ASP.NET自定义控件组件开发 第四章 组合控件开发CompositeControl 后篇 －－事件冒泡

                             CompositeControl  后篇 －－事件冒泡

 

    我们上一篇已经开发一个登录的组合控件，但是我们把控件的事件的这个问题没有解决，现在我们就来看看这个问题。

 

    因为我们的组合控件Login是由一些已经存在的服务器控件的组合的，这样就省却了我们很多的麻烦，上篇中我们已经把子控件的一些属性，如Text等，显示呈现为了组合控件的属性。我们将之称为“属性的冒泡”（我自己这样认为的）。

 

    我们现在来想下：其实我们点击“提交”按钮，我们就想把控件中信息发送给服务器，然后验证。即，我们点击的是“提交”按钮，但是触发的确实Login控件的验证事件。也就是说，我们应该把子控件－button的事件，上升冒泡成为Login的事件。

 

    现在我们就正式讲讲怎么来事件冒泡。

 

    对于事件的一些步骤，大家应该还记得：    

      

    1。定义一个数据类，用来当发生事件时，我们把一些信息携带。在本控件中，当我们点击“提交”按钮时，我们就把用户名和密码作为数据送到服务器。所以我们的数据类包含两个信息：如下：

 

public class ValidateEventArgs : EventArgs
{
    private string userName;
    private string userPassward;

    public string UserName
    {
        get
        {
            return userName;
        }
    }

    public string UserPassward
    {
        get
        {
            return userPassward;
        }
    }

    public ValidateEventArgs(string username, string userpassward)
    {
        this.userName = username;
        this.userPassward = userpassward;
    }
}

 

    相信大家对上面的代码不陌生！！！

 

    2.我们来定义一个委托：

 

public delegate void ValidateEventHandler(object sender,ValidateEventArgs args);

 

    3.定义事件。

private static readonly object ValidateEventKey = new object();
    public event ValidateEventHandler ValidateUserInfoChanged
    {
        add
        {
            Events.AddHandler(ValidateEventKey, value);
        }
        remove
        {
            Events.RemoveHandler(ValidateEventKey, value);
        }
    }

    protected virtual void OnValidateChanged(ValidateEventArgs args)
    {
        ValidateEventHandler handler = Events[ValidateEventKey] as ValidateEventHandler;
        if (handler != null)
            handler(this, args);
    }

 

    4.好了；准备都做好了，下面我们只要把这个事件冒泡成为Login的控件的就行了。其实很简单的。只要重写一个方法就行了。如下：

   

protected override bool OnBubbleEvent(object source, EventArgs args)
    {
        bool handled = false;

        CommandEventArgs ce = args as CommandEventArgs;
        if (ce != null && ce.CommandName == "Validate")
        {
            handled = true;
            string userName = this.txtUserName.Text;
            string userPassward = this.txtUserPassward.Text;

            //把信息输入

            ValidateEventArgs ve = new ValidateEventArgs(userName, userPassward);
            OnValidateChanged(ve);
        }
        return handled;
    }

    好了，完了，就这样了。

    完整代码附上：

 

using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

namespace LoginControl
{
    public class Login : CompositeControl
    {
        #region 要组合的控件
        Label lbUserName;
        Label lbUserPassward;
        TextBox txtUserName;
        TextBox txtUserPassward;
        Button submitButton;
        #endregion


        #region 重写方法CreateChildControls

        protected override void CreateChildControls()
        {
            Controls.Clear();

            //初始化控件lbUserName

            lbUserName = new Label();
            lbUserName.Text = "用户名：";
            lbUserName.ID = "lbUserName";
            //把控件添加到我们的组合控件中

            Controls.Add(lbUserName);

            //初始化控件lbUserPassward

            lbUserPassward = new Label();
            lbUserPassward.Text = "密 码：";
            lbUserPassward.ID = "lbUserPassward";
            Controls.Add(lbUserPassward);


            txtUserName = new TextBox();
            txtUserName.ID = "txtUserName";
            txtUserName.Width = Unit.Percentage(60);
            Controls.Add(txtUserName);

            txtUserPassward = new TextBox();
            txtUserPassward.ID = "txtUserPassward";
            txtUserPassward.Width = Unit.Percentage(60);
            Controls.Add(txtUserPassward);

            submitButton = new Button();
            submitButton.Text = "提交";
            submitButton.CommandName = "Validate";
            Controls.Add(submitButton);

            ChildControlsCreated = true;
        }
        #endregion
        #region 将组合的子控件的属性 呈现为 组合控件的属性

        public string UserNameLabelText
        {
            get
            {
                EnsureChildControls();
                return lbUserName.Text;
            }
            set
            {
                EnsureChildControls();
                lbUserName.Text = value;
            }
        }

        public string UserPasswardLabelText
        {
            get
            {
                EnsureChildControls();
                return lbUserPassward.Text;
            }
            set
            {
                EnsureChildControls();
                lbUserPassward.Text = value;
            }
        }

        public string SubmitButtonText
        {
            get
            {
                EnsureChildControls();
                return submitButton.Text;
            }
            set
            {
                EnsureChildControls();
                submitButton.Text = value;
            }
        }


        #endregion

        #region 组合控件呈现的样式
        protected override HtmlTextWriterTag TagKey
        {
            get
            {
                return HtmlTextWriterTag.Table;
            }
        }

        protected override void RenderContents(HtmlTextWriter writer)
        {

            writer.RenderBeginTag(HtmlTextWriterTag.Tr);

            writer.RenderBeginTag(HtmlTextWriterTag.Td);
            lbUserName.RenderControl(writer);
            writer.RenderEndTag();//td的结束


            writer.RenderBeginTag(HtmlTextWriterTag.Td);
            txtUserName.RenderControl(writer);
            writer.RenderEndTag();

            writer.RenderEndTag();//tr的结束


            //***********************************************


            writer.RenderBeginTag(HtmlTextWriterTag.Tr);

            writer.RenderBeginTag(HtmlTextWriterTag.Td);
            lbUserPassward.RenderControl(writer);
            writer.RenderEndTag();//td的结束


            writer.RenderBeginTag(HtmlTextWriterTag.Td);
            txtUserPassward.RenderControl(writer);
            writer.RenderEndTag();

            writer.RenderEndTag();//tr的结束


            //***********************************************


            writer.RenderBeginTag(HtmlTextWriterTag.Tr);

            writer.AddAttribute(HtmlTextWriterAttribute.Colspan, "2");
            writer.AddAttribute(HtmlTextWriterAttribute.Align, "center");
            writer.RenderBeginTag(HtmlTextWriterTag.Td);
            submitButton.RenderControl(writer);
            writer.RenderEndTag();

            writer.RenderEndTag();//tr的结束





        }
        #endregion

        #region 事件
        private static readonly object ValidateEventKey = new object();
        public event ValidateEventHandler ValidateUserInfoChanged
        {
            add
            {
                Events.AddHandler(ValidateEventKey, value);
            }
            remove
            {
                Events.RemoveHandler(ValidateEventKey, value);
            }
        }

        protected virtual void OnValidateChanged(ValidateEventArgs args)
        {
            ValidateEventHandler handler = Events[ValidateEventKey] as ValidateEventHandler;
            if (handler != null)
                handler(this, args);
        }

        #endregion

        #region 冒泡

        protected override bool OnBubbleEvent(object source, EventArgs args)
        {
            bool handled = false;

            CommandEventArgs ce = args as CommandEventArgs;
            if (ce != null && ce.CommandName == "Validate")
            {
                handled = true;
                string userName = this.txtUserName.Text;
                string userPassward = this.txtUserPassward.Text;

                //把信息输入

                ValidateEventArgs ve = new ValidateEventArgs(userName, userPassward);
                OnValidateChanged(ve);
            }
            return handled;
        }
        #endregion



    }
}