ASP中CACHE技术1

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%>


<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

<%
dim strConn
strConn = "Provider=SQLOLEDB.1;Integrated Security=SSPI;Persist Security Info=False;Initial Catalog=Northwind"
%>

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标签:ASP中CACHE技术