ASP网站制作之用ASP创建一个复杂的搜刮引擎
只要你想学,就没什么优缺点,上面那位大哥已经把网上的评论说了,但我认为想学哪个都一样,不然它就不可能在当今时代数字艺术方面存活到今天搜刮引擎ByScottMitchellAsawebsitegrows,findingcontentonthesitebecomesincreasinglydifficult.Tocombatthedifficulty
offindingrelevantinformationonalargesite,manydevelopersturntowritingasearchenginefortheir
site.ThisarticlediscusseshowtoimplementsuchasystemusingActiveServerPagesandSQLServer.
Therearetwo"types"ofsearchengines.Bothtakeasearchstringfromtheusertobegin,butwhat,
exactly,theysearchdiffers.Acompletelydynamicsearchengineforacompletelydynamicwebsitewill
hitadatabasetablewhichtiesanarticleURLtothearticlesdescription.Thedatabasecanthencompare
theuserssearchrequesttothedescriptionsoftheavailablearticlesandreturntherelevantURLs.
Anotherapproachistodoanactualtextsearchthrougheachofthefiles.Forexample,saythattheuser
searchedfor"Microsoft."YoursearchenginewouldthenlookthroughallofyourHTMLfilesandreturnthe
URLsofthosewhichhadtheword"Microsoft"somewhereinthedocument.Suchasystemisusedforthisweb
sitessearchengine.Inmyopinion,itismucheasiertowritesuchasystemdescribedinPerl(which
thissystemiswrittenin),thaninActiveServerPages;however,itisquitepossibletowriteatext-
findingsearchsysteminASP.
InthisarticleIplantoimplementtheformersearchengine,thedynamicsearchengine.Forthisexample
IwillmakeatablecalledArticleURL,whichwillhavethefollowingdefinition:
ArticleURL
ArticleURLIDintPK
URLvarchar(255)
Titlevarchar(100)
Descriptionvarchar(255)
Nowthatwevegotourtabledefinition,letslookathowourwebvisitorswillentertheirqueries.
SearchQuerying
Asearchengineisratheruselessunlessqueriescanbemade,andtheresultsarereturned.Letsexamine
howwewillcodethefirstneededpart,theusersearchrequests.AllwewillneedisasimpleHTMLFORM
whichtakesinputfromtheuserandpassesitontoanASPpage.Hereisanexampleofafilewellcall
SearchStart.htm:
<HTML>
<BODY>
<FORMMETHOD=POSTACTION="Search.asp&ID=0">
>Searchfor:<INPUTTYPE=TEXTNAME="txtSearchString"SIZE="50">
<P>
<INPUTTYPE=SUBMIT>
</FORM>
</BODY>
</HTML>
This,ofcourse,isnotaprettyHTMLpage,butitsfunctionalityisthere.Therearemanythingswhich
couldbedonetoenhancethispage.ItisrecommendedthatJavaScriptfunctionsbepresenttomakesure
theuserissearchingsomething(i.e.notjustclickingSubmitwhenthereisnosearchstring).
NowthatwehavetheQuery,weneedtolookatthesecondphaseofanysearchengine:retrievingthedata
andpresentingittotheuser.Hereiswheretherealfunbegins!
RetrievingtheDataandPresentingIt:
OurASPpageSearch.aspmustdoafewsteps.First,itmustparsetheFORMvariabletxtSearchString.Right
now,IamassumingthateachwordinthetxtSearchStringseparatedbyaspacewillbeANDedtogether.You
canalterthis(haveitORed),or,tomakeitmoreprofessional,youcangivetheusertheoptionofwhich
booleantoputinbetweeneachspacedword.
Next,Search.aspwillneedtohitthedatabasetableArticleURLandreturnthedatainauser-friendly
fashion.Also,wewillwanttodisplaytheresultsonly10recordsatatime,sologicwillneedtobe
implementedtohandlethisaswell.Letslookatsomecode.
<%
ConnecttoDatabase
DimConn
SetConn=Server.CreateObject("ADODB.Connection")
Conn.OpenApplication("MyConnectString")
Settheseuptoyourpreference
DefaultBoolean="AND"
RecordsPerPage=10
Getourformvariable
DimstrSearch
strSearch=Request.form("txtSearchString")
GetourcurrentID.ThisletsusknowwhereweareDimID
ID=Request.QueryString("ID")
SetupourSQLStatement
DimstrSQL,tmpSQL
strSQL="SELECT*FROMArticleURLWHERE"
tmpSQL="(DescriptionLIKE"
OK,weneedtoparseourstringhere
DimPos
Pos=1
WhilePos>0
Pos=InStr(1,strSearch,"")
IfPos=0Then
Wehavehittheend
tmpSQL=tmpSQL&a</p>Access是一种桌面数据库，只适合数据量少的应用，在处理少量数据和单机访问的数据库时是很好的，效率也很高。但是它的同时访问客户端不能多于4个。access数据库有一定的极限，如果数据达到100M左右，很容易造成服务器iis假死，或者消耗掉服务器的内存导致服务器崩溃。 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? ASP的语言不仅仅只是命令格式差不多，而是包含在<%%>之内的命令完全就是VB语法。虽然ASP也是做为单独的一个技术来提出的，但他就是完全继承了VB所有的功能。 弱类型造成潜在的出错可能：尽管弱数据类型的编程语言使用起来回方便一些，但相对于它所造成的出错几率是远远得不偿失的。 Application:这个存储服务端的数据，如果不清除，会直到web应用程序结束才清除(例如重启站点) 以上是语言本身的弱点，在功能方面ASP同样存在问题，第一是功能太弱，一些底层操作只能通过组件来完成，在这点上是远远比不上PHP/JSP，其次就是缺乏完善的纠错/调试功能，这点上ASP/PHP/JSP差不多。 下载一个源代码，然后再下载一个VBScript帮助，在源代码中遇到不认识的函数或是其他什么程序，都可以查帮助进行解决，这样学习效率很高。 那么，ASP.Net有哪些改进呢？ 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?
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