.net 从url读取内容到内存MemoryStream流中

直接使用 response.GetResponseStream()返回的流会因为网络延时问题.导致有些代码提示.
stream Is corrupted 流已损坏.
需要先下载到内存中.转换哼内存流以后在给其它代码使用.

        /// <summary>
        /// 从url读取内容到内存MemoryStream流中
        /// </summary>
        /// <param name="url"></param>
        /// <returns></returns>
        private static MemoryStream DownLoadFielToMemoryStream(string url)
        {
            var wreq = HttpWebRequest.Create(url) as HttpWebRequest;
            HttpWebResponse response = wreq.GetResponse() as HttpWebResponse;
            MemoryStream ms = null;
            using (var stream = response.GetResponseStream())
            {
                Byte[] buffer = new Byte[response.ContentLength];
                int offset = 0, actuallyRead = 0;
                do
                {
                    actuallyRead = stream.Read(buffer, offset, buffer.Length - offset);
                    offset += actuallyRead;
                }
                while (actuallyRead > 0);
                ms = new MemoryStream(buffer);
            }
            response.Close();
            return ms;
        }