The Local Broadcast Manager technical principles in the Android Support Library Cure

Shrown in the Local Broadcast Manager technical principles in the Android SUPPORT Library introduction: In the development of Android, Local Broadcast Manager is a powerful tool in the Android Support library to achieve internal communication and message transmission.This article will introduce the technical principles of Local Broadcast Manager, and help readers better understand their usage methods and internal mechanisms through the Java code example. 1. What is Local Broadcast Manager Local Broadcast Manager is a lightweight message mechanism provided by the Android Support library.It allows internal components (such as Activity, Fragment, Service, etc.) to communicate and receive broadcasts to communicate without the need to use system -level broadcast mechanisms.Compared to Global Broadcast, Local Broadcast has higher security and efficiency, which can help developers better control the scope of transmission of messages. Second, the core category and methods of Local Broadcast Manager The core category of Local Broadcast MANAGER is LocalBroadCastManager. It is a singles instance that is used to manage and distribute local broadcasts.Below is some of the core methods provided by Local Broadcast Manager: 1. GetinStance (Context Context): Get a single example of LocalBroadCastManager. 2. RegisterReceiver (BroadcastReceiver Receiver, IntentFilter Filter): Register a broadcast receiver. 3. UnregisterReceiver (BroadcastReceiver Receiver): Cancel a registered broadcast receiver. 4. Sendbroadcast (Intent Intent): Send a local broadcast. How to use Local Broadcast Manager The following is a simple example to introduce how to use Local Broadcast Manager. 1. Create a broadcast receiver (BroADCASTRECEIVER): public class MyBroadcastReceiver extends BroadcastReceiver { @Override public void onReceive(Context context, Intent intent) { // Process the receiving broadcast message String message = intent.getStringExtra("message"); Log.d("MyBroadcastReceiver", "Received message: " + message); } } 2. Register and send broadcast messages: // Register a broadcast receiver MyBroadcastReceiver receiver = new MyBroadcastReceiver(); LocalBroadcastManager.getInstance(this).registerReceiver(receiver, new IntentFilter("my_local_broadcast")); // Send broadcast message Intent intent = new Intent("my_local_broadcast"); intent.putExtra("message", "Hello, Local Broadcast!"); LocalBroadcastManager.getInstance(this).sendBroadcast(intent); 3. Cancel the registered broadcast receiver: LocalBroadcastManager.getInstance(this).unregisterReceiver(receiver); Fourth, the technical principles of Local Broadcast Manager The core mechanism of Local Broadcast MANAGER to implement the internal communication of the application is to use a HashMap to maintain the mapping relationship between the broadcast receiver and the corresponding IntentFilter.When the registerReceiver method is called to register a broadcast receiver, the Local Broadcast Manager adds the receiver and the specified IntentFilter to the HashMap. When sending a broadcast, Local Broadcast Manager traverses hashmap, finds all the radio receivers that match the INTENT, and call its ONREIVE method in turn. Since the Local Broadcast Manager only transmits only information inside the application, it does not need to use the Broadcast mechanism of the Android system, which also improves performance and security. Summarize: Through Local Broadcast Manager in the Android Support library, developers can easily implement internal communication and message transmission.This article briefly introduces the method and internal mechanism of Local Broadcast Manager, and provides the corresponding Java code example to help readers better understand.In actual development, reasonable use of Local Broadcast Manager can improve the readability and maintenance of code, and can also improve the performance and security of the application.