下面来看一个示例：
1)在VS2005中新建一个ASP.NET AJAX-Enabled Web Project项目工程，命名为ValidatorCalloutExtender1。
2)在页面上拖放2个TextBox,用于输入用户名和电话号码。同时对输入用户名的TextBox，加一个requiredFieldValidator；对输入电话号码的TextBox，加一个requiredFieldValidator和RegularExpressionValidator。同时对每个Validator扩展一个ValidatorCalloutExtender。
代码如下：
1<div>
2Name:
3<asp:TextBoxID="txtName"runat="server"></asp:TextBox>
4<asp:requiredFieldValidatorID="requiredFieldValidator1"runat="server"ControlToValidate="txtName"
5Display="None"ErrorMessage="Nameisrequired"></asp:requiredFieldValidator>
6<cc1:ValidatorCalloutExtenderID="ValidatorCalloutExtender1"runat="server"TargetControlID="requiredFieldValidator1">
7</cc1:ValidatorCalloutExtender>
8<br/>
9<br/>
10phone:
11<asp:TextBoxID="txtPhone"runat="server"OnTextChanged="TextBox2_TextChanged"></asp:TextBox>
12<asp:requiredFieldValidatorID="requiredFieldValidator2"runat="server"ControlToValidate="txtPhone"
13Display="None"ErrorMessage="phoneisrequired"></asp:requiredFieldValidator>
14<asp:RegularExpressionValidatorID="RegularExpressionValidator1"runat="server"ControlToValidate="txtPhone"
15Display="None"ErrorMessage="RegularExpressionValidator"ValidationExpression="(\(\d{3}\)|\d{3}-)?\d{8}"></asp:RegularExpressionValidator>
16<cc1:ValidatorCalloutExtenderID="ValidatorCalloutExtender2"runat="server"TargetControlID="requiredFieldValidator2">
17</cc1:ValidatorCalloutExtender>
18<cc1:ValidatorCalloutExtenderID="ValidatorCalloutExtender3"runat="server"TargetControlID="RegularExpressionValidator1">
19</cc1:ValidatorCalloutExtender>
20<br/>
21<br/>
22<asp:ButtonID="Button1"runat="server"Text="Button"/></div>
2Name:
3<asp:TextBoxID="txtName"runat="server"></asp:TextBox>
4<asp:requiredFieldValidatorID="requiredFieldValidator1"runat="server"ControlToValidate="txtName"
5Display="None"ErrorMessage="Nameisrequired"></asp:requiredFieldValidator>
6<cc1:ValidatorCalloutExtenderID="ValidatorCalloutExtender1"runat="server"TargetControlID="requiredFieldValidator1">
7</cc1:ValidatorCalloutExtender>
8<br/>
9<br/>
10phone:
11<asp:TextBoxID="txtPhone"runat="server"OnTextChanged="TextBox2_TextChanged"></asp:TextBox>
12<asp:requiredFieldValidatorID="requiredFieldValidator2"runat="server"ControlToValidate="txtPhone"
13Display="None"ErrorMessage="phoneisrequired"></asp:requiredFieldValidator>
14<asp:RegularExpressionValidatorID="RegularExpressionValidator1"runat="server"ControlToValidate="txtPhone"
15Display="None"ErrorMessage="RegularExpressionValidator"ValidationExpression="(\(\d{3}\)|\d{3}-)?\d{8}"></asp:RegularExpressionValidator>
16<cc1:ValidatorCalloutExtenderID="ValidatorCalloutExtender2"runat="server"TargetControlID="requiredFieldValidator2">
17</cc1:ValidatorCalloutExtender>
18<cc1:ValidatorCalloutExtenderID="ValidatorCalloutExtender3"runat="server"TargetControlID="RegularExpressionValidator1">
19</cc1:ValidatorCalloutExtender>
20<br/>
21<br/>
22<asp:ButtonID="Button1"runat="server"Text="Button"/></div>
3)按下CTRL+F5，在浏览器里查看效果。
效果图如下：
