I have a PDF which is hosted in say http://test.com/mypdf.pdf.
How can I convert the PDF to Stream and then using this Stream convert it back to PDF.
I tried the following but got an exception(see image):
private static Stream ConvertToStream(string fileUrl)
{
HttpWebResponse aResponse = null;
try
{
HttpWebRequest aRequest = (HttpWebRequest)WebRequest.Create(fileUrl);
aResponse = (HttpWebResponse)aRequest.GetResponse();
}
catch (Exception ex)
{
}
return aResponse.GetResponseStream();
}
This will work:
private static Stream ConvertToStream(string fileUrl)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(fileUrl);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
try {
MemoryStream mem = new MemoryStream();
Stream stream = response.GetResponseStream();
stream.CopyTo(mem,4096);
return mem;
} finally {
response.Close();
}
}
However you are entirely responsible for the lifetime of the returned memory stream.
A better approach is:
private static void ConvertToStream(string fileUrl, Stream stream)
{
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(fileUrl);
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
try {
Stream response_stream = response.GetResponseStream();
response_stream.CopyTo(stream,4096);
} finally {
response.Close();
}
}
You can then do something like:
using (MemoryStream mem = new MemoryStream()) {
ConvertToStream('http://www.example.com/',mem);
mem.Seek(0,SeekOrigin.Begin);
... Do something else ...
}
You may also be able to return the response stream directly but you'd have to check on the lifetime of that, releasing the response may release the stream, hence the mem copy.
You may want to take a look at WebClient.DownloadFile.
You give it a URL and local file name and it saves the file straight to disk. Might save you a step or two.
You could also try WebClient.DownloadData which saves the file to an in-memory byte[].
EDIT
You did not specify the protocol of the web-service you are posting the file to. The simplest form (RESTful) would be just to POST the file to data to another URL. Here is how you would do that.
using (WebClient wc = new WebClient())
{
// copy data to byte[]
byte[] data = wc.DownloadData("http://somesite.com/your.pdf");
// POST data to another URL
wc.Headers.Add("Content-Type","application/pdf");
wc.UploadData("http://anothersite.com/your.pdf", data);
}
If you are using SOAP, you would have to convert the file to a Base64 string, but hopefully you are using a generated client which takes care of that for you. If you could elaborate on the type of web-service you are sending the file to, I could probably provide some more information..
Related
I am trying to make a httplistener server in c# that sends files to the client (who is on a browser). This is my code:
static void SendFile(HttpListenerResponse response, string FileName, string ContentType) {
response.ContentType = ContentType;
// Read contents of file
var reader = new StreamReader(FileName);
var contents = reader.ReadToEnd();
reader.Close();
// Write to output stream
var writer = new StreamWriter(output);
writer.Write(contents);
// Wrap up.
writer.Close();
stream.Close();
response.Close();
}
Unfortunately, this code cannot send binary files, such as images, PDFs, and lots of other file types. How can I make this SendFile function binary-safe?
Thank you for all the comments and the gist link! The solution where you read from the file as a byte[] and write those bytes to the output stream I looked up worked, but is was kind of confusing, so I made a really short SendFile function.
static void SendFile(HttpListenerResponse response, string FileName, string ContentType) {
response.AddHeader("Content-Type", ContentType);
var output = response.OutputStream;
// Open the file
var file = new FileStream(FileName, FileMode.Open, FileAccess.Read);
// Write to output stream
file.CopyTo(output);
// Wrap up.
file.Close();
stream.Close();
response.Close();
}
This code just copies the file to the output stream.
I have code below that read ftp response stream and write data to two different files (test1.html & test2.html). The 2nd StreamReader throw a stream was not readable error. The response stream should be readable because it's not out of scope yet and the dispose shouldn't be called. Can someone explain why?
static void Main(string[] args)
{
// Make sure it is ftp
if (Properties.Settings.Default.FtpEndpoint.Split(':')[0] != Uri.UriSchemeFtp) return;
// Intitalize object to used to communicuate to the ftp server
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(Properties.Settings.Default.FtpEndpoint + "/test.html");
// Credentials
request.Credentials = new NetworkCredential(Properties.Settings.Default.FtpUser, Properties.Settings.Default.FtpPassword);
// Set command method to download
request.Method = WebRequestMethods.Ftp.DownloadFile;
// Get response
FtpWebResponse response = (FtpWebResponse)request.GetResponse();
using (Stream output = File.OpenWrite(#"C:\Sandbox\vs_projects\FTP\FTP_Download\test1.html"))
using (Stream responseStream = response.GetResponseStream())
{
responseStream.CopyTo(output);
Console.WriteLine("Successfully wrote stream to test.html");
try
{
using (StreamReader reader = new StreamReader(responseStream))
{
string file = reader.ReadToEnd();
File.WriteAllText(#"C:\Sandbox\vs_projects\FTP\FTP_Download\test2.html", file);
Console.WriteLine("Successfully wrote stream to test2.html");
}
}
catch (Exception ex)
{
Console.WriteLine($"Exception: {ex}");
}
}
}
You can't read from the stream twice. After this call:
responseStream.CopyTo(output);
... you've already read all the data in the stream. There's nothing left to read, and you can't "rewind" the stream (e.g. seeking to the beginning) because it's a network stream. Admittedly I'd expect it to just be empty rather than throwing an error, but the details don't really matter much as it's not a useful thing to try to do.
If you want to make two copies of the same data, the best option is to copy it to disk as you're already doing, then read the file that you've just written.
(Alternatively, you could just read it into memory by copying to a MemoryStream, then you can rewind that stream and read from it repeatedly. But if you're already going to save it to disk, you might as well do that first.)
i was following this example, but when download starts it hangs and than after a minute it shows server error. I guess response end before all data id sent to client.
Do you know another way that i can do this or why it's not working?
Writing to Output Stream from Action
private void StreamExport(Stream stream, System.Collections.Generic.IList<byte[]> data)
{
using (BufferedStream bs = new BufferedStream(stream, 256 * 1024))
using (StreamWriter sw = new StreamWriter(bs))
{
foreach (var stuff in data)
{
sw.Write(stuff);
sw.Flush();
}
}
}
Can you show the calling method? What is the Stream being passed in? Is it the Response Stream?
There are many helpful classes to use that you don't have to chuck yourself because they chunk by default. If you use StreamContent there is a constructor overload where you can specify buffer size. I believe default is 10kB.
From memory here so it my not be complete:
[Route("download")]
[HttpGet]
public async Task<HttpResponseMessage> GetFile()
{
var response = this.Request.CreateResponse(HttpStatusCode.OK);
//don't use a using statement around the stream because the framework will dispose StreamContent automatically
var stream = await SomeMethodToGetFileStreamAsync();
//buffer size of 4kB
var content = new StreamContent(stream, 4096);
response.Content = content;
return response;
}
I'm trying to convert a .db file to binary so I can stream it across a web server. I'm pretty new to C#. I've gotten as far as looking at code snippets online but I'm not really sure if the code below puts me on the right track. How I can write the data once I read it? Does BinaryReader automatically open up and read the entire file so I can then just write it out in binary format?
class Program
{
static void Main(string[] args)
{
using (FileStream fs = new FileStream("output.bin", FileMode.Create))
{
using (BinaryWriter bw = new BinaryWriter(fs))
{
long totalBytes = new System.IO.FileInfo("input.db").Length;
byte[] buffer = null;
BinaryReader binReader = new BinaryReader(File.Open("input.db", FileMode.Open));
}
}
}
}
Edit: Code to stream the database:
[WebGet(UriTemplate = "GetDatabase/{databaseName}")]
public Stream GetDatabase(string databaseName)
{
string fileName = "\\\\computer\\" + databaseName + ".db";
if (File.Exists(fileName))
{
FileStream stream = File.OpenRead(fileName);
if (WebOperationContext.Current != null)
{
WebOperationContext.Current.OutgoingResponse.ContentType = "binary/.bin";
}
return stream;
}
return null;
}
When I call my server, I get nothing back. When I use this same type of method for a content-type of image/.png, it works fine.
All the code you posted will actually do is copy the file input.db to the file output.bin. You could accomplish the same using File.Copy.
BinaryReader will just read in all of the bytes of the file. It is a suitable start to streaming the bytes to an output stream that expects binary data.
Once you have the bytes corresponding to your file, you can write them to the web server's response like this:
using (BinaryReader binReader = new BinaryReader(File.Open("input.db",
FileMode.Open)))
{
byte[] bytes = binReader.ReadBytes(int.MaxValue); // See note below
Response.BinaryWrite(bytes);
Response.Flush();
Response.Close();
Response.End();
}
Note: The code binReader.ReadBytes(int.MaxValue) is for demonstrating the concept only. Don't use it in production code as loading a large file can quickly lead to an OutOfMemoryException. Instead, you should read in the file in chunks, writing to the response stream in chunks.
See this answer for guidance on how to do that
https://stackoverflow.com/a/8613300/141172
I have used Google static map and created linked resource and embedded it in email and sending the mail to all users. I send a request to Google server and convert the response as stream and then created linked resource using that stream.
The problem is I have used for loop and sent mail to all email id's present in the Database table, I have created linked resource being created inside the for loop so each time the same image is requested from the Google server and mailed to user's. I want to prevent this, only for the first time the request has to be sent to Google and i have to store that response stream and use it to create linked resource.
How to do this? I have tried storing the stream in local stream variable and created linked resource using that stream variable, I have also stored the stream in viewstate as well as in session but none of the methods worked out!
for (iCnt = 0; iCnt < dsEmailIds.Tables[0].Rows.Count; iCnt++)
{
//Linked resource to embed Google map in mail
LinkedResource lnkResMain;
if (imgPhotos.Src.Contains("maps.google.com"))
lnkResMain = new LinkedResource(getStream(imgPhotos.Src));
//send mail
mail.SendMail(fromAddress,dsEmailIds.Tables[0].Rows[0]["toAddress"].ToString(),lnkResMain);
}
//this converts string image url to stream since stream can be used to create linked resource
public Stream getStream(string imgUrl)
{
System.Net.WebRequest req = System.Net.WebRequest.Create(imgUrl);
System.Net.WebResponse response = req.GetResponse();
Stream stream = response.GetResponseStream();
return stream;
}
Using single stream in multiple emails will not work because for first email, the stream will read (and closed) and so will not be available for subsequent emails.
Why not save the map response stream into a temporary file and then create a linked resource using the file name (use this or this constructors - I will prefer later to specify the content type as well as).
The code for this functionality is:
//Sends request to Google and gets the response as stream
//imgUrl - image url for the Google static map
public Stream getStream(string imgUrl)
{
Stream stream = null;
try
{
System.Net.WebRequest req = System.Net.WebRequest.Create(imgUrl);
System.Net.WebResponse response = req.GetResponse();
stream = response.GetResponseStream();
return stream;
}
catch (Exception ex)
{
throw ex;
}
}
//Converts stream to image and stores the image in temp files location
//strm - Stream containing Google map
//imageName - image Name to be saved in temp file
public void SaveStreamAsImage(Stream strm,string imageName)
{
System.Drawing.Image img = null;
try
{
img = System.Drawing.Image.FromStream(strm);
img.Save(System.IO.Path.GetTempPath() + imageName, System.Drawing.Imaging.ImageFormat.Jpeg);
}
catch (Exception ex)
{
throw ex;
}
finally
{
strm.Dispose();
strm.Close();
img.Dispose();
}
}
//Deletes the temp image file after mailing to all users
//filePath - file path of image which is to be deleted
public void DeleteFile(string filePath)
{
if (File.Exists(filePath))
{
File.Delete(filePath);
}
}
public void SendEmail()
{
for (iCnt = 0; iCnt < dsEmailIds.Tables[0].Rows.Count; iCnt++)
{
//Linked resource to embed Google map in mail LinkedResource lnkResMain;
if (imgPhotos.Src.Contains("maps.google.com"))
{
Stream strm = getStream(imgPhotos.Src);
SaveStreamAsImage(strm, "img1");
}
//send mail
mail.SendMail(fromAddress,dsEmailIds.Tables[0].Rows[0]["toAddress"].ToString(),lnkResMain);
}
delDeleteFile(System.IO.Path.GetTempPath() + "img1");
}