ASP网页编程之用多种办法制造WEB页面的计数器
SQLServer是基于服务器端的中型的数据库，可以适合大容量数据的应用，在功能上管理上也要比Access要强得多。在处理海量数据的效率，后台开发的灵活性，可扩展性等方面强大。Onewaytodoit:Doyouliketoknowhowmanyusersvisitedyoursite?CreatingaWebcounterisveryeasythingtodo
usingASP.Theonlythingyouhavetodoistouseanapplicationservervariablecalledcount,this
variablewillhavethevaluezerowhenyourapplicationisstartedforthefirsttime,andeverytimeanew
visitorwillcometoyoursitethecountvariablewillbeincremented,theincrementsectionwillbe
writtenintheSession_OnStartintheGlobal.asathroughthreesteps:
¨Locktheapplicationserversonomorethanonevisitorwilltrytoincreaseitatthesametime.
¨Incrementthecountvariablebyone.
¨Unlockthevariable.
Andthat’sallwhatyouhavetodotocreateasimplecounterandhereisthecode.
FirstletusdotheGlobal.asasection:
<SCRIPTLANGUAGE=VBScriptRUNAT=Server>
SubSession_OnStart
LocktheApplicationobject
Application.Lock
Incrementthecount
Application("count")=Application("count")+1
UnlocktheApplicationobject
Application.Unlock
EndSub
</SCRIPT>
Andnowtoshowtheresultyoujustneedtoretrievethecountvariablelikethisinyourwebpage:
<%@language="vbscript"%>
<HTML>
<HEAD>
<TITLE>CounterExample1</TITLE>
</HEAD>
<BODY>
<H1>Youarethevisitornumber<%=Application("count")%></H1>
</BODY>
</HTML>
Anotherwaytodoit:
Okthat’sverynice,butwhatwillhappeniftheapplicationstopsforanyreason?Youwillloseallthe
datastoredintheapplicationvariablesandthatincludesthecountvariable.TosolvethisproblemI
willuseanotherway,youneedtostorethevalueofthecountvariablewithinatextfileordatabase.
FormeIpreferdatabasesoIwilluseanMSaccessdatabasewithatableofonefieldcalledcountand
thefieldcalledcounteroftypeNUMBER.
<%
Declarethevariablesthatwillbeusedwithourcode
DimConnection,RS,ConStr,Counts
Createandopenthedatabaseconnection
SetConnection=Server.Createobject("ADODB.Connection")
ConStr=("DRIVER={MicrosoftAccessDriver(*.mdb)};DBQ="&Server.MapPath("counter.mdb"))
Connection.OpenConStr
Createtherecordsetandretrivethecountervalue
SetRS=Connection.Execute("SELECT*FROMcount")
Increasethecountervaluebyone
Counts=RS("counter")+1
Updatethecountervalueinthedatabase
SetRS=Connection.Execute("UPDATEcountSETcounter="&Counts)
Connection.Close
%>
<HTML>
<HEAD>
<TITLE>CounterExample2</TITLE>
</HEAD>
<BODY>
<H1>Youarethevisitornumber<%=Counts%></H1>
</BODY>
</HTML>
WhataboutActiveusers:
Someguyswantstoknowhowmanyvisitorsarecurrentlyseeingthesite,forthatwewilluseanotherway,
wewillcreateanapplicationvariablecalledactive,andoneachnewsessionwewillincreaseitbyone
andwhenasessionendswewilldecreaseitbyone,andhereisthecode:
TheGlobal.asa:
<SCRIPTLANGUAGE="VBScript"RUNAT="Server">
SubApplication_OnStart
Createthevariablethatwillholdthenumberofactivevisitors
Application("Active")=0
EndSub
SubSession_OnStart
Increasethecounterbyone
Application.Lock
Application("Active")=Application("Active")+1
Application.UnLock
EndSub
SubSession_OnEnd
Decreasethecounter
Application.Lock
Application("Active")=Application("Active")-1
Application.UnLock
EndSub
</SCRIPT>
AndtoshowtheresultsjustcalltheApplicationvariableactiveinyourwebpagejustlikethis:
<%=Application("Active")%>
Ihopeyoucancreateyourowncountersfromnowon.Giveittryandgoodluck.
专业性的服务。有的ASP商提供垂直型的应用服务，针对某一特定行业提供应用服务。 用户端的浏览器不需要提供任何别的支持，这样大提高了用户与服务器之间的交互的速度。 Session:这个存储跟客户端会话过程的数据，默认20分钟失效 它可通过内置的组件实现更强大的功能，如使用A-DO可以轻松地访问数据库。 你可以通过继承已有的对象最大限度保护你以前的投资。并且C#和C++、Java一样提供了完善的调试/纠错体系。 不能只是将它停留在纸上谈兵的程度上。 哪些内置对象是可以跳过的，或者哪些属性和方法是用不到的? 在平时的学习过程中要注意现学现用，注重运用，在掌握了一定的基础知识后，我们可以尝试做一些网页，也许在开始的时候我们可能会遇到很多问题，比如说如何很好的构建基本框架。
页:
[1]