asp.net 2.0中实现异步处理任务.

以下内容是在newsgroups中解决一个朋友的问题而写的demo,留下给自己做个备忘录.
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关于PageAsyncTask在MSDN上的参考
ms-help://MS.VSCC.v90/MS.MSDNQTR.v90.en/fxref_system.web/html/08ffac7a-2c3c-27ee-1445-5284a226be38.htm

说明:此页面中,在Page_Load方法中,同时启动4个较耗时的任务(线程),让它们并行的运行,然后等待他们都运行完毕或超时.

usingSystem;

usingSystem.Diagnostics;

usingSystem.Threading;

usingSystem.Web.Mvc;

usingSystem.Web.UI;

namespacePortal.Views.Home

{

publicpartialclassIndex:ViewPage

{

privatestring_asyncResult;

privateAsyncTaskDelegate_asyncTask;

protectedvoidPage_Load(objectsender,EventArgse)

{

Stopwatchsw=Stopwatch.StartNew();

PageAsyncTasktask1=

newPageAsyncTask(OnTaskBegin,OnTaskEnd,OnTaskTimeout,"A1",true);

PageAsyncTasktask2=

newPageAsyncTask(OnTaskBegin,OnTaskEnd,OnTaskTimeout,"B2",true);

PageAsyncTasktask3=

newPageAsyncTask(OnTaskBegin,OnTaskEnd,OnTaskTimeout,"C3",true);

PageAsyncTasktask4=

newPageAsyncTask(OnTaskBegin,OnTaskEnd,OnTaskTimeout,"D4",true);

RegisterAsyncTask(task1);

RegisterAsyncTask(task2);

RegisterAsyncTask(task3);

RegisterAsyncTask(task4);

//Bydefault,anasynchronoustaskwilltimeoutifithasnotcompleted

//within45seconds.

AsyncTimeout=TimeSpan.FromSeconds(60);

ExecuteRegisteredAsyncTasks();

sw.Stop();

//now,wecangetthetaskresulthere.

Response.Write(_asyncResult);

Response.Write(sw.Elapsed.TotalSeconds);

}

privateIAsyncResultOnTaskBegin(objectsender,

EventArgse,

AsyncCallbackcallback,

objectdata)

{

_asyncTask=delegate(stringtext)

{

//TODO:addyourasynctaskhere.

stringresponse=

string.Format("AsyncTask{0}startedat:{1}.",text,DateTime.Now);

Thread.Sleep(TimeSpan.FromSeconds(10));

response+=

string.Format("AsyncTask{0}endedat:{1}.\n",text,DateTime.Now);

returnresponse;

};

IAsyncResultresult=_asyncTask.BeginInvoke((string)data,callback,data);

returnresult;

}

privatevoidOnTaskEnd(IAsyncResultar)

{

_asyncResult+=_asyncTask.EndInvoke(ar);

}

privatevoidOnTaskTimeout(IAsyncResultar)

{

_asyncResult=string.Format("AsyncTask{0}istimeout.",ar.AsyncState);

}

#regionNestedtype:AsyncTaskDelegate

protecteddelegatestringAsyncTaskDelegate(stringtext);

#endregion

}

}

.csharpcode,.csharpcodepre
{
font-size:small;
color:black;
font-family:consolas,"CourierNew",courier,monospace;
background-color:#ffffff;
/*white-space:pre;*/
}
.csharpcodepre{margin:0em;}
.csharpcode.rem{color:#008000;}
.csharpcode.kwrd{color:#0000ff;}
.csharpcode.str{color:#006080;}
.csharpcode.op{color:#0000c0;}
.csharpcode.preproc{color:#cc6633;}
.csharpcode.asp{background-color:#ffff00;}
.csharpcode.html{color:#800000;}
.csharpcode.attr{color:#ff0000;}
.csharpcode.alt
{
background-color:#f4f4f4;
width:100%;
margin:0em;
}
.csharpcode.lnum{color:#606060;}

.csharpcode,.csharpcodepre
{
font-size:small;
color:black;
font-family:consolas,"CourierNew",courier,monospace;
background-color:#ffffff;
/*white-space:pre;*/
}
.csharpcodepre{margin:0em;}
.csharpcode.rem{color:#008000;}
.csharpcode.kwrd{color:#0000ff;}
.csharpcode.str{color:#006080;}
.csharpcode.op{color:#0000c0;}
.csharpcode.preproc{color:#cc6633;}
.csharpcode.asp{background-color:#ffff00;}
.csharpcode.html{color:#800000;}
.csharpcode.attr{color:#ff0000;}
.csharpcode.alt
{
background-color:#f4f4f4;
width:100%;
margin:0em;
}
.csharpcode.lnum{color:#606060;}

reference:http://msdn.microsoft.com/en-us/library/system.web.ui.pageasynctask(zh-cn).aspx