DeviceUuidFactory.java

/**
 * 
 */
package coolbuy360.logic;

/**
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 */
import java.io.UnsupportedEncodingException;
import java.util.UUID;

import android.content.Context;
import android.content.SharedPreferences;
import android.provider.Settings.Secure;
import android.telephony.TelephonyManager;
public class DeviceUuidFactory { 
    protected static final String PREFS_FILE = "device_id"; 
    protected static final String PREFS_DEVICE_ID = "device_id"; 
    protected static UUID uuid; 
 
    public DeviceUuidFactory(Context context) 
    { 
        if( uuid ==null ) 
        { 
            synchronized (DeviceUuidFactory.class) 
            { 
                if( uuid == null) 
                { 
                    final SharedPreferences prefs = context.getSharedPreferences( PREFS_FILE, 0); 
                    final String id = prefs.getString(PREFS_DEVICE_ID, null ); 
                    if (id != null) 
                    { 
                        // Use the ids previously computed and stored in the prefs file 
                        uuid = UUID.fromString(id); 
                    } 
                    else 
                    { 
                        final String androidId = Secure.getString(context.getContentResolver(), Secure.ANDROID_ID); 
                        // Use the Android ID unless it's broken, in which case fallback on deviceId, 
                        // unless it's not available, then fallback on a random number which we store 
                        // to a prefs file 
                        try 
                        { 
                            if (androidId!=null && !"9774d56d682e549c".equals(androidId)) 
                            { 
                                uuid = UUID.nameUUIDFromBytes(androidId.getBytes("utf8")); 
                            } 
                            else 
                            { 
                                final String deviceId = ((TelephonyManager) context.getSystemService( Context.TELEPHONY_SERVICE )).getDeviceId(); 
                                if(deviceId==null || deviceId.equals("000000000000000"))
                                {
                                	uuid = UUID.randomUUID(); 
                                }else {
                                	uuid = UUID.nameUUIDFromBytes(deviceId.getBytes("utf8"));
								}
                            } 
                        } 
                        catch (UnsupportedEncodingException e) 
                        { 
                            throw new RuntimeException(e); 
                        } 
                        // Write the value out to the prefs file 
                        prefs.edit().putString(PREFS_DEVICE_ID, uuid.toString() ).commit(); 
                    } 
                } 
            } 
        } 
    } 
 
    /**
     * Returns a unique UUID for the current android device.  As with all UUIDs, this unique ID is "very highly likely"
     * to be unique across all Android devices.  Much more so than ANDROID_ID is.
     *
     * The UUID is generated by using ANDROID_ID as the base key if appropriate, falling back on
     * TelephonyManager.getDeviceID() if ANDROID_ID is known to be incorrect, and finally falling back
     * on a random UUID that's persisted to SharedPreferences if getDeviceID() does not return a
     * usable value.
     *
     * In some rare circumstances, this ID may change.  In particular, if the device is factory reset a new device ID
     * may be generated.  In addition, if a user upgrades their phone from certain buggy implementations of Android 2.2
     * to a newer, non-buggy version of Android, the device ID may change.  Or, if a user uninstalls your app on
     * a device that has neither a proper Android ID nor a Device ID, this ID may change on reinstallation.
     *
     * Note that if the code falls back on using TelephonyManager.getDeviceId(), the resulting ID will NOT
     * change after a factory reset.  Something to be aware of.
     *
     * Works around a bug in Android 2.2 for many devices when using ANDROID_ID directly.
     *
     * @see http://code.google.com/p/android/issues/detail?id=10603
     *
     * @return a UUID that may be used to uniquely identify your device for most purposes.
     */ 
    public UUID getDeviceUuid() 
    { 
        return uuid; 
    } 
}