Analysis of the Technical Principles of Local Broadcast Manager in Android Support Library

The local radio manager in the Android support library is a tool for sending and receiving local broadcasts.Local broadcasting is an internal application communication mechanism that conveys messages between components in the same application.Different from the global broadcasting, local broadcasts are only transmitted inside the application and can provide higher security and performance.In this article, we will explore the technical principles of the local radio manager in the Android support library. The local broadcast manager is implemented by the `LocalBroadCastManager` class in the Android support library.It provides a set of methods to register, cancel and send local broadcasts.Here are some commonly used methods: -`registerReceiver ()`: You can register a broadcast receiver through this method to receive local broadcasts.Need to pass an instance of a `BroadcastReceiver` and an object of a` IntentFilter` to specify which type of broadcasts to receive. -`unregisterReceiver ()`: Used to cancel the broadcast receiver registered before registration. -`andbroadcast ()`: Used to send a local broadcast to all registered broadcast receivers.You need to pass a `Intent` object to specify the type and additional data you need to send. The implementation principles of local broadcasting managers mainly depend on two core components: 'ReceiverRecord` and `BroadcastRecord`. The `ReceiverRecord` class is used to save information about the registered broadcast receiver.Each registered broadcast receiver is encapsulated into an object of `ReceiverRecord` and stored in a` HashMap`.The key of this `HashMap` is an object of` BroadcastReceiver`, and the value is a `ArrayList`, which inside the object registered by the receiver.In this way, you can find the corresponding `IntentFilter`. `Broadcastrecord` class is used to save information about the broadcast to be sent.Whenever the method is called to send a broadcast when calling the method of `Sendbroadcast ()`, the broadcast will be encapsulated into a `BroadCastRecord` object and save it in a queue.The operation of the sending broadcast is performed in a cycle, which traverses the queue to be sent to the broadcast. In each round of the cycle, each broadcast in the queue will be processed in turn, and it will be sent to all matching broadcast receivers. The execution process of the entire process is as follows: 1. Call the `Sendbroadcast () method to send a broadcast. 2. Create an object of `BroadcastRecord` and save the broadcast -related information in it. 3. Add the `Broadcastrecord` object to the broadcast queue to be sent. 4. Execute a cycle and traverse the broadcast queue. 5. In every round of the cycle, take out the next broadcast in the queue. 6. The registered broadcast receiver traversed in the traversing in the `LocalBroadCastManager` and find all the matching broadcast receivers. 7. For each matching radio receiver, create an object of `BroadCastReceiver` and call its` ``) method to handle the broadcast. 8. Remove the processed radio receiver from the radio queue to be sent. By using the `LocalBroadCastManager` class, we can easily implement the internal communication mechanism of the application.It provides a safe and efficient way to send and receive local broadcasts.Using local broadcasts can effectively reduce the range of broadcasting, improve system performance, and does not cause any security problems. The following is a simple example of using a local broadcast manager: // Create a broadcast receiver BroadcastReceiver receiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { // Treat the receiving broadcast } }; // Create an IntentFilter object IntentFilter filter = new IntentFilter(); filter.addAction("com.example.MY_ACTION"); // Register a broadcast receiver LocalBroadcastManager.getInstance(context).registerReceiver(receiver, filter); // Send broadcast Intent intent = new Intent("com.example.MY_ACTION"); LocalBroadcastManager.getInstance(context).sendBroadcast(intent); // Cancel the registered broadcast receiver LocalBroadcastManager.getInstance(context).unregisterReceiver(receiver); In the above examples, we created a broadcast receiver and specifically specify the receiving `com.example.my_Action" type of broadcast through the `IntentFilter` object.Then, we use instances of the `LocalBroadCastManager` to register a broadcast receiver, send broadcasting and cancel the registered broadcast receiver.In this way, a simple process of sending and receiving the local broadcasting process is completed. In summary, the local radio manager in the Android support library uses the registered broadcast receiver and the broadcast of the registered broadcast receiver and the broadcast to be sent.By using the `LocalBroadCastManager` class, we can easily send and receive local broadcasts to provide higher security and performance.