带有多个PostBackData的处理

                 带有多个PostBackData的处理

在MSDN有关于IPostBackDataHandler的这样一个例子：

using System;

using System.Web;

using System.Web.UI;

using System.Collections.Specialized;

using System.ComponentModel;

 

namespace CustomComponents

{

    [ToolboxData("<{0}:Textbox1 runat=server></{0}:Textbox1>"),

    DefaultProperty("Text")]

    public class Textbox1 : Control, IPostBackDataHandler

    {

        public string Text

        {

            get

            {

                object text = ViewState["Text"];

                if (text == null)

                    return string.Empty;

                else

                    return (string)text;

            }

            set

            {

                ViewState["Text"] = value;

            }

        }

 

        public bool LoadPostData(string postDataKey,

           NameValueCollection postCollection)

        {

            string postedValue = postCollection[postDataKey];

            if (!Text.Equals(postedValue))

            {

                Text = postedValue;

                return true;

            }

            else

                return false;

        }

        public void RaisePostDataChangedEvent()

        {

            OnTextChanged(EventArgs.Empty);

        }

 

        protected virtual void OnTextChanged(EventArgs e)

        {

            if (TextChanged != null)

                TextChanged(this, e);

        }

 

        public event EventHandler TextChanged;

 

        protected override void Render(HtmlTextWriter writer)

        {

            base.Render(writer);

            Page.VerifyRenderingInServerForm(this);

            writer.Write("<INPUT type=/"text/" name=/"");

            writer.Write(this.UniqueID);

            writer.Write("/" value=/"" + this.Text + "/" />");

        }

    }

}

    这个例子很清晰的演示了怎样处理回发数据。但值得注意的是，该控件中客户端PostBack回的值只有一个，即在Render方法中只能看到一个name为this.UniqueID的TextBox，如果有多个TextBox的name为this.UniqueID，即有多个回发值该怎么获得各个值呢？

我们修改Render，再给它添加一个Textbox：

        protected override void Render(HtmlTextWriter writer)

        {

            base.Render(writer);

            Page.VerifyRenderingInServerForm(this);

            writer.Write("<INPUT type=/"text/" name=/"");

            writer.Write(this.UniqueID);

            writer.Write("/" value=/"" + this.Text + "/" />");

writer.Write("<INPUT type=/"text/" name=/"");

            writer.Write(this.UniqueID);

            writer.Write("/" value=/"" + this.Text + "/" />");

        }

   在LoadPostData中方法中设立断点，运行后在两个输入框中输入以下数据：

可以看到用string postedValue = postCollection[postDataKey];中postedValue值为121,asas，很明显，如果有多个PostBack值，这些值将以逗号隔开。