Android HandlerThread的使用及原理详解

public class MainActivity extends AppCompatActivity {
 
  private TextView tvMain;
 
  private HandlerThread mHandlerThread;
  //子线程中的handler
  private Handler mThreadHandler;
  //UI线程中的handler
  private Handler mMainHandler = new Handler();
 
  //以防退出界面后Handler还在执行
  private boolean isUpdateInfo;
  //用以表示该handler的常熟
  private static final int MSG_UPDATE_INFO = 0x110;
 
  @Override
  protected void onCreate(Bundle savedInstanceState)
  {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    tvMain = (TextView) findViewById(R.id.tv_main);
 
    initThread();
  }
 
 
  private void initThread()
  {
    mHandlerThread = new HandlerThread("check-message-coming");
    mHandlerThread.start();
 
    mThreadHandler = new Handler(mHandlerThread.getLooper())
    {
      @Override
      public void handleMessage(Message msg)
      {
        update();//模拟数据更新
 
        if (isUpdateInfo)
          mThreadHandler.sendEmptyMessage(MSG_UPDATE_INFO);
      }
    };
 
  }
 
  private void update()
  {
    try
    {
      //模拟耗时
      Thread.sleep(2000);
      mMainHandler.post(new Runnable()
      {
        @Override
        public void run()
        {
          String result = "每隔2秒更新一下数据：";
          result += Math.random();
          tvMain.setText(result);
        }
      });
 
    } catch (InterruptedException e)
    {
      e.printStackTrace();
    }
 
  }
 
  @Override
  protected void onResume()
  {
    super.onResume();
    //开始查询
    isUpdateInfo = true;
    mThreadHandler.sendEmptyMessage(MSG_UPDATE_INFO);
  }
 
  @Override
  protected void onPause()
  {
    super.onPause();
    //停止查询
    //以防退出界面后Handler还在执行
    isUpdateInfo = false;
    mThreadHandler.removeMessages(MSG_UPDATE_INFO);
  }
 
  @Override
  protected void onDestroy()
  {
    super.onDestroy();
    //释放资源
    mHandlerThread.quit();
  }
}

public class HandlerThread extends Thread {
  int mPriority;
  int mTid = -1;
  Looper mLooper;
 
  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() {
    mTid = Process.myTid();
    Looper.prepare();
    synchronized (this) {
      mLooper = Looper.myLooper();
      notifyAll();
    }
    Process.setThreadPriority(mPriority);
    onLooperPrepared();
    Looper.loop();
    mTid = -1;
  }
 
 
  public Looper getLooper() {
    if (!isAlive()) {
      return null;
    }
 
    // If the thread has been started,wait until the looper has been created.
    synchronized (this) {
      while (isAlive() && mLooper == null) {
        try {
          wait();
        } catch (InterruptedException e) {
        }
      }
    }
    return mLooper;
  }
 
 
  public boolean quit() {
    Looper looper = getLooper();
    if (looper != null) {
      looper.quit();
      return true;
    }
    return false;
  }
 
 
  public boolean quitSafely() {
    Looper looper = getLooper();
    if (looper != null) {
      looper.quitSafely();
      return true;
    }
    return false;
  }
 
 
  public int getThreadId() {
    return mTid;
  }
}