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Android app which only have a service starts in the background can't receive broadcast message

I'm having a problem about android BroadcastReceiver. It's the first time for asking questions on stack overflow, and my English is bad. So I describe the question in Chinese again in the end!
I want my app can automatic run when the android system starts.First I register a BroadcasetReceiver which can receive the BOOT_COMPLETED message in the static way (in the AndroidManifest.xml).This BroadcastReceiver works well. The BroadcastReceiver needs to start a service, the service is running all the time, and it registers another BroadcastReceiver which can receive the CONNECTIVITY_ACTION message in the dynamic way.But when the networks changes, the app can't receive the CONNECTIVITY_ACTION message in the HUAWEI pad only when the app starts the main Activity.(It can works well in the HUAWEI phone).
note：The BroadcastReceiver which receives the CONNECTIVITY_ACTION message must be register in the dynamic way. Because the app need to unregister it sometimes.
(写了一个开机自动启动的程序，开机启动一个service，这个service一启动就动态的注册一个监听网络变化的broadcastreceiver，可是在华为的pad上，这个broadcastreceiver始终不能接收到网络状态变化的广播消息，除非启动主Activity，但是华为手机没有这个问题！)

1、Your phone's Android version maybe not same to your pad's;
2、I suggest you register broadcast in static way;
3、Are you sure this service started after reboot? you can write a log .

Android: How to start activity when phone is sleeping, similar to Viber incomming call activity

I am developing an app and this app needs to give a clear indication to the user when some event happens.
Only thing I could do until now is giving a notification in the notification area. But, I need to give a more visible notification, similar to the behavior when phone is ringing in an incoming call.
As I can understand, the reason why android is only allowing apps to give a notification is to prevent apps from disturbing the user. But, this app I am developing plays a vital role in the job of the user, so I don't think it is inappropriate to give a such strong notification.
I know it should be doable since apps like Viber can start an activity similar to a incoming phone call, even when the device is sleeping.
Does anyone know how to get this done?

Register a broadcast receiver, and add a custom action to it say CustomAction.Instead of showing notification, throw a broadcast and add CustomAction via intent filter.
Now in the onReceive method of broadcast listener, check
if(intent.getAction.equals("CustomAction"))Intent i = new Intent(context, YourActivity);
context.startActivity(i);
Sorry for not a formatted answer, I'm driving, will update it later for more clarification.
Update
Register broadcast receiver in a sticky service. So that service can be started automatically if killed and register broadcast register again.
Don't forget to unregister broadcast receiver in onDestroy() method of service and also in YourActivity when you purpose is resolved.

Just adding a sticky service (which does nothing) fixed the issue. Adding the service prevented the process getting killed when user exits the app and removes it from recent app list.
Because of the service, the app process is running even when a no UI is visible. In this state, if an activity is shown from the GCM service, it gets shown.

You can trigger a broascast as Vinay mentioned. If it still does not work, try using wake-locks. These wake-locks help in waking the device when it is in sleep mode. It will act like force wake and after calling wake-locks, you can perform your actions.
Hope it helped..
Thanks.

What is the difference between Broadcast Receiver and service?

I wrote program for broadcast receiver and service, but i confused in the manifest file there is some ground work to register service and receiver, will any one give me clear idea about this? Thanks in advance.

Service
It is used when you want to do something in background, any long running process can be done using Service in Background.
This will be running always in background even if the application closed
For example, you want to play music when your application gets close. In that case service will be running in background with music.
BroadcastReceiver
It is used when you want to fire some stuff or code during some event. For example, event can be on Boot of Device.
Usually system will send some info which can be recieved by your app if you would wish to ,by registering. And you can do something what you want when that thing happens by using onReceive method. Example is the system will send BroadcastReceiver when new sms arrives or Booting done
for example, If you want to perform something when device Boots, date and time changed etc.

A service is used to perform long running operations without user interaction or to supply functionality to other applications.
A Service needs to be declared in the AndroidManifest.xml via
a <service android:name="yourclasss"> </service> and the implementing class
must extend the Service class or one of its subclasses.
To start Services automatically after the Android system starts you can register
a BroadcastReceiver to the Android android.intent.action.BOOT_COMPLETED system
event. This requires the android.permission.RECEIVE_BOOT_COMPLETED permission.
For more details, check this http://www.vogella.com/articles/AndroidServices/article.html#pre_broadcastreceiver

A broadcast receiver is an Android component which allows to register for system or application events. All registered receivers for an event will be notified by Android once this event happens.
A Service is an application component representing either an application's desire to perform a longer-running operation while not interacting with the user or to supply functionality for other applications to use.
It'll be very long to explain it all here
I've got 2 great tutorial links from vogella
Broadcast Receiver
Service
if you have further question after reading the tutorial feel free to ask me in the comment :)

What is BroadcastReceiver and when we use it?

What is a BroadcastReceiver? What are its uses and how can I use it?

Start by reading the documentation. Also, copying from Application Fundamentals:
Broadcast receivers
A broadcast receiver is a component that responds to system-wide
broadcast announcements. Many
broadcasts originate from the
system—for example, a broadcast
announcing that the screen has turned
off, the battery is low, or a picture
was captured. Applications can also
initiate broadcasts—for example, to
let other applications know that some
data has been downloaded to the device
and is available for them to use.
Although broadcast receivers don't
display a user interface, they may
create a status bar notification to
alert the user when a broadcast event
occurs. More commonly, though, a
broadcast receiver is just a "gateway"
to other components and is intended to
do a very minimal amount of work. For
instance, it might initiate a service
to perform some work based on the
event.
A broadcast receiver is implemented as a subclass of
BroadcastReceiver and each broadcast
is delivered as an Intent object. For
more information, see the
BroadcastReceiver class.
Finally, read in Common Tasks how you can utilize BroadcastReceivers to listen for messages and set alarms.

A broadcast is generated by android on occurrence of some action , BroadcastReceiver class enables the developer to handle the situation on occurence of the event/action . Action can be arrival of msg or call , download complete , boot completed , etc.

Broadcast Receivers simply respond to broadcast messages from other applications or from the system itself. These messages are sometime called events or intents. For example, applications can also initiate broadcasts to let other applications know that some data has been downloaded to the device and is available for them to use, so this is broadcast receiver who will intercept this communication and will initiate appropriate action.

I like this slide, because it focuses on Broadcast Receiver and offers simple description. The minor problem is that the updated date was a little bit old ( in 2011 ).
Link
Android Application Component: BroadcastReceiver Tutorial
(retrieved from the slide)
Broadcast Receiver
Receives and Reacts to broadcast Intents
No UI but can start an Activity
Extends the BroadcastReceiver Base Class

BroadCastReciever is an Android Component that helps you to know handle registered System Events or Application Events.
For Example:
System Events Such us : the screen has turned off, the battery is low, or a picture was captured.
Applications can also initiate broadcasts—for example, to let other applications know that some data has been downloaded to the device and is available for them to use... etc

In simple terms
A broadcast receiver is basically an interface that you can implement so that your app can subscribe to system changes like when the system has finished booting, or a charger is connected/disconnected or airplane mode is switched on/off etc.

Launch app on incoming call (android)

I have an app on Android that reacts to incoming calls.
Now, since the OS shuts my app down whenever it want,
I need a way to to listen to the incoming calls and launch the app when it happens.
Will a BroadcastReceiver help? (just like launching on device restart)
Any idea?
thanks!

I think you have answered your own question. This is just the sort of thing a broadcast receiver is meant for. If the receiver is registered in your manifest then the application does not have to be running.
It will be automatically started when a matching intent is broadcast. Typically the response will be to update content or activities, make notifications with the Notification manager or launch/manipulate services.
Note that there is a 5 second execution limit in the BroadcastReceiver onReceive handler to ensure you do not try to do any 'heavy lifting' in it. Exceed this and a force close dialog will be displayed.

Yes a BroadcastReceiver would to the job as it will fire even you app is not running.