progressDialog in AsyncTask

class QueryBibleDetail extends AsyncTask<Integer, Integer, String>{
        private Activity activity;
        private ProgressDialog dialog;
        private Context context;

        public QueryBibleDetail(Activity activity){
            this.activity = activity;
            this.context = activity;
            this.dialog = new ProgressDialog(activity);
            this.dialog.setTitle("查询经文");
            this.dialog.setMessage("正在查询："+tome+chapterID+":"+sectionFromID+"-"+sectionToID);
            if(!this.dialog.isShowing()){
                this.dialog.show();
            }
        }

        @Override
        protected String doInBackground(Integer... params) {
            Log.d(TAG,"经文doInBackground");
            publishProgress(params[0]);

            if(sectionFromID > sectionToID){
                return "";
            }

            String queryBible = "action=query_bible&article="+chapterID+"&id="+tomeID+"&verse_start="+sectionFromID+"&verse_stop="+sectionToID+"";
            try{
                String bible = (Json.getRequest(HOST+queryBible)).trim();
                bible = android.text.Html.fromHtml(bible).toString();
                return bible;
            }catch(Exception e){
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(String bible){
            Log.d(TAG,"经文onPostExecute");
            TextView bibleBox = (TextView) findViewById(R.id.bibleBox);
            bibleBox.setText(bible);
            this.dialog.dismiss();
        }
    }