软件教程

详解ASP中缓存CACHE技术

来源： 本站    类别： 软件教程    日期： 2010/10/7

　

我认为在ASP中最好的办法是用编程实现定时刷新Cache，也就是说给Application中储存的设一个过期时间。当然，在ASP中Application对象没有这样一个ExpireTime属性。这需要用程序实现。
 

Code

  • ASP：default.asp

    <%@Language=VBScript%>
    <%    Option  Explicit%>
    <%Response.Buffer=    True%>
    <!--#include file = "conn.asp"-->
    <!--#include file = "GetCache.asp"-->
    <HTML>
        <HEAD>
            <TITLE>ASP Cache演示</TITLE>
            <META     HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=gb2312">
        </HEAD>
        <BODY>
        <h4>每隔10秒刷新Cache：</h4>
        <%
        response.Flush
        GetHTMLStream
        response.Write
        HTMLStream
        %>
        </body>
    </html>

  • ASP：getcache.asp

    <%
    Const CACHE_DEFAULT_INTERVAL = 30 '每隔30秒刷新一次cache
    Dim HTMLStream
    Dim IsExpires
    IsExpires = CacheExpires
    Function CacheExpires
            Dim strLastUpdate
        Dim result strLastUpdate = Application("LastUpdate")
            If (strLastUpdate = "") Or (CACHE_DEFAULT_INTERVAL < DateDiff("s", strLastUpdate, Now)) Then
            result =     true
            SetLastUpdateTime
        Else
            result =     false
        End If
        CacheExpires = result
    End Function

    Sub SetLastUpdateTime
        Application.Lock
        Application(    "LastUpdate") = CStr(now())
        Application.UnLock
    End Sub

    Sub GetHTMLStream
        If IsExpires Then
            UpdateHTMLStream
        End If
        HTMLStream=Application(    "CACHE_HTMLStream")
    End Sub

    Sub     UpdateHTMLStream
            dim d
        d = FetchHTMLStream
        Application.Lock
        Application(    "CACHE_HTMLStream") = d
        Application.UnLock
    End Sub

    Function     FetchHTMLStream 
            Dim rs ,strSQL, strHTML
        Set rs = CreateObject("ADODB.Recordset")
        strSQL = "select categoryID , categoryname from categories"
        rs.Open strSQL, strConn,adOpenForwardOnly,adLockReadOnly
        strHTML = strHTML & "<select name=""slt_search"">"
        while (not rs.EOF)
            strHTML = strHTML & "<option>"
            strHTML = strHTML & rs.Fields    ("categoryname")
            strHTML = strHTML &     "</option>" rs.MoveNext
        wend
        strHTML = strHTML & "</select>"
        rs.Close
        Set rs = Nothing
        FetchHTMLStream = strHTML
    End Function
    %>

  • ASP：conn.asp

    <!--METADATA NAME="Microsoft ActiveX Data Objects 2.5 Library" TYPE="TypeLib" UUID="{00000205-0000-0010-8000-00AA006D2EA4}"-->
    <%
        dim strConn
        strConn =     "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=Northwind"
    %>

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