android 中Handle弱引用使用

private MyHandler handlerData = new MyHandler(this);

 static class MyHandler extends Handler {
        private WeakReference weakReference;

        MyHandler(PersonalActivity fragmentActivity) {
            weakReference = new WeakReference(
                    fragmentActivity);
        }

        @Override
        public void handleMessage(Message msg) {
            final PersonalActivity activity = weakReference.get();
            switch (msg.what) {
                case 100:
                    String data = (String) msg.obj;
                    final String response_body = data.substring(1, data.length() - 1);
                    activity.getNetQYData(response_body);
                    break;

            }
        }
    }

Message msg = handlerData.obtainMessage();
        msg.what = 100;
        msg.obj = str;
        handlerData.sendMessage(msg);