Asp.net关于动态输出服务器控件的应用

    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：

    <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>

说明， 动态创建的TextBox们将装载到divControls中。

 

3． 后台代码：

        /// <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：

5. 源码下载：https://files.cnblogs.com/Langzi127/WebApplication1.zip