I am using the code below which I have found on one of the forums to download a file in remote server. it seems it is working. However, the downloaded file is corrupted and I cannot unzip.
Do you have any idea why it is so? or if my approach is wrong, could you suggest me a better way please?
protected void Page_Load(object sender, EventArgs e)
{
string url = "http://server/scripts/isynch.dll?panel=AttachmentDownload&NoteSystem=SyncNotes&NoteType=Ticket&NoteId=1&Field=supp&File=DisplayList%2etxt";
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
req.Credentials = new NetworkCredential("user", "pass");
HttpWebResponse resp = (HttpWebResponse)req.GetResponse();
////Initialize the output stream
Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AppendHeader("Content-Disposition:", "attachment; filename=" + "DisplayList.txt");
Response.AppendHeader("Content-Length", resp.ContentLength.ToString());
////Populate the output stream
byte[] ByteBuffer = new byte[resp.ContentLength];
Stream rs = req.GetResponse().GetResponseStream();
rs.Read(ByteBuffer, 0, ByteBuffer.Length);
Response.BinaryWrite(ByteBuffer);
Response.Flush();
///Cleanup
Response.End();
rs.Dispose();
}
First of all, use application/octet-stream as it is the standard content type for downloads.
new byte[resp.ContentLength + 1] will define a buffer which is one byte larger than content type. I believe this is the reason for corruption. Use new byte[resp.ContentLength].
I actually recommend re-writing it and removing memorystream:
const int BufferLength = 4096;
byte[] byteBuffer = new byte[BufferLength];
Stream rs = req.GetResponse().GetResponseStream();
int len = 0;
while ( (len = rs.Read(byteBuffer,0,byteBuffer.Length))>0)
{
if (len < BufferLength)
{
Response.BinaryWrite(byteBuffer.Take(len).ToArray());
}
else
{
Response.BinaryWrite(byteBuffer);
}
Response.Flush();
}
the article on http://support.microsoft.com/default.aspx?scid=kb;en-us;812406 solved my problem. Many thanks to #Aliostad for his effort to help me.
Related
I am working with a MS Dynamics Nav Database that have a file attachment tables. The files are stored in MS SQL. I am able to pull the files to my desktop with a custom asp.net application that I have built, but when I open the files, they are corrupted. These are PDFs files that are located in the "image" file type column of the database and I have tried to download over 20 files. All of them varies in size and seem to download successfully.
The reason why I suspect these are PDFs files is because the column right next to the binary columns give me the name of the file as in PDF format. I have also tried to renaming the file after I download to different image formats but without any luck when I tried to open it. This is not my first project to retrieve binary files, from MS SQL database. If anyone work on getting files off the Nav database before, please help me. The sample code below I wrote to retrieve files using LINQ to SQL when I give it a specific ID in the browser. Please advice me if you know any sort of compression or encryption in the binary files itself and how to grab the file successfully to read it. Thanks
protected void getFileFromID(string queryid)
{
string Filename = string.Empty;
byte[] bytes;
try
{
DataClassesFilesDataContext dcontext = new DataClassesFilesDataContext();
var myfile = (from file in dcontext.Comptroller_File_Attachments
where file.No_ == queryid
select file).First();
if (myfile.Table_ID.ToString().Length > 0 && myfile.Attachment != null)
{
Filename = myfile.FileName.ToString();
bytes = myfile.Attachment.ToArray();
Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment; filename=" + Filename);
Response.BinaryWrite(bytes);
Response.End();
}
else
{
Response.Write("no file exist");
}
}
catch (Exception e)
{
Response.Write(e);
}
}
Well. I figured it out. I read on a blog that 4 bytes was the "magic number" to get rid off. So all you have to do is get rid of 4 bytes from the BLOB bytes array and then decompress it with DeflateStream. The example code I post below is an example where it takes in a byte array and skip the first 4 using LINQ-to-SQL and return the byte and string filename for the 2nd function. It also pass in a queryid string parameter. I am sure the code can be improve more for efficiency purposes. For those who have trouble with this, just give this a try.
//get bytes and remove first 4 bytes from bytes array
protected Tuple<byte[], string> getBytesfromFile(string queryID)
{
byte[] MyFilebytes = null;
string filename = string.Empty;
try
{
DataClassesFilesDataContext dcontext = new DataClassesFilesDataContext();
var myfile = (from file in dcontext.Comptroller_File_Attachments
where file.No_ == queryID
select file).First();
if (myfile.Table_ID.ToString().Length > 0 && myfile.Attachment != null)
{
MyFilebytes = myfile.Attachment.ToArray().Skip(4).ToArray();
filename = myfile.FileName.ToString();
}
else
Response.Write("no byte to return");
}
catch
{
Response.Write("no byte");
}
return Tuple.Create(MyFilebytes, filename);
}
//after getting the remaining bytes (after removing 4 first byte) deflate the byte and then store it in a memory steam and get the result back.
protected void getFile()
{
try
{
string Filename = string.Empty;
byte[] myfile = getBytesfromFile(getQueryID()).Item1;
byte[] result;
using (Stream input = new DeflateStream(new MemoryStream(myfile),
CompressionMode.Decompress))
{
using (MemoryStream output = new MemoryStream())
{
input.CopyTo(output);
result = output.ToArray();
}
}
Filename = getBytesfromFile(getQueryID()).Item2;
Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment; filename=" + Filename);
Response.BinaryWrite(result);
Response.End();
}
catch (Exception e)
{
Response.Write(e);
}
}
//pass in file id
protected string getQueryID()
{
QueryID.QueryStringID = Request.QueryString["fileid"];
return QueryID.QueryStringID;
}
i have application like email messaging system. here i adjust one solution to download all file that are in table from particular post.
this is my code:
protected void lbu_download_all_Click(object sender, EventArgs e)
{
if (rpt_file_list.Items.Count > 0)
{
using (DataClassesDataContext db = new DataClassesDataContext())
{
var query = from f in db.Files
where f.Post_History_id == int.Parse(post_id.Value.ToString())
select new
{
FileName = f.File_name,
File_ext= f.File_ext
};
foreach (var item in query)
{
System.IO.FileInfo objFile = new FileInfo(Server.MapPath("~/PostFiles/" + item.FileName.ToString() + item.File_ext.ToString()));
if (objFile.Exists)
{
Response.Clear();
string strFileName = item.FileName.ToString() + item.File_ext.ToString();
Response.AddHeader("Content-Disposition", "attachment; filename=" + strFileName);
Response.AddHeader("Content-Length", objFile.Length.ToString());
Response.ContentType = "application/octet-stream";
Response.WriteFile(objFile.FullName);
Response.BufferOutput = true;
Response.Flush();
}
}
}
}
else
{
StringBuilder sb = new StringBuilder();
sb.Append("<script type = 'text/javascript'>");
sb.Append(" No files found to download');");
sb.Append("</script>");
ClientScript.RegisterStartupScript(this.GetType(), "script", sb.ToString());
}
}
i don't know what is problm please help me..
You won't be able to download multiple files like that, I imagine what is happening is that the loop goes through once and on the second iteration it then throws the exception.
What you really should be doing is zipping all the files into one file to download, this question should give you an idea of what I mean.
By zipping the file you'll also get the benefit of compression (less bandwidth, faster transfer) and the user (in your current scenario) won't be presented with multiple 'Save As' dialog windows (much more professional!).
This link may also help you with some other potential ideas (like having a 'Download' page with URL parameters to identify the file). I'm more a fan of a zipped single file option though!
Do you have Response.BufferOutput = true; set properly? If not, the page will be sent as it is generated, which means the Response.Clear() won't do what you want :)
I have the following code...
public partial class DownloadFile : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string FilePath = "[FTPPath]";
Download downloadFile = new Download();
Server.ScriptTimeout = 54000;
try
{
long size = downloadFile.GetFileSize(FilePath);
using (FtpWebResponse ftpResponse = downloadFile.BrowserDownload(FilePath))
using (Stream streamResponse = ftpResponse.GetResponseStream())
{
string fileName = FilePath.Substring(FilePath.LastIndexOf("/") + 1);
int bufferSize = 65536;
byte[] buffer = new byte[bufferSize];
int readCount;
readCount = streamResponse.Read(buffer, 0, bufferSize);
// Read file into buffer
//streamResponse.Read(buffer, 0, (int)size);
Response.Clear();
Response.Buffer = false;
Response.BufferOutput = false;
//Apparently this line helps with old version of IE that like to cache stuff no matter how much you tell them!
Response.AddHeader("Pragma", "public");
//Expires: 0 forces the browser to always thing the page is "stale" therefore forcing it to never cache the page and therefore always re-downloads the page when viewed. Therefore no nasty experiences if we change the authentication details.
Response.Expires = 0;
//Again this line forces the browser not to cache the page.
Response.AddHeader("Cache-Control", "no-cache, must-revalidate");
Response.AddHeader("Cache-Control", "public");
Response.AddHeader("Content-Description", "File Transfer");
Response.ContentType = "application/zip";
Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
Response.AddHeader("Content-Transfer-Encoding", "binary");
Response.AddHeader("Content-Length", size.ToString());
// writes buffer to OutputStream
while (readCount > 0)
{
Response.OutputStream.Write(buffer, 0, bufferSize);
readCount = streamResponse.Read(buffer, 0, bufferSize);
Response.Flush();
}
Response.End();
Server.ScriptTimeout = 90;
}
}
catch (Exception ex)
{
Response.Write("<p>" + ex.Message + "</p>");
Server.ScriptTimeout = 90;
}
}
}
To download .zip files from an FTP (please ignore the header rubbish about preventing caching unless this is related to the issue).
So downloadFile is a class I have written using FTPWebRequest/Response with SSL enabled that can do to two things; one is return the file size (GetFileSize) of a file on our FTP and the other is to set FtpWebRequest.Method = WebRequestMethods.Ftp.DownloadFile to allow the download of a file.
Now the code appears to work perfectly, you get a nice zip downloaded of exactly the same size as the one on the FTP however, this is where the quirks begin.
The zip files are always corrupted, no matter how small. In theory, very small files should be okay, but you'll see why in a moment. Because of this, I decided to compare the files in binary.
If I set bufferSize to anything other than the size of the file
(i.e. 1024, 2048, 65536), the first 16k (16384 bytes) downloads
perfectly, and then the stream just writes zeros to the end of the
file.
If I set bufferSize = size (filesize), the stream appears to download the full file, until you look more closely. The file is an exact replica up to the first 64k, and then an extra character appears in the downloaded file (this chararacter never seems to be the same).
After this extra byte, the files are exactly the same again. An extra byte appears to get added every 64k, meaning that by the end of 65MB file, the two files are massively out of sync. Because the download length is limited to the size of the file on the server, the end of the file gets truncated in the downloaded file. The archive will allow access to it as all the CRC checks fail.
Any help would be much appreciated. Cheers.
Now changed my code somewhat to use WebRequest and WebResponse to grabe a zip using Http from the web server itself. Here is the code...
public partial class DownloadFile : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string FilePath = [http path];
Server.ScriptTimeout = 54000;
try
{
WebRequest HWR = WebRequest.Create(FilePath);
HWR.Method = WebRequestMethods.File.DownloadFile;
using (WebResponse FWR = HWR.GetResponse())
using (BinaryReader streamResponse = new BinaryReader(FWR.GetResponseStream()))
{
string fileName = FilePath.Substring(FilePath.LastIndexOf("/") + 1);
int bufferSize = 2048;
byte[] buffer = new byte[bufferSize];
int readCount;
readCount = streamResponse.Read(buffer, 0, bufferSize);
Response.Clear();
Response.Buffer = false;
Response.BufferOutput = false;
//Apparently this line helps with old version of IE that like to cache stuff no matter how much you tell them!
Response.AddHeader("Pragma", "public");
//Expires: 0 forces the browser to always thing the page is "stale" therefore forcing it to never cache the page and therefore always re-downloads the page when viewed. Therefore no nasty experiences if we change the authentication details.
Response.Expires = 0;
//Again this line forces the browser not to cache the page.
Response.AddHeader("Cache-Control", "no-cache, must-revalidate");
Response.AddHeader("Cache-Control", "public");
Response.AddHeader("Content-Description", "File Transfer");
Response.ContentType = "application/zip";
Response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
Response.AddHeader("Content-Transfer-Encoding", "binary");
// writes buffer to OutputStream
while (readCount > 0)
{
Response.OutputStream.Write(buffer, 0, bufferSize);
Response.Flush();
readCount = streamResponse.Read(buffer, 0, bufferSize);
}
//Response.Write(testString);
Response.End();
Server.ScriptTimeout = 90;
}
}
catch (Exception ex)
{
Response.Write("<p>" + ex.Message + "</p>");
Server.ScriptTimeout = 90;
}
}
}
This code is more simple but it is still corrupting the data. I'm sure there's something very simple I'm doing wrong, but I just can't spot it or find a test to show me where I am going wrong. Please help :)
On your line
Response.OutputStream.Write(buffer, 0, bufferSize);
change bufferSize to readCount so that you only write the number that you actually read.
In my ASP.NET application,When I try to open PDF file by using the below code, I am getting an error
CODE USED TO SHOW PDF FILE
FileStream MyFileStream = new FileStream(filePath, FileMode.Open);
long FileSize = MyFileStream.Length;
byte[] Buffer = new byte[(int)FileSize + 1];
MyFileStream.Read(Buffer, 0, (int)MyFileStream.Length);
MyFileStream.Close();
Response.ContentType = "application/pdf";
Response.AddHeader("content-disposition", "attachment; filename="+filePath);
Response.BinaryWrite(Buffer);
ERROR I AMN GETTING
"There was an error opening this document.The file is damaged and could not open"
Sounds like your using an aspx file to output the pdf. Have you considered using an ashx file which is an HttpHandler? It bypasses all the typical aspx overhead stuff and is more efficient for just serving up raw data.
Here is an example of the ashx using your code:
<% WebHandler Language="c#" class="ViewPDF" %>
public class ViewPDF : IHttpHandler
{
public void ProcessRequest(HttpContext context)
{
FileStream MyFileStream = new FileStream(filePath, FileMode.Open);
long FileSize = MyFileStream.Length;
byte[] Buffer = new byte[(int)FileSize + 1];
MyFileStream.Read(Buffer, 0, (int)MyFileStream.Length);
MyFileStream.Close();
Response.ContentType = "application/pdf";
Response.AddHeader("content-disposition", "attachment; filename="+filePath);
Response.BinaryWrite(Buffer);
}
public bool IsReusable
{
get { return false; }
}
}
If you still want to use the aspx page. Make sure you are doing the following:
// At the beginning before you do any response stuff do:
Response.Clear();
// When you are done all your response stuff do:
Response.End();
That should solve your problem.
You must flush the response otherwise it gets partially transmitted.
Response.Flush();
In addition to ocedcio's reply, you need to be aware that Stream.Read() does not necessarily read all of the bytes requested. You should examine the return value from Stream.Read() and continue reading if less bytes are read than requested.
See this question & answer for the details: Creating a byte array from a stream
I'm making a simple download service so a user can download all his images from out site.
To do that i just zip everything to the http stream.
However it seems everything is stored in memory, and the data isn't sent til zip file is complete and the output closed.
I want the service to start sending at once, and not use too much memory.
public void ProcessRequest(HttpContext context)
{
List<string> fileNames = GetFileNames();
context.Response.ContentType = "application/x-zip-compressed";
context.Response.AppendHeader("content-disposition", "attachment; filename=files.zip");
context.Response.ContentEncoding = Encoding.Default;
context.Response.Charset = "";
byte[] buffer = new byte[1024 * 8];
using (ICSharpCode.SharpZipLib.Zip.ZipOutputStream zipOutput = new ICSharpCode.SharpZipLib.Zip.ZipOutputStream(context.Response.OutputStream))
{
foreach (string fileName in fileNames)
{
ICSharpCode.SharpZipLib.Zip.ZipEntry zipEntry = new ICSharpCode.SharpZipLib.Zip.ZipEntry(fileName);
zipOutput.PutNextEntry(zipEntry);
using (var fread = System.IO.File.OpenRead(fileName))
{
ICSharpCode.SharpZipLib.Core.StreamUtils.Copy(fread, zipOutput, buffer);
}
}
zipOutput.Finish();
}
context.Response.Flush();
context.Response.End();
}
I can see the the worker process memory growing while it makes the file, and then releases the memory when its done sending. How do i do this without using too much memory?
Disable response buffering with context.Response.BufferOutput = false; and remove the Flush call from the end of your code.
use Response.BufferOutput = false; at start of ProcessRequest and flush response after each file.
FYI. This is working code to recursively add an entire tree of files, with streaming to browser:
string path = #"c:\files";
Response.Clear();
Response.ContentType = "application/zip";
Response.AddHeader("Content-Disposition", string.Format("attachment; filename=\"{0}\"", "hive.zip"));
Response.BufferOutput = false;
byte[] buffer = new byte[1024 * 1024];
using (ZipOutputStream zo = new ZipOutputStream(Response.OutputStream, 1024 * 1024)) {
zo.SetLevel(0);
DirectoryInfo di = new DirectoryInfo(path);
foreach (string file in Directory.GetFiles(di.FullName, "*.*", SearchOption.AllDirectories)) {
string folder = Path.GetDirectoryName(file);
if (folder.Length > di.FullName.Length) {
folder = folder.Substring(di.FullName.Length).Trim('\\') + #"\";
} else {
folder = string.Empty;
}
zo.PutNextEntry(new ZipEntry(folder + Path.GetFileName(file)));
using (FileStream fs = File.OpenRead(file)) {
ICSharpCode.SharpZipLib.Core.StreamUtils.Copy(fs, zo, buffer);
}
zo.Flush();
Response.Flush();
}
zo.Finish();
}
Response.Flush();