文章说明.txt

xml缓存类试用版用于ASP

可选标题：
实践xml缓存技术构建高性能web站点
利用xml缓存技术给数据库减压
xml缓存类

关键词：xml缓存,高性能web站点,数据库减压,xml缓存类

正文：

打造一个高性能稳定的web站点一直是站长和程序员的梦想，本文用作者的一次亲身经历的来说说如何利用xml缓存技术实现站点的高性能。
我是从今年开始做138手机主题网的，采用SQL2000做为数据库，开发语言用的是Asp，查询的时候都是动态查询，直接用like %的方式，那个时候反正一天的访问量小，同时在线的时候也就几十个人而已，所以服务器也就能胜任要求，随着访问量慢慢增加，当同时在线达到几百人时，此时服务器开始不堪重负，CPU常常达到100%不降，网页打开速度也超级慢，一个查询页面需要几秒钟甚至更长，于是我开始考虑优化程序和数据库，数据库建立索引，不是很理想，因为用的是like '% 这种方式，于是我想到了缓存，而xml本身的特点决定了他非常适合做数据库的缓存，好东西不敢独享，特发布出来，以便同行交流，共同进步。
实现的思路是这样的：程序读取信息时，先判断是否缓存了xml数据，如果有，则直接从xml中读取信息，否则从数据库中读取，并将此次结果生成xml文件，以便以后调用，加快速度，同时判断xml缓存文件是否过期，如果过期则需要重新生成xml。下面是具体的代码。

xmlcachecls.asp
<%
Rem xml数据缓存类
'--------------------------------------------------
'转载的时候请保留版权信息
'作者:walkman
'网址:手机主题 http://www.shouji138.com
'版本:ver1.0
'欢迎各位交流进步
'--------------------------------------------------

Class XmlCacheCls

	Rem 私有变量定义
	Private m_CacheTime		'缓存时间，单位秒
	Private m_PageSize		'每页大小
	Private m_CachePageNum	'xml缓存页大小
	Private m_XmlFile		'xml路径，用绝对地址,不需要加扩展名
	Private m_Sql			'SQL语句
	Private m_TableName		'表名或者视图名
	Private m_Columns		'列名 用,隔开
	Private m_CurPage		'当前页
	Private m_CacheType		'缓存类型：1,列表 2,详情
	Private m_DataConn		'数据源,必须已经打开
	Private m_QueryType		'查询类型：1,直接用sql 2,用存储过程

	Private m_SQLArr		'返回的数据数组
	Private m_RecordCount
	
	
	Rem 公共属性

	'缓存时间
	Public Property Let  CacheTime(v)
		m_CacheTime = v 
	End Property

	Public Property Get  CacheTime
		CacheTime = m_CacheTime 
	End Property

	
	'每页大小
	Public Property Let  PageSize(v)
		m_PageSize = v 
	End Property

	Public Property Get  PageSize
		PageSize = m_PageSize 
	End Property



	'xml缓存页大小
	Public Property Let  CachePageNum(v)
		m_CachePageNum = v 
	End Property

	Public Property Get  CachePageNum
		CachePageNum = m_CachePageNum 
	End Property



	'xml路径，用绝对地址
	Public Property Let  XmlFile(v)
		m_XmlFile = v 
	End Property

	Public Property Get  XmlFile
		XmlFile = m_XmlFile 
	End Property


	'xml路径，用绝对地址
	Public Property Let  Sql(v)
		m_Sql = v 
	End Property

	Public Property Get  Sql 
		Sql = m_Sql 
	End Property


	'表名或者视图名
	Public Property Let  TableName(v)
		m_TableName = v 
	End Property

	Public Property Get  TableName 
		TableName = m_TableName 
	End Property



	'列名 用,隔开
	Public Property Let  Columns(v)
		m_Columns = v 
	End Property

	Public Property Get  Columns 
		Columns = m_Columns 
	End Property

	
	'当前页
	Public Property Let  CurPage(v)
		m_CurPage = v 
	End Property

	Public Property Get  CurPage 
		CurPage = m_CurPage 
	End Property


	
	'缓存类型：1,列表 2,详情
	Public Property Let  CacheType(v)
		m_CacheType = v 
	End Property

	Public Property Get  CacheType 
		CacheType = m_CacheType 
	End Property



	'缓存类型：1,列表 2,详情
	Public Property Set  Conn(v)
		Set m_DataConn = v 
	End Property

	Public Property Get  Conn 
		Conn = m_DataConn 
	End Property


	'返回记录总数
	Public Property Get  RecordCount 
		RecordCount = m_RecordCount 
	End Property

	'返回记录数组
	Public Property Get  SQLArr 
		SQLArr = m_SQLArr 
	End Property


	Rem 公共方法 读取数据
	Public Function ReadData
		If m_CacheType = 1 Then 
			ReadListAndSearchData
		Else 
			ReadContentData
		End If 
	End Function 
	
	Rem 读取详情信息
	Private Function ReadContentData
		Dim xmlfile
		xmlfile = m_XmlFile
		If FSOExistsFile(xmlfile) Then	'存在xml缓存，直接从xml中读取
			ReadContentDataFromXml xmlfile
		Else
			ReadContentDataFromDB
		End If 
	End Function 
	
	Rem 从xml文件读取详情信息
	Private Function ReadContentDataFromXml(xmlfile)
		Dim SQLARR()
		Dim XmlDoc
		Set XmlDoc = Server.CreateObject("msxml2.FreeThreadedDOMDocument.3.0")
		XmlDoc.Load xmlfile 
		Dim itemslength,itemsi
		itemslength = XmlDoc.documentElement.childNodes.length

		For itemsi=0 To itemslength-1
			ReDim Preserve SQLARR(itemslength-1,0)
			SQLARR(itemsi,0) = XmlDoc.documentElement.childNodes(itemsi).text
		Next 
		Set XmlDoc = Nothing 
		m_SQLArr = SQLArr
	End Function 
	

	Rem 从Db中读取详情信息
	Private Function ReadContentDataFromDB()
		Dim rs
		Dim SQLARR
		Set rs = m_DataConn.execute(m_sql)
		IF Not Rs.eof Then
			SQLArr=Rs.GetRows(1)
			rs.close
			Set rs = Nothing
		Else
			rs.close
			Set rs = Nothing
			Exit Function 
		End If 
		m_SQLArr = SQLArr
	End Function 


	Rem 读取列表数据
	Private Function ReadListAndSearchData
		Dim sPagesize,TotalPage,CurPage,TotalRec
		sPagesize = m_PageSize * m_CachePageNum

		m_CurPage = CLng(m_CurPage)
		
		If m_CurPage Mod m_CachePageNum = 0 Then 
			CurPage = m_CurPage/m_CachePageNum
		Else
			CurPage = int(clng(m_CurPage)/m_CachePageNum)+1
		End If 

		Dim xmlfile
		xmlfile = getXmlFileName(CurPage)
		If FSOExistsFile(xmlfile) Then	'存在xml缓存，直接从xml中读取
			ReadListAndSearchDataFromXml xmlfile
		Else
			ReadListAndSearchDataFromDB
		End If 
	End Function 

	Rem 从xml中读列表数据
	Private Function ReadListAndSearchDataFromXml(xmlfile)
		Dim SQLARR()
		Dim XmlDoc
		Set XmlDoc = Server.CreateObject("msxml2.FreeThreadedDOMDocument.3.0")
		XmlDoc.Load xmlfile 
		Dim totalrecont
		totalrecont = XmlDoc.documentElement.selectSingleNode("totalrec").text
		m_RecordCount = totalrecont
		Dim TotalRec
		TotalRec = m_RecordCount
		If totalrecont = 0 Then 
			Set XmlDoc = Nothing
			m_SQLArr = SQLARR
			Exit Function 
		End If 

		Dim TotalPage,curpage
		curpage = m_CurPage
		If m_CurPage Mod m_CachePageNum = 0 Then 
			CurPage = m_CurPage/m_CachePageNum
		Else
			CurPage = int(clng(m_CurPage)/m_CachePageNum)+1
		End If 

		If TotalRec Mod m_CachePageNum =0 Then 
			TotalPage = totalrecont/m_CachePageNum
		Else
			TotalPage = int(clng(totalrecont)/m_CachePageNum)+1
		End If 
		
		If curpage>TotalPage Then curpage=TotalPage
		Dim starti
		Dim startn
		startn = m_curpage - (curpage-1) * m_CachePageNum
		Rem 计算开始位置
		starti = (startn-1) * m_pagesize
		Dim items,item
		Set items = XmlDoc.documentElement.SelectNodes("item")
		Dim i
		Dim num
		Dim length
		length = items.length
		num = 0
		For i = starti To m_PageSize + starti -1
			If i >=length Then Exit For 
			Set item = items(i)
			Dim attrlength
			attrlength = item.attributes.length
			ReDim Preserve SQLARR(attrlength,num)
			Dim Attribute
			Dim Attributei
			Attributei = 0
			For Attributei = 0 To attrlength-1
				SQLArr(Attributei,num) = item.attributes(Attributei).Nodevalue
			Next 		
			num = num + 1
		Next 
		Set XmlDoc = Nothing 
		m_SQLArr = SQLArr
	End Function 
	
	Rem 从DB中读列表数据
	Private Function ReadListAndSearchDataFromDB
		Dim rs,TotalRec,CurPage
		CurPage = m_CurPage
		Set Rs = Server.CreateObject("Adodb.Recordset")
		Rs.open m_sql,m_DataConn,1
		TotalRec = rs.recordcount
		m_RecordCount = TotalRec
		rs.pagesize = m_PageSize
		If  CurPage>rs.PageCount Then  CurPage = rs.PageCount
		If Not rs.eof Then rs.absolutePage=m_CurPage
		Dim SQLARR()
		Dim k
		k = 0
		While Not rs.eof and k<m_PageSize
			Dim fieldlegth
			fieldlegth = rs.Fields.count
			ReDim Preserve SQLARR(fieldlegth,k)
			
			Dim fieldi
			For fieldi = 0 To fieldlegth-1
				SQLArr(fieldi,k) = rs.Fields(fieldi).value
			Next 
			rs.movenext
			k=k+1
		Wend 
		rs.close
		Set rs = Nothing 
		m_SQLArr = SQLArr
	End Function 


	Rem 获取xml文件名称
	Private Function getXmlFileName(num)
		Dim tmpstr
		tmpstr = LCase(m_XmlFile)
		If Right(tmpstr,4) = ".xml" Then
			tmpstr = Left(tmpstr,Len(tmpstr)-Len(".xml"))
		End If 
		tmpstr = Replace(tmpstr,"%","_")
		tmpstr = tmpstr & "_" & num & ".xml"
		getXmlFileName = tmpstr
	End Function 

	
	Rem 公共方法 将数据写入xml文件
	Public Function WriteDataToXml
		If m_CacheType = 1 Then 
			WriteListAndSearchDataToXml
		Else 
			WriteContentDataToXml
		End If 
	End Function 


	Rem 写具体某条信息的详情xml
	Private Function WriteContentDataToXml
		Rem xml未过期则直接退出
		Dim xmlfile
		xmlfile = m_XmlFile
		If FSOExistsFile(xmlfile) Then
			If Not isXmlCacheExpired(xmlfile,m_CacheTime) Then  Exit Function 
		End If 
		Dim rs
		Set rs = Server.CreateObject("Adodb.Recordset")

		Rs.open m_sql,m_DataConn
		CreateContentXmlFile xmlfile,Rs 
	End Function 


	Rem 列表和搜索xml数据
	Private Function WriteListAndSearchDataToXml
		
		Dim sPagesize,TotalPage,CurPage,TotalRec
		sPagesize = m_PageSize * m_CachePageNum

		m_CurPage = CLng(m_CurPage)
		
		If m_CurPage Mod m_CachePageNum = 0 Then 
			CurPage = m_CurPage/m_CachePageNum
		Else
			CurPage = int(clng(m_CurPage)/m_CachePageNum)+1
		End If 

		Dim xmlfile
		xmlfile = getXmlFileName(CurPage)

		Rem 如果xml未过期则直接退出
		If FSOExistsFile(xmlfile) Then
			If Not isXmlCacheExpired(xmlfile,m_CacheTime) Then  Exit Function 
		End If
		Dim rs
		Set Rs = Server.CreateObject("Adodb.Recordset")
		Rs.open m_sql,m_DataConn,1
		TotalRec = rs.recordcount
		rs.pagesize = sPagesize
		If  CurPage>rs.PageCount Then  CurPage = rs.PageCount
		CreateListAndSearchXMLFile xmlfile,TotalRec,Rs,sPagesize
	End Function 



	Rem 私有方法
	Rem 得到文件的最后修改时间
	Private Function FSOGetFileLastModifiedTime(file)
		Dim fso,f,s   
		Set fso=CreateObject("Scripting.FileSystemObject")   
		Set f=fso.GetFile(file)   
		FSOGetFileLastModifiedTime = f.DateLastModified