ASP.NET Postback的Web Page生命周期-51CTO.COM

说道ASP.NET Postback，就得说Web Page生命周期，但是Web Page生命周期却不是三言两语就能够说得清楚的，所以在这里单纯站的编程的角度，撇开Web Page生命周期浅谈Postback。

我们知道，无论是ASP.NET1.x,2.0，甚至是以后的版本，ASP.NET最终Render到Client端通过浏览器浏览的都是一样：一个单纯的HTML。Client通过Submit Form的方式将填入Form的数据提交给Server进行处理。我们现在来看看ASP.NET Postback程序处理的过程。

首先我们通过一个Sample来看ASP.NET如何处理一个通过Click一个Button引起的Postback。下面是Web Page的HTML：

<%@PageLanguage="C#"AutoEventWireup="true"CodeFile="Default.
aspx.cs"Inherits="_Default"%> 
<!DOCTYPEhtmlPUBLIC"-//W3C//DTDXHTML1.0Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<htmlxmlnshtmlxmlns="http://www.w3.org/1999/xhtml"> 
<headrunatheadrunat="server"> 
<title>TestPage</title> 
</head> 
<body> 
<formidformid="form1"runat="server"> 
<div> 
<asp:Labelrunatasp:Labelrunat="server"ID="LabelMessage"ForeColor="red"></asp:Label> 
</div> 
<div> 
<asp:Buttonrunatasp:Buttonrunat="server"ID="Button1"Text="Button1"OnClick=
"Button1_Click"OnCommand="Button_Command"CommandArgument="Button1"/> 
<asp:Buttonrunatasp:Buttonrunat="server"ID="Button2"Text="Button2"OnClick=
"Button2_Click"OnCommand="Button_Command"CommandArgument="Button2"UseSubmitBehavior="false"/> 
<asp:Buttonrunatasp:Buttonrunat="server"ID="Button3"Text="Button3"OnClick=
"Button3_Click"OnCommand="Button_Command"CommandArgument="Button3"UseSubmitBehavior="false"/> 
</div> 
</form> 
</body> 
</html>

很简单，定义了3个Button，分别注册了他们的两个Event：Click和Command。3个Button的Command Event Hander是一样的：Button_Command，通过指定的CommandArgument来让Event Handler判断到底是哪个Button触发了Command Event。

下面是Code Behind：

usingSystem;  
usingSystem.Data;  
usingSystem.Configuration;  
usingSystem.Web;  
usingSystem.Web.Security;  
usingSystem.Web.UI;  
usingSystem.Web.UI.WebControls;  
usingSystem.Web.UI.WebControls.WebParts;  
usingSystem.Web.UI.HtmlControls;  
 
publicpartialclass_Default:System.Web.UI.Page  
{  
 
protectedvoidPage_Load(objectsender,EventArgse)  
{  
 
}  
protectedvoidButton1_Click(objectsender,EventArgse)  
{  
stringstringmessage=string.Format("The{0}eventof{1}isfired","Click","Button1");  
this.LabelMessage.Text=message;  
}  
protectedvoidButton2_Click(objectsender,EventArgse)  
{  
stringstringmessage=string.Format("The{0}eventof{1}isfired","Click","Button2");  
this.LabelMessage.Text=message;  
}  
protectedvoidButton3_Click(objectsender,EventArgse)  
{  
stringstringmessage=string.Format("The{0}eventof{1}isfired","Click","Button3");  
this.LabelMessage.Text=message;  
}  
 
protectedvoidButton_Command(objectsender,CommandEventArgse)  
{  
stringstringmessage=string.Format("The{0}eventof{1}isfired",
"Command",e.CommandArgument);  
this.LabelMessage.Text+=";"+message;  
}  
}

以上介绍ASP.NET Postback的Web Page生命周期.

【编辑推荐】