public static JSONArray getGuanLiJson(Connection connection,String tablenameString,String field,String idString) throws Exception {

        JSONObject jsonObject=new JSONObject();

        JSONArray jsonArray=new JSONArray();

        String sqlString="select  "+field+" from "+tablenameString;

        PreparedStatement preparedStatement=connection.prepareStatement(sqlString);

        ResultSet resultSet=preparedStatement.executeQuery();

        while(resultSet.next()){

            jsonObject.put(idString, resultSet.getString(field));

            jsonArray.add(jsonObject);

        }

        return jsonArray;

    }