測試中，我發現要調用服務器端代碼必須調用__doPostBack函數，但該函數除了在放置有DataGrid控件的頁面中會由系統產生外，其他的頁面中並不存在。（可以通過查看源文件看到該代碼）。這樣我們必須手工在aspx中添加__doPostBack函數，和函數一起添加的還有兩個隱藏元素，__EVENTTARGET和__EVENTARGUMENT，這是__doPostBack所必須的，實際上，.NET是把產生事件的元素名稱以及參數傳到，__EVENTTARGET和__EVENTARGUMENT。然後再調用Form的submit函數提交回服務器的，服務器端根據傳回來的參數就知道是哪個控件被觸發了，從而調用它的相應後端代碼，然後再將新頁面回送回客戶端的。
以下是我的測試頁面，其中使用了兩種方法來檢測TextBox中的按鍵
WebForm2.aspx
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<%@ Page language="c#" Codebehind="WebForm2.aspx.cs" AutoEventWireup="false" Inherits="UTF8Test.WebForm2" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" ><HTML> <HEAD> <title>WebForm2</title> <meta content="Microsoft Visual Studio .NET 7.1" name="GENERATOR"> <meta content="C#" name="CODE_LANGUAGE"> <meta content="javascript" name="vs_defaultClientScript"> <meta content="http://schemas.microsoft.com/intellisense/ie5"; name="vs_targetSchema"> <script language="javascript" event="onkeydown" for="TextBox1">
if(event.keyCode==13)<!-- 注意大小寫-->
{ __doPostBack('Button1',''); return false;<!--很重要，不然會選擇Button1進行提交 -->
} 
</script> <script language="javascript" event="onkeydown" for="TextBox2"> if(event.keyCode==13) { __doPostBack('Button2',''); return false;<!--很重要，不然會選擇Button1進行提交 --> } </script> <script language="javascript"> function keypress() { if(event.keyCode==13) { __doPostBack('Button3',''); event.keyCode=0; <!--很重要，不然會選擇Button1進行提交 --> return false;<!--很重要，不然會選擇Button1進行提交 --> } } </script> </HEAD> <body MS_POSITIONING="GridLayout"> <form id="Form1" method="post" runat="server"> <input type="hidden" name="__EVENTTARGET"> <input type="hidden" name="__EVENTARGUMENT"> <script language="javascript" type="text/javascript"><!-- function __doPostBack(eventTarget, eventArgument) { var theform; if (window.navigator.appName.toLowerCase().indexOf("microsoft") > -1) { theform = document.Form1; } else { theform = document.forms["Form1"]; } theform.__EVENTTARGET.value = eventTarget.split("$").join(":"); theform.__EVENTARGUMENT.value = eventArgument; theform.submit(); }// --> </script> <asp:button id="Button1" style="Z-INDEX: 101; LEFT: 192px; POSITION: absolute; TOP: 88px" runat="server" Text="Button1"></asp:button><asp:textbox id="TextBox1" style="Z-INDEX: 102; LEFT: 16px; POSITION: absolute; TOP: 88px" runat="server"></asp:textbox> <asp:Button id="Button2" style="Z-INDEX: 103; LEFT: 192px; POSITION: absolute; TOP: 120px" runat="server" Text="Button2"></asp:Button> <asp:TextBox id="TextBox2" style="Z-INDEX: 104; LEFT: 16px; POSITION: absolute; TOP: 120px" runat="server"></asp:TextBox> <asp:TextBox id="TextBox3" style="Z-INDEX: 105; LEFT: 16px; POSITION: absolute; TOP: 152px" runat="server"></asp:TextBox> <asp:Button id="Button3" style="Z-INDEX: 106; LEFT: 192px; POSITION: absolute; TOP: 152px" runat="server" Text="Button3"></asp:Button> <asp:Label id="Label1" style="Z-INDEX: 107; LEFT: 24px; POSITION: absolute; TOP: 56px" runat="server"></asp:Label></form> </body></HTML>WebForm2.aspx.cs
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using System;using System.Collections;using System.ComponentModel;using System.Data;using System.Drawing;using System.Web;using System.Web.SessionState;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.HtmlControls;namespace UTF8Test{ /// <summary> /// WebForm2 的摘要說明。 /// </summary> public class WebForm2 : System.Web.UI.Page { protected System.Web.UI.WebControls.TextBox TextBox1; protected System.Web.UI.WebControls.Button Button2; protected System.Web.UI.WebControls.TextBox TextBox2; protected System.Web.UI.WebControls.TextBox TextBox3; protected System.Web.UI.WebControls.Button Button3; protected System.Web.UI.WebControls.Label Label1; protected System.Web.UI.WebControls.Button Button1; private void Page_Load(object sender, System.EventArgs e) { // 在此處放置用戶代碼以初始化頁面 TextBox3.Attributes.Add("onkeypress","keypress()");//注意大小寫 }
Web 窗體設計器生成的代碼 private void Button1_Click(object sender, System.EventArgs e) { Label1.Text = "1"; } private void Button2_Click(object sender, System.EventArgs e) { Label1.Text = "2"; } private void Button3_Click(object sender, System.EventArgs e) { Label1.Text = "3"; } }}