AsyncQueryHandler

内部使用一个HanderThread以及与之挂钩的Handler来处理消息

    public AsyncQueryHandler(ContentResolver cr) {

        super();
        mResolver = new WeakReference<ContentResolver>(cr);
        synchronized (AsyncQueryHandler.class) {
            if (sLooper == null) {
                HandlerThread thread = new HandlerThread("AsyncQueryWorker");
                thread.start();


                sLooper = thread.getLooper();
            }
        }
        mWorkerThreadHandler = createHandler(sLooper);
    }