从网上来的代码，，稍微修改了一些地方，其实用的是cache类。。

保存代码为，比如pic.asp
使用:http:///log.gif

不光是163，其实就是很多防盗连的图片都可以这个实现。

<%
'盗链判断
'IfInstr(Request.ServerVariables("http_referer"),"http://"&Request.ServerVariables("server_name")&"")=0Then
'Response.Write"非法链接"
'Response.End
'EndIf

Dimurl,body,myCache

url=Request.QueryString("url")

SetmyCache=newcache
myCache.name="picindex"&url
IfmyCache.validThen
body=myCache.value
Else
body=GetWebData(url)
myCache.addbody,dateadd("d",1,now)
EndIf

IfErr.Number=0Then
Response.CharSet="UTF-8"
Response.ContentType="application/octet-stream"
Response.BinaryWritebody
Response.Flush
Else
Wscript.EchoErr.Description
Endif

'取得数据
PublicFunctionGetWebData(ByValstrUrl)
Dimcurlpath
curlpath=Mid(strUrl,1,Instr(8,strUrl,"/"))
DimRetrieval
SetRetrieval=Server.CreateObject("Microsoft.XMLHTTP")
WithRetrieval
.Open"Get",strUrl,False,"",""
.setRequestHeader"Referer",curlpath
.Send
GetWebData=.ResponseBody
EndWith
SetRetrieval=Nothing
EndFunction


'cache类

classCache
privateobj'cache内容
privateexpireTime'过期时间
privateexpireTimeName'过期时间application名
privatecacheName'cache内容application名
privatepath'url

privatesubclass_initialize()
path=request.servervariables("url")
path=left(path,instrRev(path,"/"))
endsub

privatesubclass_terminate()
endsub

publicpropertygetblEmpty
'是否为空
ifisempty(obj)then
blEmpty=true
else
blEmpty=false
endif
endproperty

publicpropertygetvalid
'是否可用(过期)
ifisempty(obj)ornotisDate(expireTime)then
valid=false
elseifCDate(expireTime)<nowthen
valid=false
else
valid=true
endif
endproperty

publicpropertyletname(str)
'设置cache名
cacheName=str&path
obj=application(cacheName)
expireTimeName=str&"expires"&path
expireTime=application(expireTimeName)
endproperty

publicpropertyletexpires(tm)
'重设置过期时间
expireTime=tm
application.lock
application(expireTimeName)=expireTime
application.unlock
endproperty

publicsubadd(var,expire)
'赋值
ifisempty(var)ornotisDate(expire)then
exitsub
endif
obj=var
expireTime=expire
application.lock
application(cacheName)=obj
application(expireTimeName)=expireTime
application.unlock
endsub

publicpropertygetvalue
'取值
ifisempty(obj)ornotisDate(expireTime)then
value=null
elseifCDate(expireTime)<nowthen
value=null
else
value=obj
endif
endproperty

publicsubmakeEmpty()
'释放application
application.lock
application(cacheName)=empty
application(expireTimeName)=empty
application.unlock
obj=empty
expireTime=empty
endsub

publicfunctionequal(var2)
'比较
iftypename(obj)<>typename(var2)then
equal=false
elseiftypename(obj)="Object"then
ifobjisvar2then
equal=true
else
equal=false
endif
elseiftypename(obj)="Variant()"then
ifjoin(obj,"^")=join(var2,"^")then
equal=true
else
equal=false
endif
else
ifobj=var2then
equal=true
else
equal=false
endif
endif
endfunction
endclass
%>