实践xml缓存技术构建高性能web站点

2008-09-22 17:18:22  来源:网页教学网 

WebjxCom提示: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

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
  Set f = Nothing
  Set fso = Nothing
 End Function

 Rem 判断xml缓存是否到期
 Private Function isXmlCacheExpired(file,seconds)
  Dim filelasttime
  filelasttime = FSOGetFileLastModifiedTime(file)
  If DateAdd("s",seconds,filelasttime) < Now Then
   isXmlCacheExpired = True
  Else
   isXmlCacheExpired = False
  End If
 End Function
 Rem 文件是否存在
 Private Function FSOExistsFile(file)
  Dim fso
  Set fso = Server.CreateObject("Scripting.FileSystemObject")
  If fso.FileExists(file) Then
   FSOExistsFile = true
  Else
   FSOExistsFile = false
  End If
  Set fso = nothing
 End Function
 
 Rem 生成详细数据的xml
 Private Function CreateContentXmlFile(xmlfile,Rs)
  Dim xmlcontent
  xmlcontent = "<?xml version=""1.0"" encoding=""gb2312""?>" & vbnewline
  xmlcontent = xmlcontent & "<root>" & vbnewline
 
  Dim field
  For Each field In rs.Fields
   xmlcontent = xmlcontent & "<"&field.name&">"
   Dim value
   value = field.value
   If TypeName(value) = "String" Then
    xmlcontent = xmlcontent & "<![CDATA[" & Trim(value) & "]]>"
   Else
    xmlcontent = xmlcontent &  Trim(value)
   End If
   xmlcontent = xmlcontent & "</"&field.name&">" & vbnewline
  Next
  rs.close
  Set rs = Nothing
  xmlcontent = xmlcontent & "</root>" & vbnewline
 
  Dim folderpath
  folderpath = Trim(left(xmlfile,InstrRev(xmlfile,"\")-1))
  Call CreateDIR(folderpath&"") '创建文件夹
  WriteStringToXMLFile xmlfile,xmlcontent
 End Function

 Rem 生成列表的xml
 Private Function CreateListAndSearchXMLFile(xmlfile,TotalRec,Rs,sPagesize)
  Dim xmlcontent
  xmlcontent = ""
  xmlcontent = xmlcontent & "<?xml version=""1.0"" encoding=""gb2312""?>" & vbnewline
  xmlcontent = xmlcontent & " <root>" & vbnewline
  xmlcontent = xmlcontent & "  <totalrec>" & TotalRec & "</totalrec>" & vbnewline
  Dim k
  k = 0
  Dim field
  While Not rs.eof and k<sPagesize
   xmlcontent = xmlcontent & "  <item "
   For Each field In rs.Fields
    xmlcontent = xmlcontent & field.name & "=""" & XMLStringEnCode(field.value) & """ "
   Next
   xmlcontent = xmlcontent &  "></item>" & vbnewline
   rs.movenext
   k=k+1
  Wend
  rs.close
  Set rs = Nothing
  xmlcontent = xmlcontent & " </root>" & vbnewline
  Dim folderpath
  folderpath = Trim(left(xmlfile,InstrRev(xmlfile,"\")-1))
  Call CreateDIR(folderpath&"") '创建文件夹
  WriteStringToXMLFile xmlfile,xmlcontent
 End Function
 Rem xml转义字符
 Private Function XMLStringEnCode(str)
  If str&"" = "" Then XMLStringEnCode="":Exit Function
  str = Replace(str,"<","&lt;")
  str = Replace(str,">","&gt;")
  str = Replace(str,"'","&apos;")
  str = Replace(str,"""","&quot;")
  str = Replace(str,"&","&amp;")
  XMLStringEnCode = str
 End Function
 Rem 写文件
 Private Sub WriteStringToXMLFile(filename,str)
  'On Error Resume Next
  Dim fs,ts
  Set fs= createobject("scripting.filesystemobject")
  If Not IsObject(fs) Then Exit Sub  
  Set ts=fs.OpenTextFile(filename,2,True)
  ts.writeline(str)
  ts.close
  Set ts=Nothing
  Set fs=Nothing
 End Sub

 Rem 创建文件夹
 Private function CreateDIR(byval LocalPath)
  On  Error  Resume  Next
  Dim i,FileObject,patharr,path_level,pathtmp,cpath
  LocalPath = Replace(LocalPath,"\","/")
  Set  FileObject = server.createobject("Scripting.FileSystemObject")
  patharr = Split(LocalPath,"/")
  path_level = UBound (patharr)
  For  i = 0 To  path_level
   If  i=0 Then 
    pathtmp=patharr(0) & "/"
   Else 
    pathtmp = pathtmp & patharr(i) & "/"
   End If
   cpath = left(pathtmp,len(pathtmp)-1)
   If  Not  FileObject.FolderExists(cpath) Then
    'Response.write cpath
    FileObject.CreateFolder cpath
   End  If
  Next
  Set  FileObject = Nothing
  If  err.number<>0 Then
   CreateDIR = False
   err.Clear
  Else
   CreateDIR = True
  End  If
 End  Function
End Class
%>

此类包含两种缓存方式:一种是基于列表方式的,如按照某个类别显示信息、搜索某个关键词进行显示;另外一种是详细页面的缓存,如显示具体的某篇文章。
此类与具体的业务逻辑无关,只负责xml数据的读取和存储,判断是否缓存过期决定是否需要更新缓存。按照三层构架模式的话,它处于数据访问层。

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