| class Base64Class
rem Const
dim sBASE_64_CHARACTERS'转化码
dim lenString '计算字符串的长度
dim iCount '计数器
dim returnValue '返回值
dim tempChar'缓存字符
dim tempString'缓存字符串
dim paramString '参数字符串
dim temHex'缓存缓存十六进制
dim tempLow'缓存低位
dim tempHigh'缓存高位
dim mod3String'
dim mod4String'
dim tempBinary'
dim tempByteOne'
dim tempByteTwo'
dim tempByteThree'
dim tempByteFour'
dim tempSaveBitsOne'
dim tempSaveBitsTwo'
'********************************************
'begin初始化类
'********************************************
private sub Class_Initialize()
sBASE_64_CHARACTERS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" end sub
'********************************************
'end初始化类 '
******************************************** '********************************************
'begin销毁类
'********************************************
Private Sub Class_Terminate()
sBASE_64_CHARACTERS="" end sub
'********************************************
'end销毁类
'******************************************** '********************************************
'begin将Ansi编码的字符串进行Base64编码
'********************************************
public function Encode(paramString)
tempString=""
returnValue=""
lenString=len(paramString)
if lenString<1 then
Encode=returnValue
else
mod3String=lenString mod 3
'补足位数是为了便于计算
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处理最后剩余的几个字符
if mod3String>0 then
tempBinary = Mid(paramString, iCount, mod3String)
if mod3String=1 then
tempString = tempBinary & Chr(64) & Chr(64) & Chr(64) '用号补足位数
else tempString = tempBinary & Chr(64) & Chr(64) '用号补足位数
end if
returnValue=returnValue & tempString
end if
'*************************end处理最后剩余的几个字符
Encode=returnValue end if end function
'********************************************
'end将Ansi编码的字符串进行Base64编码
'******************************************** '********************************************
'end将Base64编码字符串转换成Ansi编码的字符串
'********************************************
public function Decode(paramString)
tempString=""
returnValue=""
lenString=len(paramString)
if lenString<1 then
Decode=returnValue
else
mod4String=lenString mod 4
if mod4String >0 then '字符串长度应当是4的倍数
Decode=returnValue
else 'begin判断是不是号
if Mid(paramString, lenString-1, 1) = "" then
mod4String=2
end if
if Mid(paramString, lenString-2, 1) = "" then
mod4String=1
end if
'end判断是不是号
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 '处理最后剩余的几个字符
if mod4String > 0 then
tempString=left(right(paramString,4),mod4String)
returnValue = returnValue & tempString
end if
Decode=returnValue
end if
end if
end function
'********************************************
'end将Base64编码字符串转换成Ansi编码的字符串
'******************************************** end class |
