如何在代码隐藏中用控件替换占位符

本文关键字：控件 替换 占位符 隐藏 代码 | 更新日期: 2023-09-27 18:27:59

我想让我的用户能够创建带有占位符的模板，比如##CreateLink##，它应该在代码后面用控件替换。

我知道如何在运行时创建控件，但不知道如何用这些动态创建的控件替换占位符。

我怎样才能做到这一点？

这是我的.aspx代码

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Literal ID="lit" runat="server" Text="This is my sample text. Here is my ##token## which should be replaced by my control in codebehind..."></asp:Literal>
    </div>
    </form>
</body>
</html>

这是我的代码头：

   public partial class WebForm1 : System.Web.UI.Page
    {
        private HyperLink lnk;
        protected override void CreateChildControls()
        {
            base.CreateChildControls();
            lnk = new HyperLink();
            lnk.ID = "lnk";
            lnk.NavigateUrl = "http://www.google.com";
        }
        protected void Page_Load(object sender, EventArgs e)
        {
        }
        protected override void Render(HtmlTextWriter writer)
        {
            base.Render(writer);
        }
    }

如何在代码隐藏中用控件替换占位符

使用另一个答案来指导我，我得出了以下结果：

.aspx标记

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="WebApplication2.WebForm1" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:Literal ID="lit" runat="server" Text="This is my sample text. Here is my ##token## and my button ##button## which should be replaced by my control in codebehind..."></asp:Literal>
        <p>this is a default button</p>
        <asp:Button ID="btn2" runat="server" text="from asp.net" />
    </div>
    </form>
</body>
</html>

C#代码隐藏代码

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
namespace WebApplication2
{
    public partial class WebForm1 : System.Web.UI.Page
    {
        private HyperLink lnk;
        private Button btn;
        protected override void CreateChildControls()
        {
            base.CreateChildControls();
            lnk = new HyperLink();
            lnk.ID = "lnk";
            lnk.Text = "<b>Sample Link</b>";
            lnk.NavigateUrl = "http://www.google.com";
            btn = new Button();
            btn.ID = "btn";
            btn.Text = "button text";
        }
        protected void Page_Load(object sender, EventArgs e)
        {
        }
        protected override void Render(HtmlTextWriter writer)
        {
            StringBuilder sb = new StringBuilder();
            HtmlTextWriter myWriter = new HtmlTextWriter(new System.IO.StringWriter(sb, System.Globalization.CultureInfo.InvariantCulture));
            base.Render(myWriter);
            myWriter.Flush();
            string renderedHtml = sb.ToString();
            renderedHtml = renderedHtml.Replace("##token##", RenderHTML(lnk));
            renderedHtml = renderedHtml.Replace("##button##", RenderHTML(btn));
            writer.Write(renderedHtml);
            myWriter.Close();
            sb.Clear();
        }
        private string RenderHTML(Control ctrl)
        {
            StringBuilder sb = new StringBuilder();  
            HtmlTextWriter myWriter = new HtmlTextWriter(new System.IO.StringWriter(sb, System.Globalization.CultureInfo.InvariantCulture));
            ctrl.RenderControl(myWriter);
            myWriter.Close();
            return sb.ToString();
        }
    }
}

使用渲染方法

protected override void Render(HtmlTextWriter writer)
{
        //Place replace logic
}

更新

protected override void Render(HtmlTextWriter writer)
{
    MemoryStream stream = new MemoryStream();
    StreamWriter memWriter = new StreamWriter(stream);
    HtmlTextWriter myWriter = new HtmlTextWriter(memWriter);
    base.Render(myWriter);
    myWriter.Flush();
    stream.Position = 0;
    string renderedHtml = new StreamReader(stream).ReadToEnd();
    renderedHtml = renderedHtml.Replace("##token##", "VALUE");
    writer.Write(renderedHtml);
    writer.Close();
    myWriter.Close();
    stream.Close();
}
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