas
*-------------------------------------------------*/
protected void showNotify() {
if (im == null) {
try {
// Read the png from a file and get width and
// height of one image in the sequence
im = Image.createImage("/timer.png");
imageHeight = im.getHeight();
imageWidth = im.getWidth() / imageCount;
// Get the coordinates for x/y of viewport
// Viewport is centered on the display
viewport_x = (getWidth() / 2) - (imageWidth / 2);
viewport_y = (getHeight() / 2) - (imageHeight / 2);
// Set first translated coordinate to match viewport
translate_x = viewport_x;
translate_y = viewport_y;
} catch (Exception e) {
System.err.println("Unable to read png file.");
}
// Begin with the first image in the sequence
imageIndex = 0;
}
// If the user has not requested to stop the timer...
if (!requestedToStop)
active = true;
new Thread(this).start();
}
/*--------------------------------------------------
* Application manager is no longer displaying canvas
*-------------------------------------------------*/
protected void hideNotify() {
active = false;
}
/*--------------------------------------------------
* Draw next timer in sequence
*-------------------------------------------------*/
protected void paint(Graphics g) {
if (im != null) {
// Due to a bug in MIDP 1.0.3 we need to
// force a clear of the display
g.setColor(255, 255, 255); // White pen
g.fillRect(0, 0, getWidth(), getHeight());
g.setColor(0, 0, 0); // Black pen
// Viewport at center of display
g.setClip(viewport_x, viewport_y, imageWidth, imageHeight);
// Draw image at translated coordinates
g.drawImage(im, translate_x, translate_y, Graphics.TOP
Graphics.LEFT);
}
}
/*--------------------------------------------------
* Loop forever, translating image coordinates
*-------------------------------------------------*/
public void run() {
try {
while (active) {
Thread.sleep(sleepTime);
repaint();
// Reached the last image in sequence
if (imageIndex == imageCount - 1) {
// Reset translated coordinates
translate_x = viewport_x;
translate_y = viewport_y;
} else {
// Translate coordinate system to the left
translate_x -= imageWidth;
}
// Which image in the sequence is next
imageIndex = (imageIndex + 1) % imageCount;
}
} catch (InterruptedException e) {
}
}
/*--------------------------------------------------
* Called from the "Config" options menu
*-------------------------------------------------*/
public void startTimer() {
requestedToStop = false;
active = true;
repaint();
}
/*--------------------------------------------------
* Called from the "Config" options menu
*-------------------------------------------------*/
public void stopTimer() {
requestedToStop = true;
active = false;
repaint();
}
/*--------------------------------------------------
* Called from form/gauge to adjust sleep
*-------------------------------------------------*/
public void setSleep(int sleepTime) {
this.sleepTime = sleepTime;
}
/*--------------------------------------------------
* Called from form/gauge to adjust sleep
*-------------------------------------------------*/
public int getSleep() {
return sleepTime;
}
/*--------------------------------------------------
* Command event handling
*-------------------------------------------------*/
public void commandAction(Command c, Displayable s) {
if (c == cmOptions) {
// Push current displayable and show the options list
midlet.displayMgr.pushDisplayable(midlet.lsOptions);
} else if (c == cmExit) {
midlet.exitMIDlet();
}
}
}
/*--------------------------------------------------
* Class SleepForm
*
* Form with gauge to adjust sleep interval of timer
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
class SleepForm extends Form implements CommandListener {
private AnimatedTimer midlet; // Main midlet
private Command cmBack, // Back to options list
cmHome, // Go to main displayable (canvas)
cmSave; // Save new sleep time
private Gauge gaSleep; // Gauge to adjust sleep
public SleepForm(String title, AnimatedTimer midlet) {
// Call the form constructor
super(title);
// Save reference to MIDlet so we can
// access the display manager class
this.midlet = midlet;
// Commands
cmSave = new Command("Save", Command.SCREEN, 1);
cmBack = new Command("Back", Command.BACK, 2);
cmHome = new Command("Home", Command.SCREEN, 2);
// Gauge to adjust the length of timer sleep
gaSleep = new Gauge("Timer Sleep", true, 100, 1000);
// Set to current sleep. Gauge holds values 0 to 100,
// divide the current sleep (milliseconds) by 10
gaSleep.setValue(midlet.cvTimer.getSleep() / 10);
// Add to form and listen for events
append(gaSleep);
addCommand(cmSave);
addCommand(cmBack);
addCommand(cmHome);
setCommandListener(this);
}
/*--------------------------------------------------
* Command event handling
*-------------------------------------------------*/
public void commandAction(Command c, Displayable s) {
if (c == cmSave) {
// Gauge returns a value between 0 and 100
// We want milliseconds, so multiply by 10
midlet.cvTimer.setSleep(gaSleep.getValue() * 10);
// Return to main midlet
midlet.displayMgr.home();
} else if (c == cmBack) {
// Pop the last displayable off the stack
midlet.displayMgr.popDisplayable();
} else if (c == cmHome) {
// Return to main midlet
midlet.displayMgr.home();
}
}
}
/*--------------------------------------------------
* Class OptionsList
*
* List to provide options for configuring of timer
*
* Example from the book: Core J2ME Technology
* Copyright John W. Muchow http://www.CoreJ2ME.com
* You may use/modify for any non-commercial purpose
*-------------------------------------------------*/
class OptionsList extends List implements CommandListener {
private AnimatedTimer midlet; // Main midlet
private Command cmBack;
public OptionsList(String title, int listType, AnimatedTimer midlet) {
// Call list constructor
super(title, listType);
// Save reference to MIDlet so we can
// access the display manager class
this.midlet = midlet;
// Create the list entries
append("Sleep interval", null);
append("Start", null);
append("Stop", null);
// Create command and listen for events
cmBack = new Command("Back", Command.BACK, 1);
addCommand(cmBack);
setCommandListener(this);
}
/*--------------------------------------------------
* Command event handling
*-------------------------------------------------*/
public void commandAction(Command c, Displayable s) {
// Event generated by the implicit list
if (c == List.SELECT_COMMAND) {
switch (getSelectedIndex()) {
case 0:
// Push current displayable and show the form
// to adjust the timer sleep
midlet.displayMgr.pushDisplayable(midlet.fmSleep);
break;
case 1:
// Start timer and return to previous displayable
midlet.cvTimer.startTimer();
midlet.displayMgr.popDisplayable();
break;
case 2:
// Stop timer and return to previous displayable
midlet.cvTimer.stopTimer();
midlet.displayMgr.popDisplayable();
break;
}
} else if (c == cmBack) {
// Return to previous displayable
midlet.displayMgr.popDisplayable();
}
}
}
（出处：http://www.knowsky.com）
