ASP的URLDecode函数URLEncode解码函数

我们知道，ASP的Server对象有个URLEncode方法可以对地址进行编码，但却没有相应的解码函数，下边的这个函数可以实现对URLEncode的解码。
下面的代码是从kesion系统扒下的，确实不错，支持utf8格式。
 

'================================================ 
'函数名：URLDecode 
'作 用：URL解码 
'================================================ 

 

Function URLDecode(ByVal urlcode) 
Dim start,final,length,char,i,butf8,pass 
Dim leftstr,rightstr,finalstr 
Dim b0,b1,bx,blength,position,u,utf8 
On Error Resume Next 

b0 = Array(192,224,240,248,252,254) 
urlcode = Replace(urlcode,"+"," ") 
pass = 0 
utf8 = -1 

length = Len(urlcode) : start = InStr(urlcode,"%") : final = InStrRev(urlcode,"%") 
If start = 0 Or length < 3 Then URLDecode = urlcode : Exit Function 
leftstr = Left(urlcode,start - 1) : rightstr = Right(urlcode,length - 2 - final) 

For i = start To final 
char = Mid(urlcode,i,1) 
If char = "%" Then 
bx = URLDecode_Hex(Mid(urlcode,i + 1,2)) 
If bx > 31 And bx < 128 Then 
i = i + 2 
finalstr = finalstr & ChrW(bx) 
ElseIf bx > 127 Then 
i = i + 2 
If utf8 < 0 Then 
butf8 = 1 : blength = -1 : b1 = bx 
For position = 4 To 0 Step -1 
If b1 >= b0(position) And b1 < b0(position + 1) Then 
blength = position 
Exit For 
End If 
Next 
If blength > -1 Then 
For position = 0 To blength 
b1 = URLDecode_Hex(Mid(urlcode,i + position * 3 + 2,2)) 
If b1 < 128 Or b1 > 191 Then butf8 = 0 : Exit For 
Next 
Else 
butf8 = 0 
End If 
If butf8 = 1 And blength = 0 Then butf8 = -2 
If butf8 > -1 And utf8 = -2 Then i = start - 1 : finalstr = "" : pass = 1 
utf8 = butf8 
End If 
If pass = 0 Then 
If utf8 = 1 Then 
b1 = bx : u = 0 : blength = -1 
For position = 4 To 0 Step -1 
If b1 >= b0(position) And b1 < b0(position + 1) Then 
blength = position 
b1 = (b1 xOr b0(position)) * 64 ^ (position + 1) 
Exit For 
End If 
Next 
If blength > -1 Then 
For position = 0 To blength 
bx = URLDecode_Hex(Mid(urlcode,i + 2,2)) : i = i + 3 
If bx < 128 Or bx > 191 Then u = 0 : Exit For 
u = u + (bx And 63) * 64 ^ (blength - position) 
Next 
If u > 0 Then finalstr = finalstr & ChrW(b1 + u) 
End If 
Else 
b1 = bx * &h100 : u = 0 
bx = URLDecode_Hex(Mid(urlcode,i + 2,2)) 
If bx > 0 Then 
u = b1 + bx 
i = i + 3 
Else 
If Left(urlcode,1) = "%" Then 
u = b1 + Asc(Mid(urlcode,i + 3,1)) 
i = i + 2 
Else 
u = b1 + Asc(Mid(urlcode,i + 1,1)) 
i = i + 1 
End If 
End If 
finalstr = finalstr & Chr(u) 
End If 
Else 
pass = 0 
End If 
End If 
Else 
finalstr = finalstr & char 
End If 
Next 
URLDecode = leftstr & finalstr & rightstr 
End Function 

Function URLDecode_Hex(ByVal h) 
On Error Resume Next 
h = "&h" & Trim(h) : URLDecode_Hex = -1 
If Len(h) <> 4 Then Exit Function 
If isNumeric(h) Then URLDecode_Hex = cInt(h) 
End Function