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asp+语法介绍(五)----asp+的服务器端编程控件篇

减小字体 增大字体 作者:不详  来源:不详  发布时间:2006-8-13 0:56:34
     使用定制的服务器控件
  在asp+中提供了45个已经做好了的服务器控件,我们可以将他们象黑盒子一样的使用。除此以外,开发者还可以使用任何第三方开发的服务器控件
  在下面的例子中,我们要用到一个通过<acme:calendar runat=server>标签声明的组件,请注意,在文件的第一行必须使用<% Register %> 来声明 "Acme Xml "标签的的前缀"Acme".在asp+ 文件中,将会使用这个命名的服务器控件的类的实例。
  <%@ Register TagPrefix="Acme" Namespace="Acme" %>
  
  <html>
   <head>
   <link rel="stylesheet"href="intro.css">
   </head>
  
   <script language="VB" runat=server>
  
   Sub SubmitBtn_Click(Sender As Object, E As EventArgs)
   Message.Text = "Hi " & Name.Text & ", you selected: " & Category.SelectedItem.Text & " on: " & MyCal.Date
   End Sub
  
   </script>
  
   <body>
  
   <center>
  
   <form action="intro7.aspx" method="post" runat="server">
  
   <asp:adrotator AdvertisementFile="ads.xml" BorderColor="black" BorderWidth=1 runat="server"/>
  
   <h3> Name: <asp:textbox id="Name" runat="server"/>
  
   Category: <asp:dropdownlist id="Category" runat=server>
   <asp:listitem >psychology</asp:listitem>
   <asp:listitem >business</asp:listitem>
   <asp:listitem >popular_comp</asp:listitem>
   </asp:dropdownlist>
  
   <asp:button type=submit text="Lookup" runat="server"/>
  
   <p>
  
   <Acme:Calendar id="MyCal" runat=server/>
  
   <p>
  
   <asp:label id="Message" runat="server"/>
  
   </form>
  
   </center>
  
   </body>
  </html>
  
  声明Acme 的 文件
  using System;
  using System.Web;
  using System.Web.UI;
  using System.Collections;
  
  namespace Acme
  {
   public class Calendar : Control, IPostBackEventHandler, IPostBackDataHandler
   {
   private String[] monthNames = new String[12];
   private DateTime currentDate = DateTime.Now;
   private String backColor = "#dcdcdc";
   private String foreColor = "#eeeeee";
  
   protected override void Init()
   {
   // Todo: We should remove the need to call this
   Page.RegisterRequiresPostBack(this);
   Page.RegisterPostBackScript();
  
   currentDate = DateTime.Now;
  
   // Todo: Hack needed because COOL doesn't support array initializers yet
   monthNames[0] = "January";
   monthNames[1] = "February";
   monthNames[2] = "March";
   monthNames[3] = "April";
   monthNames[4] = "May";
   monthNames[5] = "June";
   monthNames[6] = "July";
   monthNames[7] = "August";
   monthNames[8] = "September";
   monthNames[9] = "October";
   monthNames[10] = "November";
   monthNames[11] = "December";
   }
  
   protected override void LoadState(Object viewState)
   {
   // If we've done a post-back, the old date will be available to us
  
   if (null != viewState)
   {
   currentDate = DateTime.Parse((String) viewState);
   }
   }
  
   public void RaisePostBackEvent(String eventArgument)
   {
   //Page.Response.Write("RaisePostBackEvent Called!!!");
  
   if (eventArgument == null)
   {
   return;
   }
  
   // Keep track of old date (for event firing purposes)
  
   DateTime oldDate = currentDate;
  
   // Todo: We should have post-back take two arguments: eventname and eventarguments
  
   if (String.Compare("NavNextMonth", eventArgument, true) == 0)
   {
   currentDate = currentDate.AddMonths(1);
   }
   else if (String.Compare("NavPrevMonth", eventArgument, true) == 0)
   {
   currentDate = currentDate.AddMonths(-1);
   }
   else
   {
   int daySelected = Int32.Parse(eventArgument);
   currentDate = new DateTime(currentDate.Year, currentDate.Month, daySelected);
   }
   }
  
   protected override Object SaveState()
   {
   // Save CurrentDate out as view state for postback scenarios
  
   return currentDate.ToString();
   }
  
   protected override void Render(HtmlTextWriter output)
   {
   //Response.Write(Page.Request.UserAgent);
  
   if (Page.Request.UserAgent.IndexOf("MSIE 5.5") != -1)
   RenderUpLevel(output);
   else
   RenderDownLevel(output);
   }
  
   protected void RenderUpLevel(HtmlTextWriter output)
   {
   output.WriteLine("<input name='" + UniqueID + "_CurrentDate' id='" + UniqueID + "_CurrentDate' type=hidden>");
   output.WriteLine("<span id='" + UniqueID + "'></span>");
   output.WriteLine("<script language=jscript>drawcalendar('" + UniqueID + "', '" + Int32.Format(currentDate.Year, null) + "/" + Int32.Format(currentDate.Month, null) + "/" + Int32.Format(currentDate.Day, null) + "');</script>");
   }
  
   protected override void PreRender()
   {
   String DHTMLFunction = "";
  
   DHTMLFunction += "<script lang

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