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Posts Tagged ‘location-api’

JavaME JSR-179 Example Code : Detect Location via TinyGeocoder

February 22nd, 2009 4 Comments   Posted in J2ME / JavaME, Location API, Open Source, Smartphone, Tips, Tricks, Guide

I've completed the JSR-179 Location API code for reverse geocoding in JavaME. This code essentially is an expansion of the previous JSR-179 example that i've posted in the blog before, plus the Reverse-Geocoding feature, thanks to TinyGeocoder service.

J2ME GPS Reverse Geocoding mypapit

What this sample MIDlet does?
It obtain coordinates via the mobile phone JSR-179 Location API and subsequently display the name of the location using TinyGeocoder reverse geocoding service.

PLAIN TEXT
JAVA:
  1. import javax.microedition.midlet.*;
  2. import javax.microedition.lcdui.*;
  3. import javax.microedition.location.*;
  4. import javax.microedition.io.*;
  5. import javax.microedition.location.*;
  6. import java.io.*;
  7.  
  8. public class Geocoder extends MIDlet implements CommandListener
  9. {
  10.     public Display display;
  11.     public Form form;
  12.     private Command cmdExit,cmdOK;
  13.     public StringItem si, sili;
  14.  
  15.     public Geocoder()
  16.     {
  17.  
  18.         display =Display.getDisplay(this);
  19.         form = new Form("Location Api test");
  20.         cmdExit = new Command("Exit",Command.EXIT,5);
  21.         cmdOK = new Command("OK",Command.OK,1);
  22.         si = new StringItem("Coordinates", "Press OK");
  23.         sili = new StringItem("Location", "");
  24.         form.append(si);
  25.         form.append(sili);
  26.         form.addCommand(cmdOK);
  27.         form.addCommand(cmdExit);
  28.         form.setCommandListener(this);
  29.     }
  30.  
  31.     public void startApp()
  32.     {
  33.         display.setCurrent(form);
  34.     }
  35.  
  36.  
  37.     public void pauseApp()
  38.     {}
  39.  
  40.     public void destroyApp(boolean flag) {
  41.         notifyDestroyed();
  42.     }
  43.  
  44.     public void commandAction(Command c, Displayable d)
  45.     {
  46.         if (c == cmdOK){
  47.             Retriever ret = new Retriever(this);
  48.             ret.start();
  49.  
  50.         } else if (c == cmdExit) {
  51.             destroyApp(false);
  52.         }
  53.     }
  54.  
  55.     public void displayString(String string)
  56.     {
  57.         si.setText(string);
  58.     }
  59.  
  60.     public void showAlert(String message) {
  61.         Alert alert = new Alert("Alert",message,null,AlertType.WARNING);
  62.         display.setCurrent(alert,form);
  63.     }
  64.  
  65.  
  66.  
  67.  
  68. }
  69.  
  70. class Retriever extends Thread {
  71.  
  72.     private Geocoder midlet;
  73.     Form formRunning;
  74.     Gauge gauge;
  75.  
  76.  
  77.  
  78.     public Retriever(Geocoder midlet)
  79.         {
  80.             /**
  81.               * Constructor
  82.               *
  83.               * EFFECTS: Initialise the server and store midlet information
  84.               *
  85.               * @param midlet The main application midlet
  86.               * @param server Forecast Server URL
  87.               *
  88.               */
  89.             this.midlet = midlet;
  90.             formRunning = new Form("Retrieving Info");
  91.             formRunning.append(new Gauge("Processing",false,Gauge.INDEFINITE,Gauge.CONTINUOUS_RUNNING));
  92.             midlet.display.setCurrent(formRunning);
  93.  
  94.     }
  95.  
  96.     public void run()
  97.         {
  98.             /**
  99.             * Entry point of the thread
  100.             *
  101.             * EFFECTS: call to connect() method
  102.             */
  103.             try {
  104.                             checkLocation();
  105.                         } catch (Exception ex)
  106.                         {
  107.                             ex.printStackTrace();
  108.                             midlet.displayString(ex.toString());
  109.             } finally {
  110.  
  111.             }
  112.  
  113.  
  114.         }
  115.  
  116.     public void checkLocation() throws Exception
  117.     {
  118.         String string;
  119.         Location l;
  120.         LocationProvider lp;
  121.         Coordinates c;
  122.         // Set criteria for selecting a location provider:
  123.         // accurate to 500 meters horizontally
  124.         Criteria cr= new Criteria();
  125.         cr.setHorizontalAccuracy(5000);
  126.         cr.setVerticalAccuracy(5000);
  127.  
  128.         // Get an instance of the provider
  129.         lp= LocationProvider.getInstance(cr);
  130.  
  131.         // Request the location, setting a one-minute timeout
  132.         l = lp.getLocation(120);
  133.         c = l.getQualifiedCoordinates();
  134.  
  135.         if(c != null ) {
  136.           // Use coordinate information
  137.           double lat = c.getLatitude();
  138.           double lon = c.getLongitude();
  139.           string = "\nLatitude : " + lat + "\nLongitude : " + lon;
  140.           new GetData(midlet,lat,lon).start();
  141.  
  142.         } else {
  143.             string ="Location API failed";
  144.         }
  145.  
  146.         formRunning.append("Obtained coordinates...");
  147.         midlet.displayString(string);
  148.     }
  149. }
  150.  
  151. class GetData implements Runnable,CommandListener {
  152.  
  153. Geocoder midlet;
  154. double lat, lon;
  155.  
  156. public GetData (Geocoder midlet, double lat, double lon) {
  157.  
  158.     this.lat = lat;
  159.     this.lon = lon;
  160.     this.midlet = midlet;
  161.  
  162.  
  163. }
  164.  
  165. public void commandAction (Command cmd,Displayable disp)
  166. {
  167.  
  168. }
  169.  
  170. public void start() {
  171.        Thread t = new Thread(this);
  172.        t.start();
  173. }
  174.  
  175.  
  176. public void run() {
  177.     HttpConnection conn=null;
  178.     InputStream is=null;
  179.     String sb;
  180.  
  181.     try {
  182.             String sUrl = "http://tinygeocoder.com/create-api.php?g="+""+lat+","+""+lon;
  183.             conn = (HttpConnection) Connector.open(sUrl,Connector.READ);
  184.             if (conn.getResponseCode() == HttpConnection.HTTP_OK) {
  185.                     is = conn.openInputStream();
  186.                     byte buf[] = new byte[128];
  187.                     int total =0;
  188.                     while (total <128) {
  189.                         int count = is.read(buf,total,128-total);
  190.                         if (count<0) {
  191.                             break;
  192.                         }
  193.                         total += count;
  194.                     }
  195.  
  196.                     sb = new String(buf,0,total);
  197.  
  198.                     if (sb.length() <10) {
  199.                             midlet.showAlert("Connection error, please try again");
  200.                             is.close();
  201.                             conn.close();
  202.  
  203.                             return;
  204.                     }
  205.  
  206.                       midlet.sili.setText(sb);
  207.                     //midlet.form.append(sb);
  208.                     //vectorized();
  209.                     //midlet.saveCurrency(false,midlet.vector);
  210.                     //midlet.display.setCurrent(midlet.form);
  211.             } else if (conn.getResponseCode() == HttpConnection.HTTP_NOT_FOUND) {
  212.                     midlet.showAlert("URL not found");
  213.  
  214.             } else {
  215.                 midlet.showAlert("Server busy or unavailable. Please try again later");
  216.             }
  217.  
  218.     } catch (SecurityException sex) {
  219.         midlet.showAlert("Connection failed. You need to authorize this application to access network");
  220.     } catch (IOException ioex) {
  221.             midlet.showAlert("Connection failed. Please try again later.");
  222.     } catch (Exception e){
  223.         midlet.showAlert(e.toString());
  224.         e.printStackTrace();
  225.         //midlet.display.setCurrent(midlet.form);
  226.     } finally {
  227.         try {
  228.             if (is != null) {
  229.                 is.close();
  230.             }
  231.  
  232.             if (conn != null) {
  233.                 conn.close();
  234.             }
  235.         } catch (IOException ioexception) {}
  236.             is =null;
  237.             conn =null;
  238.             midlet.display.setCurrent(midlet.form);
  239.  
  240.  
  241.     }
  242. }
  243.  
  244.  
  245. public String URLEncode(String s)
  246. {
  247.         if (s!=null) {
  248.             StringBuffer tmp = new StringBuffer();
  249.             int i=0;
  250.             try {
  251.                 while (true) {
  252.                     int b = (int)s.charAt(i++);
  253.                     if ((b>=0x30 && b<=0x39) || (b>=0x41 && b<=0x5A) || (b>=0x61 && b<=0x7A)) {
  254.                         tmp.append((char)b);
  255.                     }
  256.                     else {
  257.                         tmp.append("%");
  258.                         if (b <= 0xf) tmp.append("0");
  259.                         tmp.append(Integer.toHexString(b));
  260.                     }
  261.                 }
  262.             }
  263.             catch (Exception e) {}
  264.             return tmp.toString();
  265.         }
  266.         return null;
  267. }
  268. }

The code requires mobile device which implements JSR-179 Location API and has been tested on Nokia E71 and 6210 Navigator.


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TinyGeo-coder : A cool free geocoding/reverse geocoding service

February 9th, 2009 4 Comments   Posted in Web Service

I was searching for a free and easy to use geocoding web service over the internet for my experiment involving Location Based Service (LBS). Then suddenly i came accross tinygeocoder, a web service which really suits my need.

tinygeocoder services that caught my eye :

  • geocoding - you can feed it with name of place like "San Francisco, CA" and it will return result in latitude and longitude pair "(37.775196,-122.419204)"
  • reverse geocoding - feed it with a coordinate, and the service will return you the name of the corresponding place.

Personally I like the "reverse geocoding" functionality more as it would be handy for my LBS project. Keep an eye for this blog as I'll be posting JavaME JSR-179 (Location API) codes which utilizes tinygeocoder services.

p/s: If you find tinygeoder helpful, consider making donations to them.


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I bought a new phone – Nokia E71

December 26th, 2008 4 Comments   Posted in J2ME / JavaME, Java, Nokia, Smartphone, Symbian

I know I've been slacking lately on my post.. but hey, I got myself a new phone - The Nokia E71!

Phones model and features are getting diverse now and I've noticed that its getting harder and harder to choose a phone that really suits my needs. For example, one feature found on Phone A isnt necessarily can be found on Phone B.

So it took me a while to replace my good old 6630 that has been stolen few months before. But hey, I'm back on my feet now.

Nokia E71 papit

Among the key feature that attract me to buy this phone are :

  • Location API support (JSR-179) with built in GPS receiver
  • QWERTY keyboard
  • Ease of handling, my hands a bit slippy on its sister's phone E66
  • Battery last longer
  • Hot swappable micro-sd card
  • More than adequate internal memory

    • \

  • Supports WiFi

The only drawback that I could think of this phone is its camera that is not as good as the N95,N96 series phone. But I can still live with that since I rarely use the camera anyway.

Other additional feature
The phone comes with Advance Call Manager and Multi Scanner free of charge, making it easier to filter out unwanted call and to manage phone blacklist.

Multi Scanner allows you to take a photo of name card and automatically store important information (Name, Phone Number, Address, Company's Name, Fax Number) right into the phone.

I hope I can be more productive at updating this blog and producing new mobile applications with this phone.


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