/*
 将County实例存储到数据库
  */
 public void saveCounty(County county) {
   if (county != null) {
     ContentValues values = new ContentValues();
     values.put("county_name", county.getCountyName());
     values.put("county_code", county.getCountyCode());
     values.put("city_id", county.getCityId());
     db.insert("County", null, values);
   }
 }
  /*
  从数据库读取某省下所有的城市信息
   */
  public List<County> loadCounties(int cityId) {
    List<County> list = new ArrayList<County>();
    Cursor cursor =
        db.query(
            "County", null, "city_id=?", new String[] {String.valueOf(cityId)}, null, null, null);
    if (cursor.moveToFirst()) {
      do {
        County county = new County();
        county.setId(cursor.getInt(cursor.getColumnIndex("id")));
        county.setCountyName(cursor.getString(cursor.getColumnIndex("county_name")));
        county.setCountyCode(cursor.getString(cursor.getColumnIndex("county_code")));
        county.setCityId(cityId);

        list.add(county);
      } while (cursor.moveToNext());
    }

    return list;
  }