阅读器关闭时尝试调用 Read 无效

public static SqlDataReader GetDataReader(string sql, params SqlParameter[] parameters)
    {
        SqlConnection conn = new SqlConnection(connstr);
        SqlCommand cmd = new SqlCommand(sql, conn);
        foreach (SqlParameter parameter in parameters)
        {
            cmd.Parameters.Add(parameter);
        }

        try
        {
            conn.Open();
            return   cmd.ExecuteReader(CommandBehavior.CloseConnection);//关闭SqlDataReader 会自动关闭Sqlconnection

        }
        catch (Exception e)
        {
            throw new Exception("执行任务失败:" + e.Message + "   " + sql);
        }

    }