private void readCurrentUser() {
    dbHelper = OpenHelperManager.getHelper(getApplicationContext(), WTDbHelper.class);
    RuntimeExceptionDao<User, String> userDao = dbHelper.getUserDao();

    SharedPreferences sp =
        getApplicationContext().getSharedPreferences("SettingInfo", MODE_PRIVATE);

    mUser = userDao.queryForId(sp.getString("CurrentSchoolNumber", ""));
  }
  public void updateUserDB(String jsonStr) throws Exception {
    JSONObject data = new JSONObject(jsonStr);
    JSONObject userStr = data.getJSONObject("User");

    Gson gson = new Gson();

    User user = gson.fromJson(userStr.toString(), User.class);

    // 写入user到数据库
    dbHelper = OpenHelperManager.getHelper(getApplicationContext(), WTDbHelper.class);
    RuntimeExceptionDao<User, String> userDao = dbHelper.getUserDao();
    userDao.update(user);
  }