/*从数据库读取某省下所有的城市*/
  public List<Country> loadCountries(int cityId) {
    List<Country> list = new ArrayList<Country>();
    Cursor cursor =
        db.query(
            "Country",
            null,
            "city_id = ?",
            new String[] {String.valueOf(cityId)},
            null,
            null,
            null);
    if (cursor.moveToFirst()) {
      do {
        Country country = new Country();
        country.setId(cursor.getInt(cursor.getColumnIndex("id")));
        country.setCountryname(cursor.getString(cursor.getColumnIndex("country_name")));
        country.setCountrycode(cursor.getString(cursor.getColumnIndex("country_code")));
        country.setCityid(cityId);
        list.add(country);
      } while (cursor.moveToNext());
    }

    if (cursor != null) {
      cursor.close();
    }

    return list;
  }
 /*将country数据存储到数据库*/
 public void savecountry(Country country) {
   if (country != null) {
     ContentValues val = new ContentValues();
     val.put("country_name", country.getCountryname());
     val.put("country_code", country.getCountrycode());
     val.put("city_id", country.getCityid());
     db.insert("Country", null, val);
   }
 }