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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 .

When does Broadcast Receiver start?

I'm new to android and trying to build a simple app which needs to listen for incoming sms. I know that I need to use the BroadcastReceiver class and I also know how to make my own broadcast receiver. But how do I start it? Does it start automatically if I set the code for it in the manifest? The app just has the Main activity, do I need to somehow add a broadcast receiver in the onCreate of this activity? I searched for an answer, but it's still not clear to me. I know it's not nice to ask, but it would be great if you can share some sample code. Thanks!

If you declare the receiver within your AndroidManifest.xml, then you shouldn't need to do anything more. When a broadcast gets sent, the Android system will look through all installed apps and notify each app that has declared the appropriate Receiver in its manifest, starting the app in the process if necessary. For most cases, such as SMS, that is how you want to declare receivers, because most broadcasts are sent with the intent that you want to open your app when its not currently running to react to the broadcast.
Alternatively, you may declare the broadcast within a running activity, which may be useful if you want the broadcast to directly update the UI in your running app.
BroadcastReceiver Documentation

How broadcast receiver works in Android

I have a question about BroadcastReceiver in Android, say, about system broadcast receiver BOOT_COMPLETED. If I have written a listener to Broadcast after system is booted and installed it. How the android system would know that it has to notify my application, since my application is not running but just installed? Is it that, all BroadcastReceiver derived classes are always in the memory (or system loads them in the memory after bootup) and whenever any broadcast happens, all relevant application can receive it.
Thanks
Braj

When the broadcast BOOT_COMPLETED is sent, the Android system checks the manifests of loaded apps to see if anything is meant to handle that message. The same is true for implicit intents, and all broadcasts.
Manifests are public facing and allows the system to know what your app can and will do.

Difference between Service and Broadcast receivers in android

I want to know the difference between services and broadcast receivers, can anyone point out an example that can be observed on android mobile devices.
Thanks

Service: If you want to do something in background , this will be running always in background even if the application closed. You can create this in separate process and also you can give your service to other app if you want. Downloading any content or Music is good example
Broadcast Reciever: 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
Here is good article : Service and BroadcastReceiver

Service is used when you want to do something in background, any long running process can be done using Service in Background. For example, you want to play music when your application gets close. In that case service will be running in background with music.
Example of Service
BroadcastReceiver is used when you want to fire some stuff or code during some event. For example, event can be on Boot of Device. If you want to perform something when device Boots, date and time changed etc...
Example of BroadcastReceiver

I think of it possibly a different way. A Service receives intents that were sent specifically to your application, just like an Activity. A Broadcast Receiver receives intents that were broadcast system-wide to all apps installed on the device.
(The reason I say a Service is a bit like an Activity is that: You wouldn't broadcast a message saying "start Activity MyActivity" across all apps installed on the device. It is only for your specific app.)
Of course, as others mentioned, a Service can continue running in the background, whereas a Broadcast Receiver should finish quickly (e.g. if it is running for more than 5 seconds it may be killed by the OS). The Broadcast Receiver can still run in the background (when app is closed) under certain circumstances. For this, it's worth mentioning that there are actually two types of Broadcast Receivers - Manifest-declared, and Context-registered. They have different lifespans and restrictions - the former can receive broadcasts in the background with certain restrictions, while the latter cannot receive broadcasts in the background (app must be running and active) but has no restrictions on the types of intents that can be received.
Both services and broadcast receivers must be specifically invoked (via an intent), but for services this is usually a specific call (e.g. when your app is started or when the user clicks some button) whereas for broadcast receivers they don't need to be explicitly started as they will start anyway when a relevant broadcast is made.
Here's how I would think of it:
Type
Displays UI?
Can continue running for a long time when app is closed?
Can receive intents when app is closed?
Intents must specifically target your app?
Restricted list of intents that can be specified?
Activity
Yes
No
Yes
Yes
No
Service
No
Yes
Yes
Yes
No
Manifest-declared Broadcast Receiver
No
No
Yes
No
Yes1
Context-registered Broadcast Receiver
No
No
No
No
No
1: Only if you target Android 8.0 or above. The restrictions are not applied if the intent specifically targets your app. The restricted list of intents can be found here.

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.