Thread、Handler和HandlerThread关系详解

private HandlerThread mHandlerThread;
......
mHandlerThread = new HandlerThread("HandlerThread");
handlerThread.start();

 final Handler handler = new Handler(mHandlerThread.getLooper()){
   @Override
   public void handleMessage(Message msg) {
    System.out.println("收到消息");
   }
  };

 new Thread(new Runnable() {
   @Override
   public void run() {
    try {
     Thread.sleep(1000);//模拟耗时操作
     handler.sendEmptyMessage(0);
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
   }
  }).start();

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

 protected void onLooperPrepared() {
 }
 @Override
 public void run() {
  mTid = Process.myTid();
  Looper.prepare();
  synchronized (this) {
   mLooper = Looper.myLooper();//生成Looper
   notifyAll();
  }
  Process.setThreadPriority(mPriority);
  onLooperPrepared();//空方法，在Looper创建完成后调用，可以自己重写逻辑
  Looper.loop();//死循环，不断从MessageQueue中取出消息并且交给Handler处理
  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;
 }