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<!–
为了提高网站首页的性能,首页凡是需要调用数据库显示数据的地方都会先试图从缓存中调用数据,
如果缓存中没有可用数据再打开数据库取出记录集,为了让页面显示数据和数据库在一定时间内同步,
我们把缓存的过期时间设置成30秒.
声明:缓存管理类出自于动网论坛7.0
注意:最好不要在缓存里直接缓存带状态的对象和mta模式的对象,比如说直接缓存记录集或者数据库链接对象等.
–>
<%
sub showrsarr(rsarr)
2005-1-27 by 蛙蛙王子
用表格显示记录集getrows生成的数组的表结构
response.write "<table width=100% border=0 cellspacing=0 cellpadding=0>"
if not isempty(rsarr) then
for y=0 to ubound(rsarr,2)
response.write"<tr>"
for x=0 to ubound(rsarr,1)
response.write "<td>"&rsarr(x,y)&"</td>"
next
response.write"</tr>"
next
else
response.write "<tr>"
response.write "<td colspan="&rs.fields.count-1&">no records</td>"
response.write "</tr>"
end if
response.write "</table>"
end sub
class cls_cache
rem ==================使用说明=================================================================================
rem = 本类模块是动网先锋原创，作者：迷城浪子。如采用本类模块，请不要去掉这个说明。这段注释不会影响执行的速度。=
rem = 作用：缓存和缓存管理类 =
rem = 公有变量：reloadtime 过期时间（单位为分钟）缺省值为14400, =
rem = maxcount 缓存对象的最大值，超过则自动删除使用次数少的对象。缺省值为300 =
rem = cachename 缓存组的总名称，缺省值为"dvbbs",如果一个站点中有超过一个缓存组，则需要外部改变这个值。 =
rem = 属性:name 定义缓存对象名称，只写属性。 =
rem = 属性:value 读取和写入缓存数据。 =
rem = 函数：objisempty()判断当前缓存是否过期。 =
rem = 方法：delcahe(mycahename)手工删除一个缓存对象，参数是缓存对象的名称。 =
rem ===========================================================================================================
public reloadtime,maxcount,cachename
private localcachename,cachedata,delcount
private sub class_initialize()
reloadtime=14400
cachename="dvbbs"
end sub
private sub setcache(setname,newvalue)
application.lock
application(setname) = newvalue
application.unlock
end sub
private sub makeempty(setname)
application.lock
application(setname) = empty
application.unlock
end sub
public property let name(byval vnewvalue)
localcachename=lcase(vnewvalue)
end property
public property let value(byval vnewvalue)
if localcachename<>"" then
cachedata=application(cachename&"_"&localcachename)
if isarray(cachedata) then
cachedata(0)=vnewvalue
cachedata(1)=now()
else
redim cachedata(2)
cachedata(0)=vnewvalue
cachedata(1)=now()
end if
setcache cachename&"_"&localcachename,cachedata
else
err.raise vbobjecterror + 1, "dvbbscacheserver", " please change the cachename."
end if
end property
public property get value()
if localcachename<>"" then
cachedata=application(cachename&"_"&localcachename)
if isarray(cachedata) then
value=cachedata(0)
else
err.raise vbobjecterror + 1, "dvbbscacheserver", " the cachedata is empty."
end if
else
err.raise vbobjecterror + 1, "dvbbscacheserver", " please change the cachename."
end if
end property
public function objisempty()
objisempty=true
cachedata=application(cachename&"_"&localcachename)
if not isarray(cachedata) then exit function
if not isdate(cachedata(1)) then exit function
if datediff("s",cdate(cachedata(1)),now()) < 60*reloadtime then
objisempty=false
end if
end function
public sub delcahe(mycahename)
makeempty(cachename&"_"&mycahename)
end sub
end class
dim strconn,rs
strconn="driver={sql server};server=localhost;database=northwind;uid=sa;pwd=sa;"
public function getemployees()
dim sql,rs,cache
set cache=new cls_cache
cache.reloadtime=0.5
cache.cachename="wawa"
cache.name="employees"
if cache.objisempty() then
set rs=server.createobject("adodb.recordset")
sql = "select employeeid, lastname, firstname from employees order by employeeid desc"
rs.open sql,strconn,1,1
cache.value = rs.getrows(5)
rs.close:set rs=nothing
end if
getemployees=cache.value
set cache=nothing
end function
showrsarr(getemployees)
%>
<script>
function timeout(a){
var c=a-1;
if(c==0) {
window.location.href=window.location;
}else{
document.all.abc.innerhtml="离缓存结束还有："+c+"秒";
window.settimeout(timeout(+c+),1000);
}
}
</script>
<body onload="timeout(30)">
<div id="abc"></div>
