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ASP.NET Postback的Web Page生命周期

　　本文标签：Web Page生命周期 ASP.NET Postback

　　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：

  1. <%@PageLanguage="C#"AutoEventWireup="true"CodeFile="Default.
    aspx.cs"    Inherits="_Default"%> 
  2. "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
  3. <htmlxmlnshtmlxmlns="http://www.w3.org/1999/xhtml"> 
  4. <headrunatheadrunat="server"> 
  5. <title>TestPagetitle> 
  6. head> 
  7. <body> 
  8. <formidformid="form1"runat="server"> 
  9. <div> 
  10. <asp:Labelrunatasp:Labelrunat="server"ID="LabelMessage"ForeColor="red">asp:Label> 
  11. div> 
  12. <div> 
  13. <asp:Buttonrunatasp:Buttonrunat="server"ID="Button1"Text="Button1"OnClick=
    "Button1_Click"    OnCommand="Button_Command"CommandArgument="Button1"/> 
  14. <asp:Buttonrunatasp:Buttonrunat="server"ID="Button2"Text="Button2"OnClick=
    "Button2_Click"    OnCommand="Button_Command"CommandArgument="Button2"UseSubmitBehavior="false"/> 
  15. <asp:Buttonrunatasp:Buttonrunat="server"ID="Button3"Text="Button3"OnClick=
    "Button3_Click"    OnCommand="Button_Command"CommandArgument="Button3"UseSubmitBehavior="false"/> 
  16. div> 
  17. form> 
  18. body> 
  19. 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：

  1. usingSystem;  
  2. usingSystem.Data;  
  3. usingSystem.Configuration;  
  4. usingSystem.Web;  
  5. usingSystem.Web.Security;  
  6. usingSystem.Web.UI;  
  7. usingSystem.Web.UI.WebControls;  
  8. usingSystem.Web.UI.WebControls.WebParts;  
  9. usingSystem.Web.UI.HtmlControls;  
  10.  
  11. publicpartialclass_Default:System.Web.UI.Page  
  12. {  
  13.  
  14. protectedvoidPage_Load(objectsender,EventArgse)  
  15. {  
  16.  
  17. }  
  18. protectedvoidButton1_Click(objectsender,EventArgse)  
  19. {  
  20. stringstringmessage=string.Format("The{0}eventof{1}isfired","Click","Button1");  
  21. this.LabelMessage.Text=message;  
  22. }  
  23. protectedvoidButton2_Click(objectsender,EventArgse)  
  24. {  
  25. stringstringmessage=string.Format("The{0}eventof{1}isfired","Click","Button2");  
  26. this.LabelMessage.Text=message;  
  27. }  
  28. protectedvoidButton3_Click(objectsender,EventArgse)  
  29. {  
  30. stringstringmessage=string.Format("The{0}eventof{1}isfired","Click","Button3");  
  31. this.LabelMessage.Text=message;  
  32. }  
  33.  
  34. protectedvoidButton_Command(objectsender,CommandEventArgse)  
  35. {  
  36. stringstringmessage=string.Format("The{0}eventof{1}isfired",
    "Command",e.CommandArgument);  
  37. this.LabelMessage.Text+=";"+message;  
  38. }  
  39. }  

　　以上介绍ASP.NET Postback的Web Page生命周期.