Download Stream file from URL - asp net

Question

I need to stream a file which will result in save as prompt in the browser  The issue is  the directory that the file is located is virtually mapped  so I am unable to use Server MapPath to determine it s actual location  The directory is not in the same location  or even phyical server on the live boxes  as the website   I d like something like the following  but that will allow me to pass a web URL  and not a server file path   I may have to end up building my file path from a config base path  and then append on the rest of the path  but hopefully I can do it this way instead   var filePath   Server MapPath DOCUMENT PATH    if   File Exists filePath       return   var fileInfo   new System IO FileInfo filePath   Response ContentType    application octet-stream   Response AddHeader  Content-Disposition   String Format  attachment filename    0      filePath    Response AddHeader  Content-Length   fileInfo Length ToString     Response WriteFile filePath   Response End

User · Answer

You could try using the DirectoryEntry class with the IIS path prefix   using DirectoryEntry de   new DirectoryEntry  IIS   Localhost w3svc 1 root    DOCUMENT PATH         filePath   de Properties  Path   Value     if   File Exists filePath           return   var fileInfo   new System IO FileInfo filePath   Response ContentType    application octet-stream   Response AddHeader  Content-Disposition   String Format  attachment filename    0      filePath    Response AddHeader  Content-Length   fileInfo Length ToString     Response WriteFile filePath   Response End

User · Answer

You could use HttpWebRequest to get the file and stream it back to the client  This allows you to get the file with a url  An example of this that I found   but can t remember where to give credit   is        Create a stream for the file     Stream stream   null         This controls how many bytes to read at a time and send to the client     int bytesToRead   10000          Buffer to read bytes in chunk size specified above     byte   buffer   new Byte bytesToRead           The number of bytes read     try               Create a WebRequest to get the file       HttpWebRequest fileReq    HttpWebRequest  HttpWebRequest Create url            Create a response for this request       HttpWebResponse fileResp    HttpWebResponse  fileReq GetResponse           if  fileReq ContentLength  gt  0          fileResp ContentLength   fileReq ContentLength             Get the Stream returned from the response         stream   fileResp GetResponseStream                prepare the response to the client  resp is the client Response         var resp   HttpContext Current Response             Indicate the type of data being sent         resp ContentType    application octet-stream              Name the file          resp AddHeader  Content-Disposition    attachment  filename       fileName                  resp AddHeader  Content-Length   fileResp ContentLength ToString              int length          do                          Verify that the client is connected              if  resp IsClientConnected                                   Read data into the buffer                  length   stream Read buffer  0  bytesToRead                       and write it out to the response s output stream                 resp OutputStream Write buffer  0  length                       Flush the data                 resp Flush                       Clear the buffer                 buffer   new Byte bytesToRead                             else                                  cancel the download if client has disconnected                 length   -1                          while  length  gt  0     Repeat until no data is read           finally               if  stream    null                          Close the input stream             stream Close

User · Answer

If you are looking for a  NET Core version of  Dallas s answer  use the below           Stream stream   null             This controls how many bytes to read at a time and send to the client         int bytesToRead   10000              Buffer to read bytes in chunk size specified above         byte   buffer   new Byte bytesToRead               The number of bytes read         try                         Create a WebRequest to get the file             HttpWebRequest fileReq    HttpWebRequest HttpWebRequest Create   file url                   Create a response for this request             HttpWebResponse fileResp    HttpWebResponse fileReq GetResponse                 if  fileReq ContentLength  gt  0                  fileResp ContentLength   fileReq ContentLength                 Get the Stream returned from the response             stream   fileResp GetResponseStream                    prepare the response to the client  resp is the client Response             var resp   HttpContext Response                 Indicate the type of data being sent             resp ContentType    application octet-stream                  Name the file              resp Headers Add  Content-Disposition    attachment  filename test zip                resp Headers Add  Content-Length   fileResp ContentLength ToString                  int length              do                                  Verify that the client is connected                  if   HttpContext RequestAborted IsCancellationRequested                                           Read data into the buffer                      length   stream Read buffer  0  bytesToRead                           and write it out to the response s output stream                     resp Body Write buffer  0  length                           Clear the buffer                     buffer   new Byte bytesToRead                                     else                                          cancel the download if client has disconnected                     length   -1                                  while  length  gt  0     Repeat until no data is read                   finally                       if  stream    null                                  Close the input stream                 stream Close

User · Answer

2 years later  I used Dallas  answer  but I had to change the HttpWebRequest to FileWebRequest since I was linking to direct files  Not sure if this is the case everywhere  but I figured I d add it  Also  I removed  var resp   Http Current Resonse    and just used Http Current Response in place wherever resp was referenced

User · Answer

I do this quite a bit and thought I could add a simpler answer  I set it up as a simple class here  but I run this every evening to collect financial data on companies I m following   class WebPage       public static string Get string uri                string results    N A            try                       HttpWebRequest req    HttpWebRequest WebRequest Create uri               HttpWebResponse resp    HttpWebResponse req GetResponse                 StreamReader sr   new StreamReader resp GetResponseStream                 results   sr ReadToEnd                sr Close                      catch  Exception ex                        results   ex Message                    return results            In this case I pass in a url and it returns the page as HTML  If you want to do something different with the stream instead you can easily change this   You use it like this   string page   WebPage Get  http   finance yahoo com q s yhoo

User · Answer

The accepted solution from Dallas was working for us if we use Load Balancer on the Citrix Netscaler  without WAF policy     The download of the file doesn t work through the LB of the Netscaler when it is associated with WAF as the current scenario  Content-length not being correct  is a RFC violation and AppFW resets the connection  which doesn t happen when WAF policy is not associated   So what was missing was   Response End     See also  Trying to stream a PDF file with asp net is producing a  quot damaged file quot

User · Answer

Download url to bytes and convert bytes into stream   using  var client   new WebClient          var content   client DownloadData url       using  var stream   new MemoryStream content

[c#] Download/Stream file from URL - asp.net

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