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class Base64Class
rem Const
dim sBASE_64_CHARACTERS'轉化碼
dim lenString '計算字串的長度
dim iCount '計數器
dim returnValue '傳回值
dim tempChar'緩衝字元
dim tempString'緩衝字串
dim paramString '參數字串
dim temHex'緩衝緩衝十六進位
dim tempLow'緩衝低位
dim tempHigh'緩衝高位
dim mod3String'
dim mod4String'
dim tempBinary'
dim tempByteOne'
dim tempByteTwo'
dim tempByteThree'
dim tempByteFour'
dim tempSaveBitsOne'
dim tempSaveBitsTwo'
'********************************************
'begin初始化類
'********************************************
private sub Class_Initialize()
sBASE_64_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" end sub
'********************************************
'end初始化類 '
******************************************** '********************************************
'begin銷毀類
'********************************************
Private Sub Class_Terminate()
sBASE_64_CHARACTERS="" end sub
'********************************************
'end銷毀類
'******************************************** '********************************************
'begin將Ansi編碼的字串進行Base64編碼
'********************************************
public function Encode(paramString)
tempString=""
returnValue=""
lenString=len(paramString)
if lenString<1 then
Encode=returnValue
else
mod3String=lenString mod 3
'補足位元是為了便於計算
if mod3String>0 then
lenString=lenString+3-mod3String
lenString=lenString-3
end if
'*************************begin
for iCount=1 to lenString step 3
tempBinary = Mid(paramString, iCount, 3)
'response.write tempBinary
tempByteOne= Asc(Mid(tempBinary, 1, 1)): tempSaveBitsOne = tempByteOne And 3
tempByteTwo = Asc(Mid(tempBinary, 2, 1)): tempSaveBitsTwo = tempByteTwo And 15
tempChar = Asc(Mid(tempBinary, 3, 1))
tempByteOne = Mid(sBASE_64_CHARACTERS, ((tempByteOne And 252) \ 4) + 1, 1)
tempByteTwo = Mid(sBASE_64_CHARACTERS, (((tempByteTwo And 240) \ 16) Or (tempSaveBitsOne * 16) And &HFF) + 1, 1)
tempByteThree = Mid(sBASE_64_CHARACTERS, (((tempChar And 192) \ 64) Or (tempSaveBitsTwo * 4) And &HFF) + 1, 1)
tempByteFour = Mid(sBASE_64_CHARACTERS, (tempChar And 63) + 1, 1)
tempString = tempByteOne & tempByteTwo & tempByteThree & tempByteFour returnValue=returnValue & tempString next
'*************************end
'*************************begin處理最後剩餘的幾個字元
if mod3String>0 then
tempBinary = Mid(paramString, iCount, mod3String)
if mod3String=1 then
tempString = tempBinary & Chr(64) & Chr(64) & Chr(64) '用@號補足位元
else tempString = tempBinary & Chr(64) & Chr(64) '用@號補足位元
end if
returnValue=returnValue & tempString
end if
'*************************end處理最後剩餘的幾個字元
Encode=returnValue end if end function
'********************************************
'end將Ansi編碼的字串進行Base64編碼
'******************************************** '********************************************
'end將Base64編碼字串轉換成Ansi編碼的字串
'********************************************
public function Decode(paramString)
tempString=""
returnValue=""
lenString=len(paramString)
if lenString<1 then
Decode=returnValue
else
mod4String=lenString mod 4
if mod4String >0 then '字串長度應當是4的倍數
Decode=returnValue
else 'begin判斷是不是@號
if Mid(paramString, lenString-1, 1) = "@" then
mod4String=2
end if
if Mid(paramString, lenString-2, 1) = "@" then
mod4String=1
end if
'end判斷是不是@號
if mod4String>0 then
lenString=lenString-4
end if
for iCount=1 to lenString step 4
tempString = Mid(paramString, iCount, 4)
tempByteOne = InStr(sBASE_64_CHARACTERS, Mid(tempString, 1, 1)) - 1
tempByteTwo = InStr(sBASE_64_CHARACTERS, Mid(tempString, 2, 1)) - 1
tempByteThree = InStr(sBASE_64_CHARACTERS, Mid(tempString, 3, 1)) - 1
tempByteFour = InStr(sBASE_64_CHARACTERS, Mid(tempString, 4, 1)) - 1
tempByteOne = Chr(((tempByteTwo And 48) \ 16) Or (tempByteOne * 4) And &HFF) tempByteTwo = "" & Chr(((tempByteThree And 60) \ 4) Or (tempByteTwo * 16) And &HFF)
tempByteThree = Chr((((tempByteThree And 3) * 64) And &HFF) Or (tempByteFour And 63))
tempString=tempByteOne & tempByteTwo & tempByteThree
returnValue=returnValue & tempString
next
'******************************end '處理最後剩餘的幾個字元
if mod4String > 0 then
tempString=left(right(paramString,4),mod4String)
returnValue = returnValue & tempString
end if
Decode=returnValue
end if
end if
end function
'********************************************
'end將Base64編碼字串轉換成Ansi編碼的字串
'******************************************** end class |
