PDF链接转字节流输出

当一个PDF链接是重要的、不随便公开的、权限控制的，就可以用包一层方法，把PDF转另已页面输出

   // PDF链接
   string _electronicUrl ="https://wwwimages2.adobe.com/www.adobe.com/content/dam/acom/cn/legal/licenses-terms/pdf/PlatformClients_PC_WWEULA-zh_CN-20150407_1357.pdf";

   var request = (HttpWebRequest) WebRequest.Create(_electronicUrl);
   request.Timeout = 30000;
   WebResponse response = request.GetResponse();
   //string type = response.ContentType;
   Stream stream = response.GetResponseStream();

   MemoryStream ms = new MemoryStream();
   const int bufferLen = 5120;
   byte[] buffer_m = new byte[bufferLen];
   int count = 0;
   while ((count = stream.Read(buffer_m, 0, bufferLen)) > 0)
   {
       ms.Write(buffer_m, 0, count);
   }
   stream.Close();
   int buffsize = (int) ms.Length; //rs.Length 此流不支持查找,先转为MemoryStream
   byte[] buffer = new byte[buffsize];
   ms.Position = 0;
   ms.Read(buffer, 0, buffsize);
   ms.Close();
   string strBase64 = Convert.ToBase64String(buffer);