使用Asp.net进行开发时，因为某些需求原因，需要在页面中动态添加控件。当然，这些控件可以是普通的html标签，也可以是Asp.net独有的服务器端控件。关于动态写入html标签控件，大家都熟悉，这里就不再表述。本文讨论的重点是：如何动态写入服务器端控件，并且在页面PostBack到Server端时，在Server端来获取被动态写入的服务器端控件的各种属性。

这里，我来通过一个Demo来说明这个应用。

需求：

1. 用户在UI上输入一个数值(比如：5)，系统动态为用户加载这个数值的Url Address输入域;

2. 用户输入的Url Address内容需要通过Url格式验证;

3. 用户提交输入内容后，系统给出提交的结果

设计如下：

1. Css样式设置：

以下为引用的内容：   <style type="text/css">         .item         {         margin:10px;         border-bottom:solid 1px #CCC;         }                 .item2         {         margin:5px;         }                 .input         {         width:200px;         } </style> 2．前台页面代码：         <div>               <div class="item">                 Please input a number:                 <asp:TextBox runat="server" CssClass="item" ID="txtTextCount"></asp:TextBox>                 <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtTextCount" ValidationGroup="CreateTextBox" Display="Dynamic"                     ErrorMessage="Required to input content!"></asp:RequiredFieldValidator>                 <asp:RegularExpressionValidator ID="RegularExpressionValidator1" ControlToValidate="txtTextCount" ValidationGroup="CreateTextBox" Display="Dynamic"                     runat="server" ErrorMessage="Only number is valid!" ValidationExpression="^\d+$"></asp:RegularExpressionValidator>&nbsp;&nbsp;                 <asp:Button runat="server" ID="btnCreate" Text="Create TextBox List" ValidationGroup="CreateTextBox"                     onclick="btnCreate_Click" />&nbsp;&nbsp;                 <asp:Button runat="server" ID="btnOK" Text="Get TextBox Content" ValidationGroup="ShowListContent"                     onclick="btnOK_Click" />             </div>             <div runat="server" id="divControls" class="item"></div>             <div runat="server" id="divMessage">                            </div>         </div>

2． 前台页面代码：

以下为引用的内容：        <div>               <div class="item">                 Please input a number:                 <asp:TextBox runat="server" CssClass="item" ID="txtTextCount"></asp:TextBox>                 <asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ControlToValidate="txtTextCount" ValidationGroup="CreateTextBox" Display="Dynamic"                     ErrorMessage="Required to input content!"></asp:RequiredFieldValidator>                 <asp:RegularExpressionValidator ID="RegularExpressionValidator1" ControlToValidate="txtTextCount" ValidationGroup="CreateTextBox" Display="Dynamic"                     runat="server" ErrorMessage="Only number is valid!" ValidationExpression="^\d+$"></asp:RegularExpressionValidator>&nbsp;&nbsp;                 <asp:Button runat="server" ID="btnCreate" Text="Create TextBox List" ValidationGroup="CreateTextBox"                     onclick="btnCreate_Click" />&nbsp;&nbsp;                 <asp:Button runat="server" ID="btnOK" Text="Get TextBox Content" ValidationGroup="ShowListContent"                     onclick="btnOK_Click" />             </div>             <div runat="server" id="divControls" class="item"></div>             <div runat="server" id="divMessage">                            </div>         </div>

说明， 动态创建的TextBox们将装载到divControls中。

3． 后台代码：

以下为引用的内容：        ///<summary>         /// Create textbox list         ///</summary>         ///<param name="num">textbox list count</param>         private void CreateTextBoxList(int num)         {             HtmlGenericControl div;             HtmlGenericControl span;             TextBox txt;             RegularExpressionValidator rev;               for (int i = 0; i < num; i++)             {                 //创建div                 div = new HtmlGenericControl();                 div.TagName = "div";                 div.ID = "divTextBox" + i.ToString();                 div.Attributes["class"] = "item2";                   //创建span                 span = new HtmlGenericControl();                 span.ID = "spanTextBox" + i.ToString();                 span.InnerHtml = "Url Address" + (i+1).ToString() + ":";                   //创建TextBox                 txt = new TextBox();                 txt.ID = "txt" + i.ToString();                 txt.CssClass = "input";                   //创建格式验证控件，并且将其关联到对应的TextBox                 rev = new RegularExpressionValidator();                 rev.ID = "rev" + i.ToString();                 rev.ControlToValidate = txt.ID;                 rev.Display = ValidatorDisplay.Dynamic;                 rev.ValidationGroup = "ShowListContent";                 rev.ValidationExpression = @"(http(s)?://)?([\w-]+\.)+[\w-]+(/[\w- ./?%&amp;=]*)?";                 rev.ErrorMessage = "Invalid url Address!";                   //添加控件到容器                 div.Controls.Add(span);                 div.Controls.Add(txt);                 div.Controls.Add(rev);                 divControls.Controls.Add(div);             }         }           protected void Page_Load(object sender, EventArgs e)         {             if (this.IsPostBack)             {                 int txtCount = int.Parse(txtTextCount.Text);                   // 注意：每次PostBack时，都需要重新动态创建TextBox                 CreateTextBoxList(txtCount);             }         }           protected void btnCreate_Click(object sender, EventArgs e)         {             txtTextCount.Enabled = false;             btnCreate.Enabled = false;         }           protected void btnOK_Click(object sender, EventArgs e)         {             TextBox txt;             StringBuilder sbResult = new StringBuilder() ;             int txtCount = int.Parse(txtTextCount.Text);               //遍历获取动态创建的TextBox们中的Text值             for (int i = 0; i < txtCount; i++)             {                 //注意：这里必须通过上层容器来获取动态创建的TextBox，才能获取取ViewState内容                 txt = divControls.FindControl("txt" + i.ToString()) as TextBox;                   if (txt != null && txt.Text.Trim().Length > 0)                 {                     sbResult.AppendFormat("Url Address{0}: {1}.<br />", i+1, txt.Text.Trim());                 }             }               divMessage.InnerHtml = sbResult.ToString();         }

4.       效果图：

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