在使用VBScript時,我們可以用Application緩存數組來實現緩存,例:
程序代碼:
復制代碼代碼如下:
Dim rs,arr
rs.Open conn,sql,1,1
arr=rs.GetRows()
Application.Lock()
Application("cache")=arr
Applicatoin.UnLock()
在VBScript里,數組是可以存到Application對象里的,但是如果ASP的語言選擇為JScript的話,那么就有些不妙了,我們在使用Application儲存一個數組時,會出現以下錯誤:
引用內容:
Application object, ASP 0197 (0x80004005)
Disallowed object use
Cannot add object with apartment model behavior to the application intrinsic object.
在微軟的知識庫可以找到具體原因如下:
引用內容:
JScript arrays are considered to be "Apartment" COM components. Only Component Object Model (COM) components that aggregate the Free Threaded Marshaler (FTM) can be assigned to Application scope within an Internet Information Server (IIS) 5.0 ASP page. Because an "Apartment" component cannot aggregate the FTM (it cannot allow a direct pointer to be passed to its clients, unlike a "Both with FTM" object), JScript arrays do not aggregate the FTM. Therefore, JScript arrays cannot be assigned to Application scope from an ASP page.
以上描述引用自:PRB: Error When You Store a JScript Array in Application Scope in IIS 5.0
因此,為了解決這個問題,在Google里找了一大會,終于找到了一篇文章《Application對象的Contents和StaticObjects做Cache的一些結論》,解決了這個問題,方法就是使用Application.StaticObject存放一個Scripting.Dictionary對象,然后再使用Scripting.Dictionary對象來存放需要緩存的數據。
據此,寫了一個操作緩存的類,實現put、get、remove和clear方法,使用之前,需要在global.asa中添加一個object:
程序代碼:
<object id="xbsCache" runat="server" scope="Application" progid="Scripting.Dictionary"></object>
類的實現如下:
復制代碼代碼如下:
<script language="JScript" runat="server">
/**
Title: cache operate class
Description: operate system cache
@Copyright: Copyright (c) 2007
@Author: xujiwei
@Website: http://www.xujiwei.cn/
@Version: 1.0
@Time: 2007-06-29 12:03:45
**/
var xbsCache = {
get: function(key) {
return Application.StaticObjects("xbsCache").Item("Cache."+key);
},
put: function(key, data) {
Application.Lock();
Application.StaticObjects("xbsCache").Item("Cache."+key)=data;
Application.UnLock();
},
remove: function(key) {
Application.Lock();
Application.StaticObjects("xbsCache").Remove("Cache."+key);
Application.UnLock();
},
clear: function() {
Application.Lock();
Application.StaticObjects("xbsCache").RemoveAll();
Application.UnLock();
}
}
</script>
如此,就完成了ASP中使用JScript時的緩存實現。