即：
如果有空格就用%20代替，如果有其它字符就用%ASCII代替，如果有汉字等四个字节的字符，就用两个%ASCII来代替。不过有时候我们也需要将经过这种编码的字符串进行解码，但asp并没有提供相关的函数，这给我们处理问题带来了一定的麻烦。其实我们只要知道了编码规则后，就可以用asp代码来实现我们自己的URlDecode函数了。
具体实现如下：
复制代码 代码如下:
function urldecode(encodestr)
newstr=""
havechar=false
lastchar=""
for i=1 to len(encodestr)
char_c=mid(encodestr,i,1)
if char_c="+" then
newstr=newstr & " "
elseif char_c="%" then
next_1_c=mid(encodestr,i+1,2)
next_1_num=cint("&H" & next_1_c)
if havechar then
havechar=false
newstr=newstr & chr(cint("&H" & lastchar & next_1_c))
else
if abs(next_1_num)<=127 then
newstr=newstr & chr(next_1_num)
else
havechar=true
lastchar=next_1_c
end if
end if
i=i+2
else
newstr=newstr & char_c
end if
next
urldecode=newstr
end function
下面为大家提供一个更成熟的函数：
复制代码 代码如下:
'================================================
'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
