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AdRotator.Render أسلوب

Visual Studio 2010

بعرض AdRotatorعنصر تحكم تشغيل العميل.

مساحة الاسم:  System.Web.UI.WebControls
التجميع:  System.Web (في System.Web.dll)

protected internal override void Render(
	HtmlTextWriter writer


النوع: System.Web.UI.HtmlTextWriter
Displays a فحص صندوق that allows the مستخدم إلى تحديد a System.Web.UI.HtmlTextWriter أو شرط.

It هو فقط possible إلى الوصول an ملف XML that هو located في a different تطبيق تشغيل the same موقع if the تطبيق has sufficient الثقة.OnPreRender

The following code example demonstrates how to override the Render method in a custom server control so that the AdRotator displays a random advertisement, from an XML file, with a link and an image.

<%@ Register TagPrefix="aspSample" Namespace="Samples.AspNet.CS.Controls" Assembly="Samples.AspNet.CS" %>
<%@ Page Language="C#" AutoEventWireup="True" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
<html xmlns="" >
    <title>Custom AdRotator - Render - C# Example</title>
    <form id="Form1" method="post" runat="server">
      <h3>Custom AdRotator - Render - C# Example</h3>

        AdvertisementFile="~/App_Data/Ads.xml" />



namespace Samples.AspNet.CS.Controls
  [System.Security.Permissions.PermissionSet(System.Security.Permissions.SecurityAction.Demand, Name="FullTrust")]
  public class CustomADRotatorRender : System.Web.UI.WebControls.AdRotator
    private const string ApplicationCachePrefix = "CustomAdRotatorCache: ";

    protected override void Render(System.Web.UI.HtmlTextWriter writer)
      string navigateUrl = System.String.Empty;
      string imageUrl = System.String.Empty;
      string alternateText = System.String.Empty;

      // If the value for the Advertisement File is not empty.
      if (this.AdvertisementFile.Length > 0 ) 
        // Get a random ad.
        GetRandomAd(out imageUrl, out navigateUrl, out alternateText);

      // Create and render a new HyperLink Web control.
      System.Web.UI.WebControls.HyperLink bannerLink = new System.Web.UI.WebControls.HyperLink();
      foreach(string key in this.Attributes.Keys) 
        bannerLink.Attributes[key] = this.Attributes[key];
      if (this.ID != null && this.ID.Length > 0) 
        bannerLink.ID = this.ClientID;
      bannerLink.NavigateUrl = navigateUrl; 
      bannerLink.Target = this.Target;
      bannerLink.AccessKey = this.AccessKey;
      bannerLink.Enabled = this.Enabled;
      bannerLink.TabIndex = this.TabIndex;

      // Create and render a new Image Web control.
      System.Web.UI.WebControls.Image bannerImage = new System.Web.UI.WebControls.Image();
      if (ControlStyleCreated) 
      bannerImage.AlternateText = alternateText;   
      bannerImage.ImageUrl = imageUrl;   
      bannerImage.ToolTip = this.ToolTip;

    private void GetRandomAd(out string imageUrl, out string navigateUrl, out string alternateText) 
      // Default output parameters values.
      imageUrl = System.String.Empty;
      navigateUrl = System.String.Empty;
      alternateText = System.String.Empty;

      // Try to get the Ads DataSet from the ASP.NET cache.
      string physicalPath = MapPathSecure(this.AdvertisementFile);
      string fileKey = ApplicationCachePrefix + physicalPath;
      System.Web.Caching.Cache cache = System.Web.HttpContext.Current.Cache;
      System.Data.DataSet dataSet = cache[fileKey] as System.Data.DataSet;

      // If the Ads DataSet was not found in the ASP.NET cache.
      if (dataSet == null) 
        // Get the Ads from an XML file.
        dataSet =  new System.Data.DataSet();
        dataSet.ReadXml(physicalPath, System.Data.XmlReadMode.InferSchema);

        // Insert the DataSet into the Cache.
        // Make sure your AntiVirus software doesn't touch the XMLf file, 
        // or else the cache will be empty each time the Render method gets called.
        cache.Insert(fileKey, dataSet, new System.Web.Caching.CacheDependency(physicalPath));

      // If Ads were found in the XML File.
      int totalAds = dataSet.Tables[0].Rows.Count;
      if (totalAds > 0)
        // Select a random Ad.
        System.Random randomNumber = new System.Random();
        int selectedAdIndex = randomNumber.Next(totalAds);

        // Output the random Ad's values.
        imageUrl = dataSet.Tables[0].Rows[selectedAdIndex].ItemArray[0].ToString();
        navigateUrl = dataSet.Tables[0].Rows[selectedAdIndex].ItemArray[1].ToString();
        alternateText = dataSet.Tables[0].Rows[selectedAdIndex].ItemArray[2].ToString();

نظام التشغيل Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, الإصدار x64 من نظام التشغيل Windows XP Professional, Windows XP Starter Edition, Windows Server 2008, نظام التشغيل Windows Server 2003, نظام التشغيل Windows Server 2000 المزود بحزمة الخدمة SP4, نظام التشغيل Windows Millennium Edition, نظام التشغيل Windows 98

لا يدعم .NET Framework و .NET Compact Framework كافة الإصدارات الخاصة بكل نظام أساسي. للحصول على قائمة بالإصدارات المدعمة، راجع متطلبات النظام إطار عمل .NET.

.NET Framework

مدعوم في: 4, 3.5, 3.0, 2.0, 1.1, 1.0