ASP.NET 2.0/3.5 一共提供了六个验证控件，在仔细了解了这几个验证控件后，才发现以前自己对验证控件有太多的误解，对其了解仅限于表象，对其应用也很不合理。以前我认为：
1. 验证控件和javascript的验证方式是一致的，都是通过js来进行验证
2. 验证控件太丑
3. 验证控件灵活度太差
效果和灵活度不如javascript的验证方式，这些控件最终还是会生成客户端的html和javascript，以上的这些都是对验证控件的误解。
在此章节开始之前，我先阐述并修正我对这些控件的误解。
1. 验证控件和javascript验证
验证控件通过服务器解释，最终呈现到浏览器，我们看到的仍然是一些html/css/js这些浏览器才能识别的语言，默认情况下它既在服务器端执行验证，也在客户端执行验证。服务端的验证是通过表单提交来实现，客户端的验证仍然是通过js来实现，这相当于执行了双重验证。但是js验证仅仅只是通过浏览器解释js脚本来进行验证。
2. 验证控件太丑
验证控件不是太丑，而是我不愿意为验证控件去写css，以前也一直认为验证控件就应该去写属性，但是写属性去调整一个控件，那代码就显得很臃肿，于是就产生了鄙视之的心理。
其实这是我先入为主的思想在作怪，我总是喜欢把客户端和服务器端的东西分开写，也许是Code Behind导致我精神分裂，喜欢把客户端和服务端的东西分的太清。
3. 验证控件灵活度差
验证控件在灵活度上确实不能和javascurip相比，它不能做出像javascript能够表现得动态效果，但是这并不代表它缺乏灵活度，如果足够了解这些控件，合理的结合使用其中的几种控件，也一样能够达到我们预期的效果（如果你正则表达式运用的比较好，只用RegularExpressionValidator控件就能完成所有验证）。
以上这些都是前话，现在开始正题，验证控件的讲述。
六个验证控件：
- RequireFieldValidator——用于要求用户在表单字段中输入必须的值。
- RangeValidator——用于检测一个值是否在确定的最小值和最大值之间。
- CompareValidator——用于比较一个值和另一个值或执行数据类型检查。
- RegularExpressValidator——用于比较一个值和正则表达式。
- CustomValidator——用于执行自定义验证。
- ValidationSummary——用于在页面中显示所有验证错误的摘要。
1.Page.IsValid属性，Display属性，Text属性
每一个验证控件都包含一个IsValid属性，验证正确则返回true，否则返回false。当页面中的所有验证控件的IsValid属性都为true时，Page.IsValid属性才返回true。
Display属性可接收的三个值：Static, Dynamic, None，Display的默认值是Static。
Text属性用于在验证失败时显示错误信息。
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: void btnSubmit_Click(Object sender, EventArgs e)
5: {
6: //了解Page.IsValid属性
7: if (Page.IsValid)
8: {
9: lblResult.Text = @"
Product:" + this.txtProductName.Text +
10: @"
" + "Price:" + this.txtProductPrice.Text +
11: @"
" + "Quantity:" + this.txtProductQuantity.Text;
12: }
13:
14: }
15: script>
16: <html xmlns="http://www.w3.org/1999/xhtml" >
17: <head id="Head1" runat="server">
18: <title>Order Formtitle>
19: <style type="text/css">
20: body{
21: font-size: 1em;
22: font-family: "微软雅黑";
23: color: #333333;
24: }
25: style>
26: head>
27: <body>
28: <form id="form1" runat="server">
29: <div>
30:
31: <fieldset>
32: <legend>Product Order Formlegend>
33:
34: <asp:Label
35: ID="lblProductName"
36: runat="server"
37: Text="Product Name:"
38: AssociatedControlID="txtProductName">asp:Label>
39: <asp:TextBox
40: ID="txtProductName"
41: runat="server">asp:TextBox>
42:
43: <asp:RequiredFieldValidator
44: ID="reqProductName"
45: runat="server"
46: Display="Static"
47: ControlToValidate="txtProductName"
48: Text="(Required)">asp:RequiredFieldValidator>
49: <br /><br />
50:
51: <asp:Label
52: ID="lblProductPrice"
53: runat="server"
54: Text="Product Price:"
55: AssociatedControlID="txtProductPrice">asp:Label>
56: <asp:TextBox
57: ID="txtProductPrice"
58: runat="server">asp:TextBox>
59:
60: <asp:RequiredFieldValidator
61: ID="reqProductPrice"
62: runat="server"
63: ControlToValidate="txtProductPrice"
64: Text="(Required)"
65: Display="Dynamic">asp:RequiredFieldValidator>
66: <asp:CompareValidator
67: ID="cmpProductPrice"
68: runat="server"
69: ControlToValidate="txtProductPrice"
70: Text="(Invalid Price)"
71: Operator="DataTypeCheck"
72: Type="Currency">asp:CompareValidator>
73: <br /><br />
74:
75: <asp:Label
76: ID="lblProductQuantity"
77: runat="server"
78: Text="Product Quantity:"
79: AssociatedControlID="txtProductQuantity">asp:Label>
80: <asp:TextBox
81: ID="txtProductQuantity"
82: runat="server">asp:TextBox>
83:
84: <asp:RequiredFieldValidator
85: ID="reqProductQuantity"
86: ControlToValidate="txtProductQuantity"
87: Text="(Required)"
88: Display="Dynamic"
89: runat="server">asp:RequiredFieldValidator>
90: <asp:CompareValidator
91: ID="cmpProductQuantity"
92: runat="server"
93: ControlToValidate="txtProductQuantity"
94: Text="(Invalud Quantity)"
95: Operator="DataTypeCheck"
96: Type="Currency">asp:CompareValidator>
97: <br /><br />
98:
99: <asp:Button
100: ID="btnSubmit"
101: runat="Server"
102: Text="Submit"
103: OnClick="btnSubmit_Click" />
104:
105: fieldset>
106:
107:
108: <asp:Label
109: ID="lblResult"
110: runat="server">asp:Label>
111:
112: div>
113:
114: form>
115: body>
116: html>
当Display属性值为Static时，验证控件生成的代码如下：
1: <span id="reqProductName" style="color:Red; visibility:hidden">(Required)span>
当Display属性值为Dynamic时，验证控件生成的代码则是：
1: <span id="reqProductPrice" style="color:Red; display:none">(Required)span>
虽然visibility属性和display属性都会隐藏文本，但是visiblity即使隐藏了文本，仍然会占用空间，而display属性则不会。
通常情况下，我们都应该设置验证控件的Display属性为Dynamic，当有多个验证控件去验证某个控件时（比如TextBox控件），验证错误时的文本不会被推到右边。
Display属性为None时，验证控件中的Text将不显示，但我们仍然可以通过ValidationSummary控件来进行显示。
事实上，Text属性接收任何HTML字符串，比如Text=”
”，以图片的形式来显示错误提示信息。
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: script>
5: <html xmlns="http://www.w3.org/1999/xhtml" >
6: <head id="Head1" runat="server">
7: <title>Validation Imagetitle>
8: head>
9: <body>
10: <form id="form1" runat="server">
11: <div>
12: <asp:Label ID="FirstName" runat="server" Text="First Name:" AssociatedControlID="txtFirstName">asp:Label>
13: <br />
14: <asp:TextBox ID="txtFirstName" runat="server">asp:TextBox>
15:
16:
17: <asp:RequiredFieldValidator
18: ID="reqFirstName"
19: runat="server"
20: SetFocusOnError="true"
21: Text="<img src='error.png'/>"
22: ControlToValidate="txtFirstName">asp:RequiredFieldValidator>
23: <br /><br />
24: <asp:Button ID="submit" runat="server" Text="Submit"/>
25: div>
26: form>
27: body>
28: html>
2.SetFocusOnError属性，Page.Validators属性
SetFocusOnError属性可以用于强调错误，所有的验证控件都支持这个属性。如果一个验证控件的SetFocusOnError属性为true，当与验证控件相关联的控件验证错误时，会自动关联到这个被验证控件，使它处于焦点状态。
用SetFocusOnError这个属性的强调效果并不明显，如果想真正强调验证错误的控件，可以用Page.Validators属性，这个属性表示页面的验证集合。我们可以利用Page.Validator属性来突出显示每一个验证错误的控件，代码如下：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: void Page_PreRender()
5: {
6: foreach (BaseValidator valControl in Page.Validators)
7: {
8: //通过Page.Validators属性找到验证控件
9: WebControl assControl = (WebControl)Page.FindControl(valControl.ControlToValidate);
10: if (!valControl.IsValid)
11: assControl.BackColor = System.Drawing.Color.Yellow;
12: else
13: assControl.BackColor = System.Drawing.Color.Gray;
14: }
15: }
16: script>
17: <html xmlns="http://www.w3.org/1999/xhtml" >
18: <head id="Head1" runat="server">
19: <title>Show Page.Validatorstitle>
20: head>
21: <body>
22: <form id="form1" runat="server">
23: <div>
24: <asp:Label
25: id="lblFirstName"
26: Text="First Name"
27: AssociatedControlID="txtFirstName"
28: Runat="server" />
29: <br />
30: <asp:TextBox
31: id="txtFirstName"
32: Runat="server" />
33:
34: <asp:RequiredFieldValidator
35: id="reqFirstName"
36: ControlToValidate="txtFirstName"
37: Text="(Required)"
38: EnableClientScript="false"
39: Runat="server" />
40:
41: <br /><br />
42:
43: <asp:Label ID="lblLastName" runat="server" Text="Last Name:">asp:Label>
44: <br />
45: <asp:TextBox ID="txtLastName" runat="server">asp:TextBox>
46: <asp:RequiredFieldValidator
47: ID="reqLastName"
48: runat="server"
49: ControlToValidate="txtLastName"
50: Text="(Required)"
51: EnableClientScript="false">asp:RequiredFieldValidator>
52: <br /><br />
53:
54: <asp:Button
55: id="btnSubmit"
56: Text="Submit"
57: Runat="server" />
58:
59: div>
60: form>
61: body>
62: html>
3.使用验证组ValidationGroup
我们时常看到一些站点的注册表单和登陆表单在一个页面，而我们又需要对这两个表单进行验证。在验证控件中，有ValidationGroup这样一个属性，可以对验证控件进行分组，给那些验证登录的控件分一组，给用于注册的控件分一组，这样也只需要一个表单。
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: ///
5: /// 登录
6: ///
7: ///
8: ///
9: void btnLogin_Click(Object sender, EventArgs e)
10: {
11: if (Page.IsValid)
12: this.lblLoginResult.Text = "Log in Successful!";
13: }
14:
15: ///
16: /// 注册
17: ///
18: ///
19: ///
20: void btnRegister_Click(Object sender, EventArgs e)
21: {
22: if (Page.IsValid)
23: this.lblRegisterResult.Text = "Registration Sucessful!";
24: }
25: script>
26: <html xmlns="http://www.w3.org/1999/xhtml" >
27: <head id="Head1" runat="server">
28: <title>Show Validation Grouptitle>
29: <style type="text/css">
30: html
31: {
32: background-color: sliver;
33: font-family:Arial, Helvetica, sans-serif;
34: font-size: 12px;
35: color: #333;
36: }
37: .column
38: {
39: float: left;
40: width: 300px;
41: height: 300px;
42: margin-left: 100px;
43: background: white;
44: border: 1px solid #666;
45: padding: 10px;
46: }
47: input
48: {
49: border: 1px solid #ccc;
50: padding: 3px;
51: }
52: style>
53: head>
54: <body>
55: <form id="form1" runat="server">
56: <div class="column">
57: <fieldset>
58: <legend>Loginlegend>
59: <p>Please log in to our Website.p>
60: <asp:Label ID="lblUserName" runat="server" Text="User Name:" AssociatedControlID="txtUserName">asp:Label>
61: <br />
62: <asp:TextBox ID="txtUserName" runat="server">asp:TextBox>
63:
64: <asp:RequiredFieldValidator
65: ID="reqUserName"
66: runat="server"
67: ControlToValidate="txtUserName"
68: Text="(required)"
69: ValidationGroup="LoginGroup">asp:RequiredFieldValidator>
70: <br /><br />
71:
72: <asp:Label ID="lblPassword" runat="server" Text="Password:" AssociatedControlID="txtPassword">asp:Label>
73: <br />
74: <asp:TextBox ID="txtPassword" runat="server" ValidationGroup="LoginGroup">asp:TextBox>
75:
76: <asp:RequiredFieldValidator
77: ID="reqPassword"
78: runat="server"
79: ControlToValidate="txtPassword"
80: Text="(required)"
81: ValidationGroup="LoginGroup">asp:RequiredFieldValidator>
82: <br /><br />
83:
84: <asp:Button ID="btnLogin" runat="server" Text="Login" ValidationGroup="LoginGroup" OnClick="btnLogin_Click"/>
85: fieldset>
86: <asp:Label ID="lblLoginResult" runat="server">asp:Label>
87: div>
88:
89: <div class="column">
90: <fieldset>
91: <legend>Registerlegend>
92: <p>
93: If you do not have a User Name, please
94: register at our Website.
95: p>
96: <asp:Label ID="lblFirstName" runat="server" Text="First Name:" AssociatedControlID="txtFirstName">asp:Label>
97: <br />
98: <asp:TextBox ID="txtFirstName" runat="server">asp:TextBox>
99:
100: <asp:RequiredFieldValidator
101: ID="reqFirstName"
102: runat="server"
103: ErrorMessage="RequiredFieldValidator"
104: ControlToValidate="txtFirstName"
105: Text="(required)"
106: ValidationGroup="RegisterGroup">asp:RequiredFieldValidator>
107: <br /><br />
108:
109: <asp:Label ID="lblLastName" runat="server" Text="Last Name:" AssociatedControlID="txtLastName">asp:Label>
110: <br />
111: <asp:TextBox ID="txtLastName" runat="server">asp:TextBox>
112:
113: <asp:RequiredFieldValidator
114: ID="reqLastName"
115: runat="server"
116: ErrorMessage="RequiredFieldValidator"
117: ControlToValidate="txtLastName"
118: Text="(required)"
119: ValidationGroup="RegisterGroup">asp:RequiredFieldValidator>
120: <br /><br />
121:
122: <asp:Button ID="btnRegister" runat="server" Text="Register" ValidationGroup="RegisterGroup" OnClick="btnRegister_Click"/>
123: fieldset>
124: <asp:Label ID="lblRegisterResult" runat="server">asp:Label>
125: div>
126: form>
127: body>
128: html>
上面的代码中，注意两个组，虽然TextBox也有ValidationGroup属性，但是我们不必为TextBox也设置ValidationGroup，只需为验证控件和按钮设置验证组就可以了。在分了验证组以后，两个表单的行为互不干涉。
4. 禁用验证
所有的按钮控件Button, ImageButton, LinkButton都有一个CauseValidation属性，如果设置这个按钮的CauseValidation属性为false，那么当点击这个按钮时将绕过页面中的所有验证。
下面的代码中，采用一个取消按钮，当点击它时，不对表单进行验证，而是重定向到Default页面
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: void btnCancel_Click(Object sender, EventArgs e)
5: {
6: Response.Redirect("~/Default.aspx");
7: }
8: script>
9: <html xmlns="http://www.w3.org/1999/xhtml" >
10: <head id="Head1" runat="server">
11: <title>Show Disable Validationtitle>
12: head>
13: <body>
14: <form id="form1" runat="server">
15: <div>
16:
17: <asp:Label ID="lblFirstName" runat="server" Text="First Name:" AssociatedControlID="txtFirstName">asp:Label>
18: <br />
19: <asp:TextBox ID="txtFirstName" runat="server">asp:TextBox>
20: <asp:RequiredFieldValidator
21: ID="reqFirstName"
22: runat="server"
23: ControlToValidate="txtFirstName"
24: Text="(required)"
25: >asp:RequiredFieldValidator>
26: <br />
27:
28: <asp:Button ID="btnCancel" runat="server" Text="Cancel" OnClick="btnCancel_Click"/>
29:
30: div>
31: form>
32: body>
33: html>
5.使用RequiredFieldValidator控件
在前面的几个例子当中，已经大量使用了RequireFileldValidator控件，这个控件的作用就是来验证非空字符串。RequireFieldValidator控件还有一个属性IntialValue，这个属性用来指定除空字符串之外的默认值。例如，用RequireFieldValidator控件来验证DropDownList控件。
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: void btnSubmit_Click(Object sender, EventArgs e)
5: {
6: if (Page.IsValid)
7: this.lblResult.Text = this.dropFavoriteColor.SelectedValue;//如果页面验证通过，显示用户选择的结果
8: }
9: script>
10: <html xmlns="http://www.w3.org/1999/xhtml" >
11: <head id="Head1" runat="server">
12: <title>title>
13: head>
14: <body>
15: <form id="form1" runat="server">
16: <div>
17:
18: <asp:Label ID="lblFavoriteColor" runat="server" Text="Favorite Color:">asp:Label>
19: <br />
20: <asp:DropDownList ID="dropFavoriteColor" runat="server">
21: <asp:ListItem Text="Select Color" Value="none">asp:ListItem>
22: <asp:ListItem Text="Red" Value="Red">asp:ListItem>
23: <asp:ListItem Text="Green" Value="Green">asp:ListItem>
24: <asp:ListItem Text="Blue" Value="Blue">asp:ListItem>
25: asp:DropDownList>
26:
27: <asp:RequiredFieldValidator
28: ID="reqFavoriteColor"
29: runat="server"
30: Text="(required)"
31: InitialValue="none"
32: ControlToValidate="dropFavoriteColor"
33: >asp:RequiredFieldValidator>
34: <br />
35: <asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click"/>
36: <hr />
37: <asp:Label ID="lblResult" runat="server">asp:Label>
38:
39: div>
40: form>
41: body>
42: html>
6. 使用RangeValidator控件
RangeValidator控件用于验证表单的值是否位于某个范围之间，所以要为RangeValidator指定一个最小值和最大值。使用这个控件，必须得设置5个属性：
■ControlToValidate——要验证的控件
■Text——验证失败时的错误信息
■MinimumValue——最小值
■MaximumValue——最大值
■Type——所执行的比较类型：Type, Integer, Double, Date, Currency
下面的代码演示了在文本框中输入年龄时，必须输入5-100之间的数值。
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: script>
5: <html xmlns="http://www.w3.org/1999/xhtml" >
6: <head id="Head1" runat="server">
7: <title>Show RangeValidatortitle>
8: head>
9: <body>
10: <form id="form1" runat="server">
11: <div>
12: <asp:Label ID="lblAge" runat="server" Text="Age:" AssociatedControlID="txtAge">asp:Label>
13: <br />
14: <asp:TextBox ID="txtAge" runat="server">asp:TextBox>
15:
16: <asp:RequiredFieldValidator
17: ID="reqFieldAge"
18: runat="server"
19: Display="Dynamic"
20: ControlToValidate="txtAge"
21: Text="(Required)">asp:RequiredFieldValidator>
22:
23:
24: <asp:RangeValidator
25: ID="reqRangeAge"
26: runat="server"
27: Display="Dynamic"
28: Type="Integer"
29: MinimumValue="5"
30: MaximumValue="100"
31: ControlToValidate="txtAge"
32: Text="(Invalid Age)">asp:RangeValidator>
33: <br /><br />
34: <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
35:
36: div>
37: form>
38: body>
39: html>
7. 使用CompareValidator控件
CompareValidator控件可以执行三种不同类型的验证任务：
■ 验证类型。可以用它验证用户在表单字段中是否输入了正确的数据类型
■ 和固定值比较。和固定值之间的关系有：大于、大于等于、小于、小于等于、等于和不等于
■ 比较两个表单字段的值。比如验证用户在注册时，密码和重复密码是否相同。
CompareValidator6个重要的属性：
■ ControlToValidate——被验证的表单的ID
■ Text——错误时显示的文本
■ Type——比较的数据类型：String, Integer, Double, Date,Currency
■ Operator——所执行的比较类型：DataTypeCheck, Equal, GreaterThan, GreaterThanEqual, LessThan, LessThanEqual, NotEqual
■ ValueToCompare——所比较的固定值
■ ControlToCompare——所比较的控件的ID
验证数据类型代码清单：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: script>
5: <html xmlns="http://www.w3.org/1999/xhtml" >
6: <head id="Head1" runat="server">
7: <title>Shoe Data Type Checktitle>
8: head>
9: <body>
10: <form id="form1" runat="server">
11: <div>
12: <asp:Label ID="lblBirthDate" runat="server" Text="Birth Date:" AssociatedControlID="txtBirthDate">asp:Label>
13: <asp:TextBox ID="txtBirthDate" runat="server">asp:TextBox>
14:
22: <asp:CompareValidator
23: runat="server"
24: ID="cmpBirthDate"
25: ControlToValidate="txtBirthDate"
26: Type="Date"
27: Operator="DataTypeCheck"
28: Text="(Invalid Date)">asp:CompareValidator>
29: <br /><br />
30: <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
31: div>
32: form>
33: body>
34: html>
和固定值比较代码清单：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: void Page_Load()
5: {
6: if(!Page.IsPostBack)
7: cmpDate.ValueToCompare = DateTime.Now.ToString("d");//获取当前时间，以当前时间作为比较值，在点击按钮时获取。
8: }
9: script>
10: <html xmlns="http://www.w3.org/1999/xhtml" >
11: <head id="Head1" runat="server">
12: <title>Show Fixed Valuetitle>
13: head>
14: <body>
15: <form id="form1" runat="server">
16: <div>
17: <asp:Label ID="lblDate" runat="server" Text="Date:" AssociatedControlID="txtDate">asp:Label>
18: <asp:TextBox ID="txtDate" runat="server">asp:TextBox>
19:
20: <asp:CompareValidator
21: ID="cmpDate"
22: runat="server"
23: ControlToValidate="txtDate"
24: Operator="GreaterThan"
25: Type="Date"
26: Text="(Date must be greater than now)">asp:CompareValidator>
27: <br /><br />
28: <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
29:
30: div>
31: form>
32: body>
33: html>
两个表单字段进行对比，代码清单：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: script>
5: <html xmlns="http://www.w3.org/1999/xhtml" >
6: <head id="Head1" runat="server">
7: <title>Show Compare Valuestitle>
8: head>
9: <body>
10: <form id="form1" runat="server">
11: <div>
12:
13: <asp:Label ID="lblStartDate" runat="server" Text="Start Date:" AssociatedControlID="txtStartDate">asp:Label>
14: <asp:TextBox ID="txtStartDate" runat="server">asp:TextBox>
15: <br />
16: <asp:Label ID="lblEndDate" runat="server" Text="End Date:" AssociatedControlID="txtEndDate">asp:Label>
17: <asp:TextBox ID="txtEndDate" runat="server">asp:TextBox>
18: <asp:CompareValidator
19: ID="cmpDate"
20: runat="server"
21: ControlToValidate="txtEndDate"
22: ControlToCompare="txtStartDate"
23: Operator="GreaterThan"
24: Type="Date"
25: Text="(End date must be greater than start date)">asp:CompareValidator>
26: <br /><br />
27: <asp:Button runat="server" ID="btnSubmit" Text="Submit"/>
28: div>
29: form>
30: body>
31: html>
8. 使用RegularExpressionValidator控件
使用这个控件，是用正则表达式来对表单进行验证，如果你比较熟悉正则表达式，那在对表单验证时将会非常有用。即使你不熟悉正则表达式，通过www.google.com.hk可以很容易找到常用的正则表达式。如果想快速入门正则表达式，可以看看这里：正则表达式30分钟入门教程。
下面的代码是一个简单的验证Email格式的例子：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: script>
5: <html xmlns="http://www.w3.org/1999/xhtml" >
6: <head id="Head1" runat="server">
7: <title>Show RegularExpressionValidatortitle>
8: head>
9: <body>
10: <form id="form1" runat="server">
11: <div>
12: <asp:Label ID="lblEmail" runat="server" Text="Email:" AssociatedControlID="txtEmail">asp:Label>
13: <asp:TextBox ID="txtEmail" runat="server">asp:TextBox>
14: <asp:RegularExpressionValidator
15: ID="reqEmail"
16: runat="server"
17: ControlToValidate="txtEmail"
18: Text="(Invalid Email)"
19: ValidationExpression="\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*">asp:RegularExpressionValidator>
20: <br /><br />
21: <asp:Button runat="server" ID="btnSubmit" Text="Submit"/>
22: div>
23: form>
24: body>
25: html>
9.使用CustomValidator控件
如果前面的一些验证控件不能够满足你的需要，而你又不愿意使用复杂的正则表达式去验证表单，你可以考虑使用CustomValidator控件，它可能会帮你解决掉一些问题。
CustomValidator控件有三个重要的属性：
■ ControlToValidate
■ Text
■ ClientValidationFunction——这个属性关联一个客户端的javascript函数，可以调用这个函数来对表单进行验证。
CustomValidator控件还有一个服务器端的事件：
■ ServerValidate——CustomValidator控件执行验证时触发该事件。
假设想验证输入表单字段的长度，比如用户评论不得少于5个字符：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: //传给ServerValidate事件的第二个参数是ServerValidateEventArgs类的一个实例
5: protected void valComments_ServerValidate(object source, ServerValidateEventArgs args)
6: {
7:
8: if (args.Value.Length < 5)
9: args.IsValid = false;
10: else
11: args.IsValid = true;
12: }
13: script>
14: <html xmlns="http://www.w3.org/1999/xhtml" >
15: <head id="Head1" runat="server">
16: <title>Show CustomValidatortitle>
17: head>
18: <body>
19: <form id="form1" runat="server">
20: <div>
21: <asp:Label ID="lblComments" runat="server" Text="Comments:" AssociatedControlID="txtComments">asp:Label>
22: <asp:TextBox ID="txtComments" runat="server" Columns="30" Rows="5" TextMode="MultiLine">asp:TextBox>
23: <asp:CustomValidator
24: ID="valComments"
25: runat="server"
26: ControlToValidate="txtComments"
27: Text="(Comments must more than 5 characters)" OnServerValidate="valComments_ServerValidate">asp:CustomValidator>
28: <br /><br />
29: <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
30:
31: div>
32: form>
33: body>
34: html>
ServerValidateEventArgs类有三个属性：
■ Value——被验证的表单字段的值
■ IsValid——验证成功或者失败
■ ValidateEmptyText——表示所验证的表单字段没有值时是否进行验证。如果为true，这个属性也能够验证表单字段是否非空。
ValidateEmptyText的一个例子，检验产品码必须为4个字符：
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4:
5: //如果没有设置ValidateEmptyText="true"这个属性，在表单字段为空的情况下，验证仍然是通过的
6: protected void valProductCode_ServerValidate(object source, ServerValidateEventArgs args)
7: {
8: if (args.Value.Length == 4)
9: args.IsValid = true;
10: else
11: args.IsValid = false;
12: }
13: script>
14: <html xmlns="http://www.w3.org/1999/xhtml" >
15: <head id="Head1" runat="server">
16: <title>Show Validate Empty Texttitle>
17: head>
18: <body>
19: <form id="form1" runat="server">
20: <div>
21: <asp:Label ID="lblProductCode" runat="server" Text="Product Code:" AssociatedControlID="txtProductCode">asp:Label>
22: <asp:TextBox ID="txtProductCode" runat="server">asp:TextBox>
23:
24: <asp:CustomValidator
25: runat="server"
26: ID="valProductCode"
27: ValidateEmptyText="true"
28: ControlToValidate="txtProductCode"
29: Text="(Product code must be 4 characters)"
30: OnServerValidate="valProductCode_ServerValidate">asp:CustomValidator>
31: <br /><br />
32: <asp:Button ID="btnSubmit" runat="server" Text="Submit" />
33:
34: div>
35: form>
36: body>
37: html>
ServerValidate事件是一个服务端事件，只有在页面回传以后，才会执行这个事件进行验证，如果想要通过客户端进行验证，那就要用到前面提到的一个重要的属性ClientValidationFunction，采用客户端的javascript函数也能进行验证。
1: <%@ Page Language="C#"%>
2: DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3: <script runat="server">
4: //执行服务端验证
5: protected void valComments_ServerValidate(object source, ServerValidateEventArgs args)
6: {
7: if (args.Value.Length < 5)
8: args.IsValid = false;
9: else
10: args.IsValid = true;
11: }
12: script>
13: "http://www.w3.org/1999/xhtml" >
14: "Head1" runat="server">
15:Show CustomValidator with JavaScript
16: