自定义控件中的自定义事件

 

using System;
using System.ComponentModel;
using System.Web.UI;
using System.Web.UI.WebControls;

//一个简单的应用用户自定义事件的用户自定义控件
namespace CustomComponents
{
    [
    DefaultEvent("ClickNext"),  //元数据 定义默认事件
    DefaultProperty("NextText") //元数据 定义默认属性
    ]
    public class NavButtons1 :Control, IPostBackEventHandler  //很重要一定要继承IPostBackEventHandler
    {                                                         //只有继承了这个接口才可以回传事件

        事件部分#region 事件部分

         private static readonly object EventClickNiu = new object();

        //声明一个代理
        public delegate void NiuEventHandler(object sender, NiuEventArgs e);

        //声明事件
        public event NiuEventHandler Niu
        {
            add
            {
                Events.AddHandler(EventClickNiu, value);
            }
            remove
            {
                Events.RemoveHandler(EventClickNiu, value);
            }
        }

        protected virtual void OnM(NiuEventArgs e)
        {
            NiuEventHandler niuEventHandler = (NiuEventHandler)Events[EventClickNiu];
            if (niuEventHandler != null)
                niuEventHandler(this, e);
        }

        #endregion

        声明属性#region 声明属性
        [
        Bindable(true),
        Category("Behavior"),
        DefaultValue(""),
        Description("The text to display on the Next button")
        ]
        public virtual string NextText
        {
            get
            {
                //利用ViewState保存状态
                string s = (string)ViewState["NextText"];
                return ((s == null) ? String.Empty : s);
            }
            set
            {
                ViewState["NextText"] = value;
            }
        }

        [
        Bindable(true),
        Category("Behavior"),
        DefaultValue(""),
        Description("The text to display on the middle button")
        ]
        public virtual string MiddleText
        {
            get
            {
                return(ViewState["middleText"] == null)?string.Empty: (string)ViewState["middleText"];
            }
            set
            {
                ViewState["middleText"] = value;
            }
        }

        [
        Bindable(true),
        Category("Behavior"),
        DefaultValue(""),
        Description("The text to display on the Previous button")
        ]
        public virtual string PreviousText
        {
            get
            {
                string s = (string)ViewState["PreviousText"];
                return ((s == null) ? String.Empty : s);
            }
            set
            {
                ViewState["PreviousText"] = value;
            }
        }
        #endregion

        回传事件，生成控件#region 回传事件，生成控件
        [
        Category("Action"),
        Description("Raised when the Next button is clicked")
        ]
        //回传事件 并根据回传参数判断客户到底点击了那个按钮
        void IPostBackEventHandler.RaisePostBackEvent(string eventArgument)
        {
            if (eventArgument == "Previous")
            {
                NiuEventArgs e = new NiuEventArgs(eventArgument);
                OnM(e);
                PreviousText = "你点击了PreviousText按钮";
            }
            else if (eventArgument == "Next")
            {
                NiuEventArgs e = new NiuEventArgs(eventArgument);
                OnM(e);
                NextText = "你点击了NextText按钮";
            }
            else if (eventArgument == "Middle")
            {
                NiuEventArgs e = new NiuEventArgs(eventArgument);
                OnM(e);
                MiddleText = "你点击了MiddleText按钮";
            }
        }
        
        //使用Render方法生成控件，如果是继承自WebControl最后使用RenderContent（）方法
        protected override void Render(HtmlTextWriter writer)
        {
            writer.AddAttribute(HtmlTextWriterAttribute.Onclick, Page.GetPostBackEventReference(this, "Previous"));
            writer.AddAttribute(HtmlTextWriterAttribute.Name, "NextButton");
            writer.RenderBeginTag(HtmlTextWriterTag.Button);
            writer.Write(this.PreviousText);
            writer.RenderEndTag();

            writer.AddAttribute(HtmlTextWriterAttribute.Onclick, Page.GetPostBackEventReference(this,"Middle"));
            writer.RenderBeginTag(HtmlTextWriterTag.Button);
            writer.Write(MiddleText);
            writer.RenderEndTag();

            writer.AddAttribute(HtmlTextWriterAttribute.Onclick, Page.GetPostBackEventReference(this, "Next"));
            writer.RenderBeginTag(HtmlTextWriterTag.Button);
            writer.Write(this.NextText);
            writer.RenderEndTag();
        }
        #endregion
    }

    定义一个用户自定义事件参数#region 定义一个用户自定义事件参数
    public class NiuEventArgs : EventArgs
    {
        private string btnName;
        public NiuEventArgs(string name)
        {
            btnName = name;
        }
        public string Name
        {
            get
            {
                return btnName;
            }
        }
    }
    #endregion
}