Explanation and examples of using HandlerThread

HandlerThread is a thread class with a Looper, extending from the Thread class and implementing the Runnable interface. Its main purpose is to make it easier to execute a series of tasks in the background thread, and communicate with the main thread through a Handler.

The principle of HandlerThread is as follows:

1. Create a Looper object within the HandlerThread and initialize it using the Looper.prepare() method.
2. Call the Looper.loop() method to start the message loop mechanism of Looper, allowing the HandlerThread to process messages.
3. Create a Handler object within the HandlerThread, which is bound together with the HandlerThread and can process messages within the HandlerThread.

The use of examples is as follows:

public class MyHandlerThread extends HandlerThread {
    private Handler mHandler;

    public MyHandlerThread(String name) {
        super(name);
    }

    @Override
    protected void onLooperPrepared() {
        super.onLooperPrepared();
        mHandler = new Handler(getLooper()) {
            @Override
            public void handleMessage(Message msg) {
                // 在HandlerThread中处理消息
                // ...
            }
        };
    }

    public void sendMessage(int what) {
        if (mHandler != null) {
            mHandler.sendEmptyMessage(what);
        }
    }
}

Utilize MyHandlerThread in the main thread.

MyHandlerThread handlerThread = new MyHandlerThread("MyHandlerThread");
handlerThread.start();

// 发送消息到HandlerThread中处理
handlerThread.sendMessage(1);

In MyHandlerThread, we override the onLooperPrepared() method to initialize a Handler object and bind it with the HandlerThread. This allows us to call sendMessage() externally to send messages to the HandlerThread for processing.