compass.java

这是一个手机上的J2ME程序

// J2ME Compass 4.0
// Copyright (C) 2007 Dana Peters
// http://www.qcontinuum.org/compass

// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// the License, or (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

// Floating point calculations performed using:
// henson.midp.Float (C) by Nikolay Klimchuk
// http://henson.newmail.ru

// Global airport database provided by:
// http://www.partow.net/miscellaneous/airportdatabase/
// GlobalAirportDatabase.txt converted to GlobalAirportDatabase.dat
// using script AirportsTxtToDat.vbs

package org.qcontinuum.compass;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.util.*;
import org.qcontinuum.astro.*;
import henson.midp.Float;

public class Compass extends MIDlet {

    final static private int REFRESHMILLIS = 10 * 60 * 1000;

    private static Compass sCompass;
    private static Display sDisplay;
    private static CompassCanvas sCompassCanvas;
    private static Preferences sPreferences;
    private static Timer sTimer;
    private static Date sDate;
    private static boolean sRefresh;

    public Compass() {
        sCompass = this;
    }

    public void startApp() {
        sDisplay = Display.getDisplay(this);
        sPreferences = new Preferences();
        sCompassCanvas = new CompassCanvas();
        sDate = new Date(System.currentTimeMillis());
        sTimer = new Timer();
        sTimer.schedule(new RefreshTimerTask(), REFRESHMILLIS, REFRESHMILLIS);
        display(sCompassCanvas);
    }
    
    public void pauseApp() {
    }

    public void destroyApp(boolean unconditional) {
    }

    public static void exit() {
        sTimer.cancel();
        sCompass.destroyApp(true);
        sCompass.notifyDestroyed();
        sCompass = null;
    }

    public static void setRefresh(boolean refresh) {
        sRefresh = refresh;
    }
    
    public static boolean getRefresh() {
        return sRefresh;
    }
    
    public static Date getDate() {
        return sDate;
    }

    public static void setDate(Date newDate) {
        sDate = newDate;
        sRefresh = true;
    }

    public class RefreshTimerTask extends TimerTask {
        public void run() {
            if (updateDate()) {
                if (sCompassCanvas.isShown())
                    sCompassCanvas.repaint();
            }
        }
    }

    public static boolean updateDate() {
        long currentTimeMillis = System.currentTimeMillis();
        if (Math.abs(currentTimeMillis - sDate.getTime()) < REFRESHMILLIS + 5000) {
            setDate(new Date(System.currentTimeMillis()));
            return true;
        }
        return false;
    }
    
    public static void display(Displayable displayable) {
        sDisplay.setCurrent(displayable);
    }

    public static void display() {
        display(sCompassCanvas);
    }

    public static void display(Alert alert, Displayable displayable) {
            sDisplay.setCurrent(alert, displayable);
    }

    public static void display(Alert alert) {
        display(alert, sCompassCanvas);
    }

    public static void display(Exception e, Displayable displayable) {
        Alert alert = new Alert("Error",
                "Exception: " + e.getClass().getName() + " " + e.getMessage(), null, AlertType.ERROR);
        alert.setTimeout(Alert.FOREVER);
        sDisplay.setCurrent(alert, displayable);
    }

    public static void display(Exception e) {
        display(e, sCompassCanvas);
    }

    public static void display(String text, int seconds, Displayable displayable) {
        Alert alert = new Alert("Compass");
        alert.setTimeout(seconds == 0 ? Alert.FOREVER : seconds * 1000);
        alert.setType(AlertType.INFO);
        alert.setString(text);
        display(alert, displayable);
    }

    public static void display(String text, int seconds) {
        display(text, seconds, sCompassCanvas);
    }

    public static void display(String text, Displayable displayable) {
        display(text, 0, displayable);
    }
    
    public static void display(String text) {
        display(text, 0, sCompassCanvas);
    }
    
    public static Display getDisplay() {
        return sDisplay;
    }
    
    public static Preferences getPreferences() {
        return sPreferences;
    }

    public static String getFloat(Float f, int decimals) {
        StringBuffer sb = new StringBuffer();
        sb.append(Float.Int(f).toLong());
        sb.append('.');
        int i;
        Float n = Float.abs(f);
        for (i = 0; i < decimals; i++) {
            n = Float.Frac(n).Mul(10);
            sb.append(Float.Int(n).toLong());
        }
        return sb.toString();
    }

    public static String getTime(UtcDate utcDate) {
        StringBuffer sb = new StringBuffer();
        if (utcDate == null)
            sb.append("none");
        else
            if (sPreferences.Hour24)
                sb.append(utcDate.get24HourTimeString());
            else
                sb.append(utcDate.get12HourTimeString());
        return sb.toString();
    }
}