Unique device id

Is there any unique id on Android Mobile?? If it is then how many digit it has? How can I access that through my program??

Thanks D开发者_如何学Goeepak

There are several problems that occur when using IMEI, IMSI... that are described here:

http://android-developers.blogspot.pt/2011/03/identifying-app-installations.html

The recommended approach is to use:

http://developer.android.com/reference/android/provider/Settings.Secure.html#ANDROID_ID

String unique_id = android.provider.Settings.Secure.getString(getContentResolver(), android.provider.Settings.Secure.ANDROID_ID);

check IMEI.

http://www.anddev.org/tinytut_-_getting_the_imsi_-_imei_sim-device_unique_ids-t446.html

For detailed instructions on how to get a Unique Identifier for each Android device your application is installed from, see this official Android Developers Blog posting:

http://android-developers.blogspot.com/2011/03/identifying-app-installations.html

It seems the best way is for you to generate one your self upon installation and subsequently read it when the application is re-launched.

I personally find this acceptable but not ideal. No one identifier provided by Android works in all instances as most are dependent on the phone's radio states (wifi on/off, cellular on/off, bluetooth on/off). The others like Settings.Secure.ANDROID_ID must be implemented by the manufacturer and are not guaranteed to be unique.

The following is an example of writing data to an INSTALLATION file that would be stored along with any other data the application saves locally.

public class Installation {
    private static String sID = null;
    private static final String INSTALLATION = "INSTALLATION";

    public synchronized static String id(Context context) {
        if (sID == null) {  
            File installation = new File(context.getFilesDir(), INSTALLATION);
            try {
                if (!installation.exists())
                    writeInstallationFile(installation);
                sID = readInstallationFile(installation);
            } catch (Exception e) {
                throw new RuntimeException(e);
            }
        }
        return sID;
    }

    private static String readInstallationFile(File installation) throws IOException {
        RandomAccessFile f = new RandomAccessFile(installation, "r");
        byte[] bytes = new byte[(int) f.length()];
        f.readFully(bytes);
        f.close();
        return new String(bytes);
    }

    private static void writeInstallationFile(File installation) throws IOException {
        FileOutputStream out = new FileOutputStream(installation);
        String id = UUID.randomUUID().toString();
        out.write(id.getBytes());
        out.close();
    }
}