ASP.NET自定义Web服务器控件-DropDownList/Select下拉列表控件

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Linq;

using System.Text;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

//自定义web服务器控件-下拉列表

namespace MyControls

{

    [DefaultProperty("Text")]

    [ToolboxData("<{0}:MySelect runat=server></{0}:MySelect>")]

    [ParseChildren(true,"Items")] //规定

    public class MySelect : WebControl

    {

        [Bindable(true)]

        [Category("Appearance")]

        [DefaultValue("")]

        [Localizable(true)]

        public string Text

        {

            get

            {

                String s = (String)ViewState["Text"];

                return ((s == null) ? String.Empty : s);

            }

            set

            {

                ViewState["Text"] = value;

            }

        }

        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)] //以内容的形式打印标签

        public List<SelectItem> Items{

           get{

            if(ViewState["Items"]==null){

                ViewState["Items"] = new List<SelectItem>();

            }

               return (List<SelectItem>)ViewState["Items"];

           }

            set{

                ViewState["Items"] = value;

            }

        }

        [DesignerSerializationVisibility(DesignerSerializationVisibility.Content)]//以内容的形式打印标签

        public Size Size

        {

            get

            {

                if (ViewState["Size"] == null)

                {

                    ViewState["Size"] = new Size();

                }

                return (Size)ViewState["Size"];

            }

            set

            {

                ViewState["Size"] = value;

            }

        }

        public override void RenderBeginTag(HtmlTextWriter writer)

        {

            this.Style.Add("Width", Size.Width + "px"); //增加样式，宽度

            this.Style.Add("Height", Size.Height + "px"); //增加样式，高度

            base.RenderBeginTag(writer);

        }

        protected override HtmlTextWriterTag TagKey

        {

            get

            {

                return HtmlTextWriterTag.Select;//下拉列表标签

            }

        }

        protected override void RenderContents(HtmlTextWriter output)

        {

            //打印下拉列表内容

            foreach(SelectItem item in Items){

                output.Write("<option value='"+item.Value+"'>"+item.Text+"</option>");

            }

        }

    }

}

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

//<!--自定义服务器下拉列表控件的子标签

namespace MyControls

{

    public class SelectItem

    {

        public string Value { set; get; } //选择的值

        public string Text { set; get; } //选择的文本内容

        public SelectItem() { }

        public SelectItem(string text, string value) {

            this.Text = text;

            this.Value = value;

        }

    }

}

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

 //<cc1:MyButton ID="MyButton1" Size-Height="30" Size-Width="290"  />用法，用于这种内部属性

//定义一个大小的类，里面包含了宽高

namespace MyControls

{

   public class Size

    {

       public int Width { set; get; }

       public int Height { set; get; }

       public Size(int width,int height) {

           this.Width = width;

           this.Height = height;

       }

       public Size() : this(100,100) { }

    }

}

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>

<%@ Register assembly="MyControls" namespace="MyControls" tagprefix="cc1" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">

<head runat="server">

    <title></title>

</head>

<body>

    <form id="form1" runat="server">

    <div>

    <!--自定义服务器下拉列表控件-->

        <cc1:MySelect Size-Height="100" Size-Width="100" ID="MySelect1" runat="server">

        <cc1:SelectItem Value="1" Text="选择一" />

        <cc1:SelectItem Value="2" Text="选择二" />

        <cc1:SelectItem Value="3" Text="选择三" />

        </cc1:MySelect>

    </div>

    </form>

</body>

</html>

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ASP.NET自定义Web服务器控件-DropDownList/Select下拉列表控件

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