The technical principles of Android support libraries in the Java class library (Technical Principles of Local Broadcast Manager in Java Class Libraares of Android Support Library)

The technical principles of Android support library local radio manager in the Java class library In the Android support library in the Java class library, Local Broadcast Manager is a powerful tool for sending and receiving broadcast messages inside the application.Local broadcast managers have more efficient and safer characteristics compared to Global Broadcast Manager. 1. Overview of the local broadcast manager Local broadcasting managers are used inside the application, which allows efficient communication between application components without considering interaction with other applications.Local broadcast manager is a component provided in the Android support library, which is used to replace the global broadcast manager to provide better performance and privacy protection. The main features of local broadcasting managers include: 1. High -efficiency: Local broadcasting managers pass on broadcast messages inside the application, and no system -level broadcasts are required, thereby reducing system expenses; 2. Privacy protection: The local broadcast manager can only be received by the internal components. Other applications cannot monitor or receive these broadcast messages, providing higher privacy protection; 3. Safety: Local broadcasting managers filter and control through INTENT and permissions to ensure that only components with corresponding permissions can receive broadcast messages. 2. Principles of the implementation of local broadcasting managers The implementation principle of the local broadcast manager involves the following key components and concepts: 1. LocalBroadCastManager class: This is the core category of local broadcasting managers, responsible for managing the sending and receiving of broadcasting.It is a singles class that obtains an instance through the getInstance () method. 2. BroadcastReceiver class: This is a component that receives internal receiving broadcast messages.Developers need to inherit the BroadcastReceiver class and implement the onReceive () method to process the receiving broadcast messages. 3. Intent class: This is a class used to create and conveys broadcast messages.Intent objects can carry some additional data so that the receiver can understand and process broadcast messages. 4. IntentFilter class: This is a class that specifies the type of broadcast message that can be received by a receiver.You can add multiple ACTION to listen to multiple broadcast messages through the addaction () method. The following is a sample code using a local broadcast manager: 1. In the component of the sending broadcast: // Obtain examples of local broadcast manager LocalBroadcastManager localBroadcastManager = LocalBroadcastManager.getInstance(context); // Create a new Intent object Intent intent = new Intent("com.example.MY_ACTION"); // Add additional data intent.putExtra("data", "Hello, LocalBroadcastManager!"); // Send local broadcast localBroadcastManager.sendBroadcast(intent); 2. In the component of receiving broadcast: // Create a broadcast receiver BroadcastReceiver broadcastReceiver = new BroadcastReceiver() { @Override public void onReceive(Context context, Intent intent) { // Process the receiving broadcast message String data = intent.getStringExtra("data"); Toast.makeText(context, data, Toast.LENGTH_SHORT).show(); } }; // Create an IntentFilter object IntentFilter intentFilter = new IntentFilter("com.example.MY_ACTION"); // Register a broadcast receiver localBroadcastManager.registerReceiver(broadcastReceiver, intentFilter); In the above code, the component sent to the GetInstance () method of LocalBroadCastManager obtained the instance of the local broadcast manager through LocalBroadCastManager.Then create an INTENT object to specify the sending message type, and add additional data through the Putextra () method.Finally, call the Sendbroadcast () method to send a broadcast. The component of the receiving broadcast also obtains the instance of the local broadcast manager through the getInstance () method.Create a broadcast receiver and rewrite the ONREIVE () method to process the receiving broadcast messages.Then, create an IntentFilter object to specify the type of broadcast message type that the receiver can receive, and call the registerReceiver () method to register the broadcast receiver. Summarize: Local broadcasting managers are a powerful tool in the Android support library to transmit and receive broadcast messages within the application.By using a local broadcast manager, the efficiency and privacy protection of radio communication can be improved.In terms of implementation, local broadcasting managers use several key components, such as LocalBroadCastmanager, BroadcastReceiver, Intent, and IntentFilter to achieve broadcasting and receiving.The above example code shows how to use the local broadcast manager to send and receive broadcast messages in the application.