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标题: ASP.NET编程：一个完成自界说event的文章。。。我还没... [打印本页]

作者: 愤怒的大鸟 时间: 2015-1-16 22:50
标题: ASP.NET编程：一个完成自界说event的文章。。。我还没...
我认为，可以通过更加简单的首次编译，而增加第二次编译的负担，来提高java的运行效率。只是将java源代码进行简单的等价转换，而不假设编译成某种虚拟机器的目标格式，而由本地编译器针对性的二次编译。ThelatestofferingfromMicrosofttosupportsoftwaredevelopmentisthe.NETFramework.InsidethisvastFrameworkistheASP.NET.TheASP.NETfacilitatestheapplicationdevelopmentcommunityingeneratinghighperformanceWebbasedapplicationsthatcanbedatarichandworkinaheterogeneousenvironment.

Inthisdiscussionwewillexaminethestepstocreateacustomeventthatwillalerttheuserorprocessthateventhastakenplaceunderaspecifiedcondition.Tounderstandhowtosetupthecodestructuretoraiseandhandleevents,anoverviewoftheeventarchitectureisneeded.

EventArchitecture

Belowareanumberofkeypointsthatencompassthe.NetFrameworkeventmodel.

-Eventstakingplaceinthe.NETFrameworkarebaseduponthedelegatemodel.
-Thedelegateclassisthemechanismthatallowstheeventsendertocommunicatewiththeeventhandler.
-Aneventsendercanbroadcastaneventtoanumberofeventhandlers.
-Aneventhandlermustberegisteredwithaneventsender.

Thefundamentaldefinitionofaneventis:Aneventisamessagethathasbeensentbyanobjectduetosomeoccurrenceofanactionwithintheworkflowoftheapplication.Thisactioncouldbeabuttonthathasbeenclickedorspecifiedtimeoutparametervaluehasbeenreached.Thisactiontriggerstheeventandthesubsequentmethodthathandlestheeventisinitiatedandtheeventishandled.

Inthe.NETframework,thesendingobjectdoesnotknowwhatmethodwillhandletheevent.Therefore,anagentmustbeutilizedtohandlethecommunication.Thisagentisthedelegateclassthatholdsareferencetothemethodthathandlestheevent.Thedelegateclasshasanintrinsicsignatureandcanonlyholdreferencestomethodsthatobtainthesamesignature.Youcanequivocatethedelegateclasstoatype-safepointertoacallback.Theeventdelegatehastwoparameters;thesearethesendingobjectandthereturneddata.BelowinListing1isgenericdeclarationoftheeventdelegateclass.

Listing1

PublicdelegatevoidEventHandler(objectSender,EventArgse);

Inordertoinitiateandhandlecustomevents,eventfunctionalityneedstobeprovided.Thefundamentalstructureislistedasfollows:

-Aclasstoholdtheeventdata.ThismustbeinheritedfromSystem.EventArgs.
-Adelegatefortheevent.
-Aclassthatraisestheevent.
-Aclasswithamethodthathandlestheevent.

Nowthatwehavediscussedthefundamentalsofeventhandling,weneedasimpleapplicationtodepicttheeventfunctionality.

CustomEventsApplication

TheCustomEventsApplicationiscomprisedofasimpleWebFormthatdisplaystheeventdatamessage.ThisisshowninFigure1.

Figure1

Inordertoinitiatesomeactionthatshowsthefunctionalityofeventhandling,aloopiscreatedtocounttosomenumberandstop.Duringthiscount,aspecificvalueisinterrogatedwithintheloop.Whenthespecifiedvalueisequaltotheloopvalue,theeventisfired.Inthiscasethevalueis400000.Thelooprunsfrom1to500000.Whenthevalue400000isreachedtheOnMessagemethodiscalledandtheeventisraised.Note:TheInitEvent()methodiscalledfromPage_Load()methodwhenthepageisrequested.TheInitEvent()methodisdepictedinListing2.

Listing2

privatevoidInitEvent()
{
MessagingHandlermh=newMessagingHandler();
MessageEventme=newMessageEvent();
me.Message+=newMessageHandler(mh.GetMessageData);

for(inti=1;i<=500000;i++)
{
if(i==400000)
{
MessageEventArgse=newMessageEventArgs();
me.OnMessage(e);
lblMessage.Text=mh.EventMessage;
}
}
}

AsyoucanseethisiscertainlyoverkilltodisplayalineoftextinalabelfieldonaWebpage.However,itisusefultoexaminetheworkflowofaneventthatiscapturedandhandledinthe.NETFramework.InordertomakesenseofthecodefragmentinListing2,weneedtoexaminetheclassesthatcomprisetheeventstructure.BelowinListing3showstherespectivecomponentsthatwillraiseandhandletheeventasittranspires.

Listing3

publicclassMessageEventArgs:EventArgs
{
publicstringMessageText
{
get
{
return("Therehasbeen400000valuesprocessed.");
}
}
}

publicdelegatevoidMessageHandler(objectsender,MessageEventArgse);

publicclassMessageEvent
{
publiceventMessageHandlerMessage;

publicvoidOnMessage(MessageEventArgse)
{
if(Message!=null)
{
Message(this,e);
}
}
}

publicclassMessagingHandler
{
privatestringstrMessage;
publicstringEventMessage
{
get
{
returnstrMessage;
}
set
{
strMessage=value;
}
}

publicvoidGetMessageData(objectsender,MessageEventArgse)
{
stringstrMessage=e.MessageText;
EventMessage=strMessage;
}
}

TheclassMessageEventArgswillsupplythedataforevent.NoticethatitisinheritedfromEventArgs.AsyoucanseeMessageTextisapropertyoftheclassandagetstatementisutilizedtoreturnthedatastring.ThedelegateinthiscaseistheMessageHandler.IthasthesenderobjectandtheMessageEventArgsforthedatainitsargumentlist.MovingontotheclassMessageEvent.ThisclasswillraisetheeventwiththeOnMessage()methodbyinvokingthedelegates.TheMessagingHandlerclasswillextracttheeventmessagefromtheMessageEventArgsandpopulatetheEventMessagepropertysothemessagecanbedisplayedontheWebpage.

Insummarization,wehaveaclassthatsuppliesthedata,adelegatetoprovidethecommunication,aclasstoraisetheevent,andaclasstohandletheevent.Thebasicworkflowisasfollows:

-TheInitEvent()isinitiatedfromthePage_Load()methodwhenthepageisrequested.
-MessagingHandlermh=newMessagingHandler()instantiatestheMessagingHandlerclass-EventReceiver.
-MessageEventme=newMessageEvent()instantiatestheMessageEventclass-EventSender.
-me.Message+=newMessageHandler(mh.GetMessageData)registerstheeventhandlerwiththeeventsourcesothattheMessagingHandlerinstancecanreceivealarmevents.The+=assignmentoperatoraddsthedelegatetothelistofdelegatesthatareregisteredwiththeMessageevent.
-Whenthespecifiedvalueisreached,MessageEventArgse=newMessageEventArgs()isinstantiatedandtheOnMessage()iscalledtoraisetheevent.
-TheOnMessage()methodinvokesthedelegatewhichcallstheGetMessageData()methodtohandletheevent.
-TheGetMessageData()methodobtainsthemessagetextfromtheMessageEventArgsandpopulatestheEventMessagepropertywiththestringdata.
-ThelabelfieldispopulatedwiththeEventMessagestringpropertyvalueanddisplayedontheWebpage.

Runthisexample

[runit]

Conclusion

SinceWebbasedapplicationsaredisconnectedinnatureandthehandlingofeventsaretypicallyserver-sidetheeventmessageisdisplayedaftertheentirecodesequencehastranspired.Thisparadigmisnotconduciveforasynchronousprocessingduetothefire-and-forgetprocessing.However,theycanbeusefulifyouaredoingheavyserver-sideprocessingandvalidationbeforerenderingthepage.

The.NETFrameworkisprovidingtheapplicationdeveloperagreatdealofoptionstogeneratemeaningfulsolutionstotheenterprise,beitWebbasedapplications,WindowsClientbasedapplications,orServerbasedSer
[img=1border=0style=,1src=]http://www.ckuyun.com/[/img]

感觉很多控件都必须自己去写代码；用了WebMatrix感觉也不是很好，毕竟没有很强的WYSIWYG效果。现在就不知道如何是好了。

作者: 小魔女 时间: 2015-1-18 15:43
ASP.NET:ASP.net是Microsoft.net的一部分，作为战略产品，不仅仅是ActiveServerPage(ASP)的下一个版本；它还提供了一个统一的Web开发模型，其中包括开发人员生成企业级Web应用程序所需的各种服务。ASP.NET的语法在很大程度上与ASP兼容，同时它还提供一种新的编程模型和结构，可生成伸缩性和稳定性更好的应用程序，并提供更好的安全保护。

作者: 再现理想 时间: 2015-1-22 07:52
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。

作者: 爱飞 时间: 2015-1-30 23:54
在一个项目中谁敢保证每天几千万甚至几亿条的数据不丢失?谁敢保证应用的高可靠性？有可以借签的项目吗？

作者: 谁可相欹 时间: 2015-2-6 17:17
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。

作者: 仓酷云 时间: 2015-2-17 14:53
同时也感谢博客园给我们这个平台，也感谢博客园的编辑们做成专题引来这么多高人指点。

作者: 第二个灵魂 时间: 2015-3-5 20:24
asp.net空间的支持有:ASP.NET1.1/虚拟目录/MicrosoftFrontPage2000扩展/CDONTS,同时他的网站上也提供了Asp.net的使用详解和程序源代码，相信对使用ASP.NET编程的程序员来说会非常有用哦!

作者: 飘灵儿 时间: 2015-3-12 13:38
碰到复杂点的问题都不知道能不能解决，现在有点实力的公司都选择自已在开源的基础上做开发。但没听说过有人在IIS上做改进的,windows、sqlserver集群方面的应用也很少见。

作者: 蒙在股里 时间: 2015-3-19 22:34
PHP的源代码完全公开，在OpenSource意识抬头的今天，它更是这方面的中流砥柱。不断地有新的函数库加入，以及不停地更新，使得PHP无论在UNIX或是Win32的平台上都可以有更多新的功能。它提供丰富的函数，使得在程式设计方面有着更好的资源。目前PHP的最新版本为4.1.1，它可以在Win32以及UNIX/Linux等几乎所有的平台上良好工作。PHP在4.0版后使用了全新的Zend引擎，其在最佳化之后的效率，比较传统CGI或者ASP等技术有了更好的表现。

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