我开始AsyncTask加载一个需要一些时间的文件。为了通知用户我正在显示一个ProgressDialog,但是如果我触摸屏幕,它会ProgressDialog立即关闭。这可能是什么原因?
 public LoadTask(Activity activity, FaceRecognizer recognizer,SecretKey key) {
    this.key = key;     
    this.recognizer = recognizer;       
    dialog = new ProgressDialog(activity);
}
@Override
protected void onPreExecute() {
    dialog.setMessage("Loading the recognizer...");
    dialog.show();
}
@Override
protected Boolean doInBackground(Void... params) {
    recognizer.load(key);
    return null;
}
@Override
protected void onPostExecute(Boolean result) {
    if (dialog.isShowing()) {
        dialog.dismiss();
    }