Connecting with GCM, and getting Registration ID.

CloudProcessor.java

/**
 * 
 * @author Rachit Mishra
 * @licence The MIT License (MIT) Copyright (c) <2013> <Rachit Mishra> 
 *
 */

import android.app.IntentService;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.NotificationCompat;

import com.google.android.gms.gcm.GoogleCloudMessaging;

public class CloudProcessor extends IntentService {

	public CloudProcessor() {
		super("CloudProcessor");
	}

	public static final int NOTIFICATION_ID = 1;
	private NotificationManager mNotificationManager;
	private GoogleCloudMessaging gcm;

	@Override
	protected void onHandleIntent(Intent intent) {
		Bundle extras = intent.getExtras();
		gcm = GoogleCloudMessaging.getInstance(this);
		String messageType = gcm.getMessageType(intent);

		if (!extras.isEmpty()) {
			if (GoogleCloudMessaging.MESSAGE_TYPE_SEND_ERROR
					.equals(messageType)) {
				sendNotification("Send error: " + extras.toString());
			} else if (GoogleCloudMessaging.MESSAGE_TYPE_DELETED
					.equals(messageType)) {
				sendNotification("Deleted messages on server: "
						+ extras.toString());
			} else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE
					.equals(messageType)) {
				sendNotification("Deleted messages on server: "
						+ extras.toString());
			}
		}

		CloudReceiver.completeWakefulIntent(intent);

	}

	private void sendNotification(String msg) {
		mNotificationManager = (NotificationManager) this
				.getSystemService(Context.NOTIFICATION_SERVICE);

		PendingIntent contentIntent = PendingIntent.getActivity(this, 0,
				new Intent(this, Home.class), 0);

		NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(
				this).setSmallIcon(R.drawable.ic_launcher)
				.setContentTitle("GCM Notification")
				.setStyle(new NotificationCompat.BigTextStyle().bigText(msg))
				.setContentText(msg);

		mBuilder.setContentIntent(contentIntent);
		mNotificationManager.notify(NOTIFICATION_ID, mBuilder.build());
	}
}

CloudReceiver.java

import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.support.v4.content.WakefulBroadcastReceiver;

public class CloudReceiver extends WakefulBroadcastReceiver {
	public CloudReceiver() {
	}

	@Override
	public void onReceive(Context context, Intent intent) {
		ComponentName component = new ComponentName(context.getPackageName(),
				CloudProcessor.class.getName());
		startWakefulService(context, (intent.setComponent(component)));
		setResultCode(Activity.RESULT_OK);
	}
}

CloudRegister.java

private GoogleCloudMessaging gcm;

	public void setupGoogleCloudMessaging() {
		new AsyncTask<Void, Void, Boolean>() {
			private String registrationId;

			@Override
			protected Boolean doInBackground(Void... params) {
				try {
					if (gcm == null) {
						gcm = GoogleCloudMessaging.getInstance(Home.this);
					}
					
					registrationId = gcm.register(SENDER_ID);
				        // save registration id to Shared preferences.
					return true;
				} catch (IOException ex) {
					return false;
				}
			}

			@Override
			protected void onPostExecute(Boolean result) {
				// Do something if registered successfully.
			}

		};

	}