实践xml缓存技术构建高性能web站点

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

'http://www.knowsky.com/article.asp?typeid=2

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

'http://www.devdao.com/

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

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

num = num + 1

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

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

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) & """ "

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,"<","<")

str = Replace(str,">",">")

str = Replace(str,"'","'")

str = Replace(str,"""",""")

str = Replace(str,"&","&")

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

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。

调用这个类的代码：

Business.asp

Rem xml数据缓存类业务逻辑层代码

'--------------------------------------------------

'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

'--------------------------------------------------

Rem 根据classid取列表数据

Function GetListarr(classid,curpage,PageSize,CachePageNum,ByRef RecordCount)

openConn

Dim sql

sql = "select thmid,thmname,picfileurl,win_theme.adddate from win_theme where win_theme.ClassID="&classid&" order by thmid desc"

Dim cache

Set cache = new XmlCacheCls

cache.PageSize = PageSize '每页N条记录

cache.CachePageNum = CachePageNum '一个xml文件缓存M页的数据量

cache.XmlFile = Server.Mappath("xmlcache/classxml/list_"&classid&".xml")

cache.Sql = sql

cache.CurPage = curpage

cache.CacheType = 1

Set cache.Conn = conn

cache.ReadData

Dim SqlArr

SQLArr = cache.SQLArr

RecordCount = cache.RecordCount

Set cache = Nothing

GetListarr = SqlArr

End Function

Rem 根据classid生成xml缓存

Function CreateListxml(classid,curpage,PageSize,CachePageNum,CacheTime)

Dim sql

sql = "select thmid,thmname,picfileurl,win_theme.adddate from win_theme where win_theme.ClassID="&classid&" order by thmid desc"

Dim cache

Set cache = new XmlCacheCls

cache.CacheTime = CacheTime '缓存时间

cache.PageSize = PageSize '每页N条记录

cache.CachePageNum = CachePageNum '一个xml文件缓存M页的数据量

cache.XmlFile = Server.Mappath("xmlcache/classxml/list_"&classid&".xml")

cache.Sql = sql

cache.CurPage = curpage

cache.CacheType = 1

Set cache.Conn = conn

cache.WriteDataToXml

Set cache = Nothing

End Function

Rem 根据keyword取列表数据

Function GetSearcharr(keyword,curpage,PageSize,CachePageNum,ByRef RecordCount)

openConn

Dim sql

Dim sqlkey

sqlkey = Replace(keyword,"'","")

sql = "select thmid,thmname,picfileurl,win_theme.adddate from win_theme where ThmName like '%"&sqlkey&"%' or ThmRange like '%"&sqlkey&"%' or ThmInstro like '%"&sqlkey&"%' order by thmid desc"

Dim cache

Set cache = new XmlCacheCls

cache.PageSize = PageSize '每页N条记录

cache.CachePageNum = CachePageNum '一个xml文件缓存M页的数据量

cache.XmlFile = Server.Mappath("xmlcache/searchxml/list_"&Server.URlEncode(Replace(keyword,"'",""))&".xml")

cache.Sql = sql

cache.CurPage = curpage

cache.CacheType = 1

Set cache.Conn = conn

cache.ReadData

Dim SqlArr

SQLArr = cache.SQLArr

RecordCount = cache.RecordCount

Set cache = Nothing

GetSearcharr = SqlArr

End Function

Rem 根据keyword生成xml缓存

Function CreateSearchxml(keyword,curpage,PageSize,CachePageNum,CacheTime)

Dim sql

Dim sqlkey

sqlkey = Replace(keyword,"'","")

sql = "select thmid,thmname,picfileurl,win_theme.adddate from win_theme where ThmName like '%"&sqlkey&"%' or ThmRange like '%"&sqlkey&"%' or ThmInstro like '%"&sqlkey&"%' order by thmid desc"

Dim cache

Set cache = new XmlCacheCls

cache.CacheTime = CacheTime '缓存时间

cache.PageSize = PageSize '每页N条记录

cache.CachePageNum = CachePageNum '一个xml文件缓存M页的数据量

cache.XmlFile = Server.Mappath("xmlcache/searchxml/list_"&Server.URlEncode(Replace(keyword,"'",""))&".xml")

cache.Sql = sql

cache.CurPage = curpage

cache.CacheType = 1

Set cache.Conn = conn

cache.WriteDataToXml

Set cache = Nothing

End Function

Rem 根据classid取列表数据

Function GetDetailarr(thmid)

openConn

Dim sql

sql = "select a.thmid,a.thmname,a.classid,b.classname,a.picfileurl,a.thmver,a.thmsize,a.thminstro,a.thmrange,a.thmfileurl,a.adddate from win_theme a,Win_Classify b where a.classid=b.classid and a.thmid="&thmid&""

Dim thmidmod

thmidmod = thmid Mod 100

Dim cache

Set cache = new XmlCacheCls

cache.XmlFile = Server.Mappath("xmlcache/detailxml/"&thmidmod&"/"&thmid&".xml")

cache.Sql = sql

cache.CacheType = 2

Set cache.Conn = conn

cache.ReadData

Dim SqlArr

SQLArr = cache.SQLArr

Set cache = Nothing

GetDetailarr = SqlArr

End Function

Rem 根据keyword生成xml缓存

Function CreateDetailxml(thmid,CacheTime)

Dim sql

Dim thmidmod

thmidmod = thmid Mod 100

Dim cache

Set cache = new XmlCacheCls

cache.CacheTime = CacheTime '缓存时间

cache.XmlFile = Server.Mappath("xmlcache/detailxml/"&thmidmod&"/"&thmid&".xml")

cache.Sql = sql

cache.CacheType = 2

Set cache.Conn = conn

cache.WriteDataToXml

Set cache = Nothing

End Function

Rem 检测动态数组是否已分配

Function ismalloc(a)

On Error Resume Next

Dim i

i = UBound(a)

If Err Then

ismalloc = False

Else

ismalloc = True

End If

End Function

Function showData(SQLArr)

If Not ismalloc(SQLArr) Then Exit Function

Dim i,k

Dim num

num = 0

i = UBound(SQLArr,1)

k = UBound(SQLArr,2)

Dim m,n

For m = 0 To k

num = num+1

<li>

<a title="<%=SQLArr(1,m)%>" href="detail.asp?id=<%=SQLArr(0,m)%>" target="_blank">

<img height="140" alt="<%=SQLArr(1,m)%>" src="http://www.shouji138.com<%=SQLArr(2,m)%>" width="107" border="0"></a>

</li>

<a title="<%=SQLArr(1,m)%>" href="detail.asp?id=<%=SQLArr(0,m)%>" target="_blank">

<%=walkgottopic(Trim(SQLArr(1,m)),18)%></a>

</li>

</ul>

End Function

这个文件是业务逻辑层代码，负责根据不同的业务逻辑来实现xml数据的读取和写入，并提供接口方法给web表现层调用。

具体的调用代码：

list.asp

只显示相关代码。

。。。。。。

Dim classid

classid = Request("classid")

If classid = "" Or (Not IsNumeric(classid)) Then Response.write "参数错误！":Response.End()

classid = CLng(classid)

Dim sPagesize,TotalPage,CurPage,TotalRec,CachePageNum

sPagesize = 20

CachePageNum = 10

CurPage = Trim(Request("page"))

IF CurPage="" Or (Not IsNumeric(CurPage)) Then

CurPage=1

Else

CurPage=Clng(CurPage)

End IF

Dim myarr

myarr = GetListarr(classid,CurPage,sPagesize,CachePageNum,TotalRec)

'总页数

TotalPage = int(clng(TotalRec)/sPagesize*-1)*-1

If Clng(TotalRec)>0 Then

showData myarr

End If

................

最后在页面最底部调用一个asp的script语句来更新xml缓存。

setcache.asp