public class HandlerThreadActivity extends BaseActivity {
    
    private static final String TAG = "HandlerThreadActivity";

    private Button mStartBtn;
    private Handler mHandler;
    private HandlerThread mHandlerThread;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_handler_thread);
        mStartBtn = findViewById(R.id.start_btn);

        mHandlerThread = new HandlerThread("THREAD_NAME");
        mHandlerThread.start();
        mHandler = new Handler(mHandlerThread.getLooper());

        mStartBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                mHandler.post(new Runnable() {
                    @Override
                    public void run() {
                        Log.d(TAG, Thread.currentThread().getId() + " " + String.valueOf((Looper.myLooper() == Looper.getMainLooper())) + " 任務(wù)：" + this.hashCode());
                        SystemClock.sleep(3000);
                    }
                });
            }
        });
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        mHandlerThread.quit();
    }
}

public class HandlerThread extends Thread {
    int mPriority;
    int mTid = -1;
    Looper mLooper;
    private @Nullable Handler mHandler;

    public HandlerThread(String name) {
        super(name);
        mPriority = Process.THREAD_PRIORITY_DEFAULT;
    }
    
   
    public HandlerThread(String name, int priority) {
        super(name);
        mPriority = priority;
    }
    
   
    protected void onLooperPrepared() {
    }

    @Override
    public void run() {
        // 獲取線程 id
        mTid = Process.myTid();
        //構(gòu)建一個(gè) Looper
        Looper.prepare();
        synchronized (this) {
            mLooper = Looper.myLooper();
            notifyAll();
        }
        //設(shè)置線程優(yōu)先級(jí)
        Process.setThreadPriority(mPriority);
        onLooperPrepared();
        Looper.loop();
        // Looper 循環(huán)
        mTid = -1;
    }
    
     // 獲取當(dāng)前線程的 Looper，
    public Looper getLooper() {
        if (!isAlive()) {
            return null;
        }
       
        synchronized (this) {
            while (isAlive() && mLooper == null) {
                try {
                    wait();
                } catch (InterruptedException e) {
                }
            }
        }
        return mLooper;
    }


     /**
     * @return a shared {@link Handler} associated with this thread
     * @hide 方法隱藏掉，無(wú)法調(diào)用
     */
    @NonNull
    public Handler getThreadHandler() {
        if (mHandler == null) {
            mHandler = new Handler(getLooper());
        }
        return mHandler;
    }

     //線程退出方法，主要是調(diào)用 Looper.quit() 方法，不然一直在循環(huán)
    public boolean quit() {
        Looper looper = getLooper();
        if (looper != null) {
            looper.quit();
            return true;
        }
        return false;
    }

    //同上，不過(guò)這個(gè)方法會(huì)把消息隊(duì)列中的已有消息處理完才會(huì)安全地退出
    public boolean quitSafely() {
        Looper looper = getLooper();
        if (looper != null) {
            looper.quitSafely();
            return true;
        }
        return false;
    }

    public int getThreadId() {
        return mTid;
    }
}