Я пытаюсь преобразовать данные base64 в изображение с прокси-файлом, но код не работает.
Я добавил строку кодированных изображений base64 (base64String) в код для тестирования.
[update]
Я добавил альтернативный код ниже.Я думаю, что близко к решению, но есть проблема с кодировкой.
<% Base64Chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" & _
"abcdefghijklmnopqrstuvwxyz" & _
"0123456789" & _
"+/"
Public Function base64_decode( byVal strIn )
Dim w1, w2, w3, w4, n, strOut
For n = 1 To Len( strIn ) Step 4
w1 = mimedecode( Mid( strIn, n, 1 ) )
w2 = mimedecode( Mid( strIn, n + 1, 1 ) )
w3 = mimedecode( Mid( strIn, n + 2, 1 ) )
w4 = mimedecode( Mid( strIn, n + 3, 1 ) )
If w2 >= 0 Then _
strOut = strOut + _
Chr( ( ( w1 * 4 + Int( w2 / 16 ) ) And 255 ) )
If w3 >= 0 Then _
strOut = strOut + _
Chr( ( ( w2 * 16 + Int( w3 / 4 ) ) And 255 ) )
If w4 >= 0 Then _
strOut = strOut + _
Chr( ( ( w3 * 64 + w4 ) And 255 ) )
Next
base64_decode = strOut
End Function
Private Function mimedecode( byVal strIn )
If Len( strIn ) = 0 Then
mimedecode = -1 : Exit Function
Else
mimedecode = InStr( Base64Chars, strIn ) - 1
End If
End Function
Function StringToBinary(String)
Dim I, B
For I=1 to len(String)
B = B & ChrB(Asc(Mid(String,I,1)))
Next
StringToBinary = B
End Function
'values
base64String="data:image/gif;base64,R0lGODlhDwAPAKECAAAAzMzM///// wAAACwAAAAADwAPAAACIISPeQHsrZ5ModrLlN48CXF8m2iQ3YmmKqVlRtW4ML wWACH+H09wdGltaXplZCBieSBVbGVhZCBTbWFydFNhdmVyIQAAOw=="
filename="test"
'start
response.Expires = 0
response.Buffer = True
response.Clear
imgDataArr = split(base64String,";")
mimeType = imgDataArr(0)
imgData = split(imgDataArr(1),",")
Response.contentType =mimeType
Response.AddHeader "Content-Disposition", "attachment; filename="&filename&".gif"
Response.binaryWrite StringToBinary(Base64Decode(imgData(1)))
response.End
%>
<<< Обновленный код >>>
<% Function Base64Decode(base64String)
Const Base64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
Dim dataLength, sOut, groupBegin
base64String = Replace(base64String, vbCrLf, "")
base64String = Replace(base64String, vbTab, "")
base64String = Replace(base64String, " ", "")
dataLength = Len(base64String)
If dataLength Mod 4 <> 0 Then
Err.Raise 1, "Base64Decode", "Bad Base64 string."
Exit Function
End If
For groupBegin = 1 To dataLength Step 4
Dim numDataBytes, CharCounter, thisChar, thisData, nGroup, pOut
numDataBytes = 3
nGroup = 0
For CharCounter = 0 To 3
thisChar = Mid(base64String, groupBegin + CharCounter, 1)
If thisChar = "=" Then
numDataBytes = numDataBytes - 1
thisData = 0
Else
thisData = InStr(1, Base64, thisChar, vbBinaryCompare) - 1
End If
If thisData = -1 Then
Err.Raise 2, "Base64Decode", "Bad character In Base64 string."
Exit Function
End If
nGroup = 64 * nGroup + thisData
Next
nGroup = Hex(nGroup)
nGroup = String(6 - Len(nGroup), "0") & nGroup
pOut = Chr(CByte("&H" & Mid(nGroup, 1, 2))) + _
Chr(CByte("&H" & Mid(nGroup, 3, 2))) + _
Chr(CByte("&H" & Mid(nGroup, 5, 2)))
sOut = sOut & Left(pOut, numDataBytes)
Next
Base64Decode = sOut
End Function
Function Stream_StringToBinary(Text, chrSet)
Const adTypeText = 2
Const adTypeBinary = 1
Dim BinaryStream 'As New Stream
Set BinaryStream = CreateObject("ADODB.Stream")
'Specify stream type - we want To save text/string data.
BinaryStream.Type = adTypeText
'Specify charset For the source text (unicode) data.
If Len(chrSet) > 0 Then
BinaryStream.CharSet = chrSet
Else
BinaryStream.CharSet = "us-ascii"
End If
'Open the stream And write text/string data To the object
BinaryStream.Open
BinaryStream.WriteText Text
'Change stream type To binary
BinaryStream.Position = 0
BinaryStream.Type = adTypeBinary
'Ignore first two bytes - sign of
BinaryStream.Position = 0
Stream_StringToBinary = (BinaryStream.Read)
End Function
'values
base64String="data:image/gif;base64,R0lGODlhDwAPAKECAAAAzMzM///// wAAACwAAAAADwAPAAACIISPeQHsrZ5ModrLlN48CXF8m2iQ3YmmKqVlRtW4ML wWACH+H09wdGltaXplZCBieSBVbGVhZCBTbWFydFNhdmVyIQAAOw=="
'start
response.Expires = 0
response.Buffer = True
response.Clear
imgDataArr = split(img,";")
mimeType = imgDataArr(0)
filename="testImage"
extension = Split(imgDataArr(0),"/")(1)
imgData = split(imgDataArr(1),",")
Response.contentType = mimeType
Response.AddHeader "Content-Disposition", "attachment; filename="&filename&"."&extension
Response.CharSet = "utf-8"
Response.binaryWrite Stream_StringToBinary(Base64Decode(imgData(1)),"utf-8")
Response.End
%>