Java系列-Handler + Thread用法

import android.os.Handler;
import android.os.Looper;
import android.os.Message;

import androidx.annotation.NonNull;

import java.lang.ref.WeakReference;

public class MyHandlerThread implements Runnable {

    /**
     * mReadyFence对象通过synchronized保护mReady/mRunning两个变量
     */
    private Object mReadyFence = new Object();
    private boolean mReady;
    private boolean mRunning;

    private MyHandler mHandler;

    public void start() {
        synchronized (mReadyFence) {
            if (mRunning) {
                return;
            }
            mRunning = true;
            new Thread(this, "TestThread").start();
            while (!mReady) {
                try {
                    mReadyFence.wait();
                } catch (InterruptedException ie) {
                    // ignore
                }
            }
        }
        mHandler.sendEmptyMessage(MSG_START);
    }

    public void stop() {
        mHandler.sendEmptyMessage(MSG_STOP);
        mHandler.sendMessage(mHandler.obtainMessage(MSG_QUIT));
    }

    public boolean isRunning() {
        synchronized (mReadyFence) {
            return mRunning;
        }
    }

    public void frameAvailable() {
        synchronized (mReadyFence) {
            if (!mReady) return;
        }
        mHandler.sendEmptyMessage(MSG_FRAME);
    }

    @Override
    public void run() {
        Looper.prepare();
        synchronized (mReadyFence) {
            mHandler = new MyHandler(this);
            mReady = true;
            mReadyFence.notifyAll();
        }
        Looper.loop();
        synchronized (mReadyFence) {
            mReady = mRunning = false;
            mHandler = null;
        }
    }

    private final static int MSG_START = 1;
    private final static int MSG_STOP = 2;
    private final static int MSG_FRAME = 3;
    private final static int MSG_QUIT = 4;
    private class MyHandler extends Handler {
        private WeakReference<MyHandlerThread> mWeakThread;

        public MyHandler(MyHandlerThread thread) {
            mWeakThread = new WeakReference<MyHandlerThread>(thread);
        }

        @Override
        public void handleMessage(@NonNull Message msg) {
            switch (msg.what) {
                case MSG_START:
                    handleStart();
                    break;
                case MSG_STOP:
                    handleStop();
                    break;
                case MSG_FRAME:
                    handleFrame();
                    break;
                case MSG_QUIT:
                    Looper.myLooper().quitSafely();
                    break;
            }
        }
    }

    private void handleStart() {

    }

    private void handleStop() {

    }

    private void handleFrame() {

    }
}