如何从GCM android接收通知？

Question

我正在开发一个应用程序，因为我必须接收来自server.i的通知我正在成功地向我的服务器发送注册ID，但是我无法从gcm server.i获取通知。我是gettin nullpointerexception请告诉我我犯了错误< / p>

我的Broadcatst接收器

     public class GcmBroadcastReceiver  extends WakefulBroadcastReceiver{

    @Override
    public void onReceive(Context context, Intent intent) {
        // TODO Auto-generated method stub
        ComponentName comp = new ComponentName(context.getPackageName(),
                GcmIntentService.class.getName());
        // Start the service, keeping the device awake while it is launching.
        startWakefulService(context, (intent.setComponent(comp)));
        setResultCode(Activity.RESULT_OK);

    }
     }

GcmIntentService

         public class GcmIntentService extends IntentService{
        Context context;
        public static final int NOTIFICATION_ID = 1;
        private NotificationManager mNotificationManager;
        NotificationCompat.Builder builder;
        public static final String TAG = "GCM Demo";

        public GcmIntentService() {
            super("GcmIntentService");
            // TODO Auto-generated constructor stub
        }

        @Override
        protected void onHandleIntent(Intent intent) {
            // TODO Auto-generated method stub
            Bundle extras = intent.getExtras();
            String msg = intent.getStringExtra("message");
            GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(context);
            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());
                    // If it's a regular GCM message, do some work.
                    } else if (GoogleCloudMessaging.
                            MESSAGE_TYPE_MESSAGE.equals(messageType)) {
                        // This loop represents the service doing some work.
                        for (int i=0; i<5; i++) {
                            Log.i(TAG, "Working... " + (i+1)
                                    + "/5 @ " + SystemClock.elapsedRealtime());
                            try {
                                Thread.sleep(500);
                            } catch (InterruptedException e) {
                            }
                        }
                        Log.i(TAG, "Completed work @ " + SystemClock.elapsedRealtime());
                        // Post notification of received message.
                        //sendNotification("Received: " + extras.toString());
                        sendNotification(msg);
                        Log.i(TAG, "Received: " + extras.toString());
                    }
                }
             GcmBroadcastReceiver.completeWakefulIntent(intent);
        }
        private void sendNotification(String msg) {
            mNotificationManager = (NotificationManager)
                    this.getSystemService(Context.NOTIFICATION_SERVICE);

            Intent myintent = new Intent(context, ReceiveActivity.class);
            myintent.putExtra("message", msg);
            PendingIntent contentIntent = PendingIntent.getActivity(context, 0,
                    myintent, PendingIntent.FLAG_UPDATE_CURRENT);

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

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

       }

的ReceiveActivity

   public class ReceiveActivity extends Activity {
    TextView name;
    TextView deal;
    TextView valid;
    TextView address;
    JSONObject json;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_receive);
    Intent intent = getIntent();

    name = (TextView) findViewById(R.id.name);
    deal = (TextView) findViewById(R.id.deal);
    valid = (TextView) findViewById(R.id.valid);
    address = (TextView)findViewById(R.id.address);
    String message = intent.getExtras().getString("message");
    try {
        json = new JSONObject(message);
        String stime = json.getString("name");
        name.setText(stime);

        String slecturename = json.getString("deal");
        deal.setText(slecturename);

        String sroom = json.getString("valid");
        valid.setText(sroom);

        String sfaculty = json.getString("address");
        address.setText(sfaculty);


    } catch (JSONException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    log cat

异常

02-21 12:10:10.679: E/AndroidRuntime(30200): FATAL EXCEPTION: IntentService[GcmIntentService]
02-21 12:10:10.679: E/AndroidRuntime(30200): java.lang.NullPointerException
02-21 12:10:10.679: E/AndroidRuntime(30200):    at android.app.PendingIntent.getActivity(PendingIntent.java:191)
02-21 12:10:10.679: E/AndroidRuntime(30200):    at com.technowellServices.locationfind.GcmIntentService.sendNotification(GcmIntentService.java:74)
02-21 12:10:10.679: E/AndroidRuntime(30200):    at com.technowellServices.locationfind.GcmIntentService.onHandleIntent(GcmIntentService.java:62)
02-21 12:10:10.679: E/AndroidRuntime(30200):    at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:59)
02-21 12:10:10.679: E/AndroidRuntime(30200):    at android.os.Handler.dispatchMessage(Handler.java:99)