The first step, established an engineering, reference Winsock (Visual Basic is best playing SP6, otherwise MS has a bug), omitted here
In the second step, the specific implementation code Step 1: Send a request
Description:
(1) Simple adoption of the judgment already has the same name file to indicate whether there is a breakpoint.
(2) Download address, size, and downloaded bytes are simply present in the INI file, safer practice this article does not discuss
Interested friends can contact me
'------------------------------------- -------------------------------
'Name: Downloadfile
'Author: REKER 2004/3/20
'DESC: Connect the remote host, send a receiving file request, wait for a remote host response
'Params: None
'History: None
'------------------------------------- -------------------------------
Private sub downloadFile ()
ON Error ResMe next
StartTime = Time ()
WITH WINSCK
.Remotehost = host 'distal host address
.Remoteport = 80
.Connect
'Waiting for the server connection
Do while .state <> SCKCONNECTED
Doevents: doevents: doevents: doevents
'20 second timeout
IF Datediff ("S", StartTime, Time ())> 20 THEN
ShowInfo "Connection timeout"
.Close
EXIT SUB
END IF
Loop
'Send download file request
'Use HTTP / 1.0 protocol here
STRCOMMAND = "get" UpdateURL "http / 1.0" vbcrlf "download address
STRCOMMAND = STRCOMMAND "accept: * / *" vbcrlf "Don't
STRCOMMAND = STRCOMMAND "Accept: text / html" VBCRLF 'This sentence can not
STRCOMMAND = STRCOMMAND VBCRLF
STRCOMMAND = STRCOMMAND & "Host:" & Host & VBCRLF
If Dir (SaveFileName) <> "" "" ""
DIM Confirm
Confirm = msgbox ("There is already a file, whether it is broken?", Vbyesno Vbquestion, "Tips")
IF confirm = Vbyes Then
DownPosition = ""
IF not OfileCtrl.readKeyFromini ("Update", "Downsize", AppPath "Update.ini", DownPosition THEN
'Read the number of bytes downloaded last time
MSGBOX "Read size error", vbinformation, "prompt" endiff
'Send a breakdown
STRCOMMAND = STRCOMMAND & "Range: Bytes =" & ClNG (DownPosition) & "-" & VBCRLF
Else
Kill SaveFileName 'Delete the original file
END IF
END IF
STRCOMMAND = STRCOMMAND & "Connection: Keep-alive" & vbcrlf
STRCOMMAND = STRCOMMAND & VBCRLF
.Senddata strcommand
End with
IF Err THEN
LBLPROCESSRESULT.CAPTION = LBLPROCESSRESULT.CAPTION & VBCRLF & VBCAPTION & VBCRLF & VBCAPTION & VBCRLF & VBCRLF & "Download File error:" & Err.Description
LBLPROCESSRESULT.REFRESH
END IF
End Sub
Step 2, specific implementation code Step 2: Receive data
'------------------------------------- -------------------------------
'Name: Winsck_DataArrival
'Author: REKER 2004/3/20
'DESC:
'Params: 略
'Return: None
'History: None
'------------------------------------- -------------------------------
Private sub winsck_dataarrival (byval Bytestotal As Long)
ON Error ResMe next
'Doevents: doevents
Dim Bytedata () AS Byte
Winsck.getdata Bytedata (), VBBYTE
ReceiveData = ReceiveData & strconv (Bytedata (), Vbunicore
If INSTR (1, ReceiveData, "Content-length:")> 0 and filesize = 0 Then 'only the first calculation, FileSize = 0
DIM POS1 AS Long, Pos2 As Long
POS1 = INSTR (1, ReceiveData, "Content-Length:")
POS2 = INSTR (POS1 16, ReceiveData, VBCRLF)
IF Pos2> Pos1 Then
FileSizeByte = MID (ReceiveData, POS1 16, POS2 - POS1 - 16) 'calculating the length of the file
STARTTIME = Timer () 'Save the time to start downloading
Progssbar.max = filesizebyte 'Setting progress bar
FileSize = FormatNumber (FileSizebyTe / 1024, 2) 'in KB
SHOWINFO "Document Total" CSTR (FileSize) "KB ..." End IF
END IF
'The data to find the data returned from the server to find the start position of the download file
If FileHeaderlen = 0 THEN
For i = 0 to ubound (bytedata ()) - 3
IF BYTEDATA (I) = 13 and bytedata (i 1) = 10 and bytedata (i 2) = 13 and bytedata (i 3) = 10 THEN
STARTPOS = i 4 'Save the length of the file header
FileHeaderlen = StartPOS
EXIT for
END IF
'Doevents
Next I
END IF
FileSizeHavedown = bytestotal FileSizehavedown - FileHeaderlen
'Download the file length, you need to subtract the file header of the response
DBLDownloadSpeed = FormatNumber (FormatNumber (FileSizehavedown / 1024, 2) / (FormatNumber ((TimatNumber), 4), 2)
If DBLDOWNLOADSPEED <> 0 THEN 'calculates the remaining download time
SrestTime = GetrestTime (ClNG ((FileSize - (FileSizeHaveDown / 1024) / dbldownloadSpeed)) 'This procedure is slightly, you can delete this code
LabrestTime.caption = "Remaining Time: o" Sresttime
LabrestTime.Refresh
END IF
LabDownloadSpeed.caption = CSTR (DBLDownloadSpeed) "KB / S"
LabDownloadSpeed.refresh
ProgssBar.Value = filesishavedown
'Write data
Fnum = freefile ()
Open Savefilename for binary lock write as #fnum
If Lof (Fnum)> 0 THEN
Seek #fnum, lof (fnum) 1
END IF
IF StartPos> 0 THEN
For i = startpos to ubound (Bytedata ())
Put #fnum,, Bytedata (i)
Next I
Else
Put #fnum,, Bytedata ()
END IF
Close #fnum
IF Err THEN
LBLPROCESSRESULT.CAPTION = LBLPROCESSRESULT.CAPTION & VBCRLF & Get Data Error: "& Err.Description
LBLPROCESSRESULT.REFRESH
END IF
End Sub
