private  Stream GetStream(string strLink)
    {
        HttpWebRequest request = null;
        try
        {
            request = (HttpWebRequest)WebRequest.Create(strLink);
            request.UserAgent = "Mozilla/5.0 (compatible; MSIE 7.0; Windows NT 5.1; SV1;.NET CLR 2.0.50727)";
            return request.GetResponse().GetResponseStream();
        }
        catch
        {
            request.Abort();
            return null;
        }
    }

    public bool SaveImage(string strLink,string strFolder,string strNewName,bool unique)
    {
        try
        {
            string strTmp = string.Empty;
            readstream = GetStream(strLink);
            if (readstream == null)
            {
                throw new Exception("获取图片错误");
            }
      
            if (unique)
            {
                filestream = new FileStream(GetPath(strLink,strFolder,strNewName), FileMode.CreateNew, FileAccess.Write);
            }
            else
            {
                filestream = new FileStream(GetPath(strLink, strFolder, strNewName), FileMode.Create, FileAccess.Write);
            }
            do
            {
                length = readstream.Read(buffer, 0, buffer.Length);
                if (length == 0)
                {
                    break;
                }
                filestream.Write(buffer, 0, length);
            }
            while (length > 0);
            return true;
        }
        catch
        {
            return false;
        }
        finally
        {
            Close();
        }
    }

//流都是stream类型

我写ftp的时候用到的，，，具体的你自己改！
close这个函数的命令就是关闭这些流！！