Example of HTTP file transfer

[BobAchgill]

Can you point me to a simple VB .NET example of how to
receive a file from a web server using a HTTP method
available in .NET

Bob

 

[Ken Tucker [MVP]]

Hi,

Here is a quick example. Add these import statements.

Imports System.Net

Imports System.IO



Sample code



Dim request As WebRequest

Dim response As WebResponse

Dim reader As Stream

Dim writer As Stream

Dim data(1023) As Byte

Dim count As Integer

Dim total As Integer

Me.Show()

Me.Text = "Downloading file ....."

Application.DoEvents()

request =
WebRequest.Create("http://www.onteorasoftware.com/downloads/multigrids.zip")

response = request.GetResponse()

reader = response.GetResponseStream()

ProgressBar1.Maximum = CInt(response.ContentLength)

ProgressBar1.Value = 0

total = 0

writer = File.Create("mylocaldata.zip")

While True

count = reader.Read(data, 0, 1024)

If count <= 0 Then

Exit While

End If

writer.Write(data, 0, count)

total += 1024

If total < ProgressBar1.Maximum Then ProgressBar1.Value = total

Application.DoEvents()

End While

reader.Close()

writer.Close()



Ken

--------------------------

Can you point me to a simple VB .NET example of how to
receive a file from a web server using a HTTP method
available in .NET

Bob

 

[BobAchgill]

Beautiful! Thanks Ken.

Is it possible to get a files detail list, too, with HTTP?

But, hey, I am so thankful to get what you gave... it helps me out a
whole lot!

Bob

 

[Cor Ligthert]

Bob,

I was assuming this was a double post with the webservice and it (is) was
not clear for me which you asked.

This one is a very short one for what you ask about a http webserver.
\\\\
webclient.downloadfile(url,filePath)
////
I hope this helps?

Cor

 

[BobAchgill]

So as I understand the only difference between the two methods for
downloading a file from an HTTP web site is:
- webclient.downloadfile(url,filePath) is short and sweet and to
the point for getting the file down
- WebRequest.Create("url") lets you also do things like monitor
progress or choose to work Asyn

Do either have the ability to see the file datestamp on the server? I
guess that is asking to much of HTTP. Only FTP does datestamps.

Bob

 

[Cor Ligthert]

Bob,

To get information. It is changed in this message so when you have errors
try to correct it or reply.
There are a lot of webheaders as you see as "content-length"

\\\
dim conlength as string
Dim wbRq As DirectCast(WebRequest.Create(item.Text), HttpWebRequest)
wbRq.Timeout = 2000
Try
Dim wbRs As DirectCast(wbRq.GetResponse(), HttpWebResponse)
Dim wbHCol As WebHeaderCollection = wbRs.Headers
For i As Integer = 0 To wbHCol.Count - 1
Dim header As String = wbHCol.GetKey(i)
Dim values As String() = wbHCol.GetValues(header)
If values.Length > 0 andalso header.Tolower = "content-length" Then
conlenght = values(0)
End If
Next
wbRs.Close()
Catch
conlength = "?"
End Try
///
I hope this helps?

Cor

 

[Herfried K. Wagner [MVP]]

Dim wbRq As DirectCast(WebRequest.Create(item.Text), HttpWebRequest)

LOL!

 

[Cor Ligthert]

Bob,

Herfried saw that I used VB 2007



Here is a sample that is tested

You can see in it today that it is the last updated at
Last-Modified Tue, 01 Feb 2005 11:08:47 GMT

\\\
Public Class Herfrieds
Public Shared Sub Main()
Dim conlength As String
Dim wbRq As Net.HttpWebRequest = _
DirectCast(Net.WebRequest.Create _
("http://dotnet.mvps.org/"), Net.HttpWebRequest)
wbRq.Timeout = 2000
Try
Dim wbRs As Net.HttpWebResponse = DirectCast(wbRq.GetResponse(),
_
Net.HttpWebResponse)
Dim wbHCol As Net.WebHeaderCollection = wbRs.Headers
For i As Integer = 0 To wbHCol.Count - 1
Dim header As String = wbHCol.GetKey(i)
Dim values As String() = wbHCol.GetValues(header)
If values.Length > 0 Then
Console.Write(header)
Console.Write(" ")
Console.Write(values(0))
Console.Write(vbCrLf)
End If
Next
wbRs.Close()
Catch
Console.Write("could not get something")
End Try
End Sub
End Class
///
I hope this helps a little bit better?



Cor