HTTP Protocol Downloading.

[jejacks0n]

Ok, here's the situation..

I want to download multiple files using the http protocol.

I know how to download a webpage and save it to a file using the inet.openURL/byteArray method, I know how to ftp files using the inet.execute "get/put" commands, and I know how to do a dialog free download.

But I'm unsatisfied using any of these methods to download an actual file (something larger then 10k) using http. Perhaps there is an easy answer that I've just overlooked, but...

Anyway, here are the methods that I've tried. This is a nice tutorial even if I don't get an answer. =).

Dialog Free Download method:
This is nice, it's fast and useful for small files, but it disables the form while the file is being transfered. This means if it's downloading a large file it will halt the form altogether until it's completed that download. Not very useful for what I need.

This is the code and usage, if there's any way to fix this please post.


Private Declare Function URLDownloadToFile Lib "urlmon" Alias _
"URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As _
String, ByVal szFileName As String, ByVal dwReserved As Long, _
ByVal lpfnCB As Long) As Long

For i = 0 to totaldownload
DownloadFile ("http://foobar.file" & i, "c:\bleah.file")
Next i

Public Function DownloadFile(URL As String, LocalFilename As _
String) As Boolean
Dim lngRetVal As Long
lngRetVal = URLDownloadToFile(0, URL, LocalFilename, 0, 0)
If lngRetVal = 0 Then DownloadFile = True
End Function


Inet.OpenURL method:
This works nicely, you can add a progress bar and trap any errors, but writing to the file takes almost as long as the download time. If you remove the "DoEvents" from the For/Next statement it's a bit faster but still takes a long time. This is very usefull if you are downloading a web page document or something small, but not for larger files.

Code and usage. Any suggestions?


Dim byte As String
Dim b() As Byte
Dim o As Long

For i = 0 to totaldownload
b() = Inet.OpenURL("http://foobar.file" & i, icByteArray)

Open "c:\bleah.file" For Output As #1
For o = 0 To UBound(b) - 1
DoEvents
byte = byte + Chr(b(o))
Next o
Print #1, byte
Close #1
Next i

[FirePoweR]

This is what I use to download off of the internet:
Make sure you have a label on the form called "lblStats" if you want a percentage done.


Option Explicit
Public DlFile As String

Private Sub Inet1_StateChanged(ByVal State As Integer)
Dim bDone As Boolean: bDone = False
Dim Dat() As Byte, ff As Long
Dim FileSize As Double

Select Case State
Case icResponseCompleted ' 12
DoEvents
Dat() = Inet1.GetChunk(1024, icByteArray)

If UBound(Dat) <= 0 Then
bDone = True
End If

FileSize = Val(Inet1.GetHeader("Content-Length:"))

fs = FreeFile
'Make DlFile a public variable and put the file name in it
Open DlFile For Binary Access Write As #ff

Put #ff, , Dat()

Do While Not bDone
Dat() = Inet1.GetChunk(1024, icByteArray)

Put #ff, , Dat()

'make a label for the status
If FileSize > 0 Then lblStats = Int((FileSize / LOF(1)) * 100) & "%"

If UBound(Dat) <= 0 Then
'If so, set the flag to indicate that we are done
bDone = True
End If
Loop
Close #ff
End Select
End Sub

Public Function CheckPath(FilePath As String) As Boolean
FilePath = UCase(Trim(FilePath))
On Error GoTo ErrH
If (GetAttr(FilePath) And vbDirectory) <> 0 Then
CheckPath = True
Exit Function
End If
If Dir(FilePath) <> "" Then
CheckPath = True
Else
CheckPath = False
End If
Exit Function
ErrH:
CheckPath = False
End Function

Public Sub DownloadFile(URL As String, LocalFilename As String)
Dim Headerz As String

Headerz = "Referer: " & URL & vbCrLf & "User-Agent: PowerWeb (compatible; MSIE 4.01; Windows 98)" & vbCrLf & vbCrLf
DlFile = LocalFilename
If CheckPath(DlFile) Then Kill DlFile
Inet1.Execute URL, "GET", , vbCrLf & vbCrLf & Headerz
Do Until Inet1.StillExecuting = False
DoEvents
Loop
End Sub



If you want to be able to still use the form while its downloading then take out this in the DownloadFile function:

Do Until Inet1.StillExecuting = False
DoEvents
Loop


Hope that helps...