java反射返回结果集集合

/**
     * 实例化X实体
     * @param _tableName String 实体对应的数据库表
     * @param _columnNameList ArrayList 实体对应表中的字段列表
     * @param _con Connection 数据库连接
     * @param _entityName String 实体类名（全名 如com.accp.X）
     * @return ArrayList 从数据库中查找到的该实体列表
     */
    public static ArrayList readColumnData(String _tableName,
                                           ArrayList _columnNameList,
                                           Connection _con, String _entityName) {
        ArrayList _list = null;
        try {
            if (_columnNameList == null) {
                _columnNameList = readColumn(_tableName, _con);
            }
            if (_con != null && _columnNameList != null) {
                Statement _sta = _con.createStatement();
                ResultSet _rs = _sta.executeQuery("select * from " + _tableName);
                while (_rs.next()) {
                    if (_list == null) {
                        _list = new ArrayList();
                    }
                    if (_entityName != null) {
                        Class _class = Class.forName(_entityName);
                        Constructor _constructor = _class.getConstructor(null);
                        Object _entity = _constructor.newInstance(null);
                        Field _fields[] = _class.getDeclaredFields();
                        for (int k = 0; k < _fields.length; k++) {
                            Field _field = _fields[k];
                            _field.setAccessible(true);
                            for (int i = 0; i < _columnNameList.size(); i++) {
                                if (_columnNameList.get(i).toString().equals(
                                        _field.getName())) {
                                    Object _obj = _rs.getObject(_columnNameList.
                                            get(i).toString());
                                    if (_obj != null) {
                                        _field.set(_entity, _obj);
                                    } else {
                                        _field.set(_entity, null);
                                    }
                                    break;
                                }
                            }
                        }
                        _list.add(_entity);
                    }
                }
                _sta.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if (_con != null) {
                try {
                    _con.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
        return _list;
    } //end method readColumnData