AJAX Control Toolkit - NoBot

关于Nobot可以参看NoBot，一下提供一个微软的案例：

 1 <form>   
 2 <asp:ScriptManager ID="ScriptManager1" runat="server" />
 3         <div>
 4         <asp:MultiView ID="MultiView1" runat="server">
 5             <asp:View ID="View1" runat="server">
 6                 <p>Please fill out the form below and submit it:</p>
 7                 <p>
 8                     First Name: <asp:TextBox ID="TextBox1" runat="server" Text="Anonymous" /><br />
 9                     Last Name: <asp:TextBox ID="TextBox2" runat="server" Text="User" />
10                 </p>
11                <asp:Button ID="Button1" runat="server" Text="Submit" />
12             </asp:View>
13             <asp:View ID="View2" runat="server">
14                 <p><b><asp:Label ID="Label1" runat="server" /></b></p>
15                 <br />
16                 <p>Explanation of possible responses:</p>
17                 <ul>
18                     <li><b>Valid</b>: All NoBot tests passed; user appears to be human</li>
19                     <li><b>InvalidBadResponse</b>: An invalid response was provided to the challenge suggesting the challenge script was not run</li>
20                     <li><b>InvalidResponseTooSoon</b>: The postback occurred quickly enough that a human was probably not involved</li>
21                     <li><b>InvalidAddressTooActive</b>: The source IP address has submitted so many responses that a human was probably not involved</li>
22                     <li><b>InvalidBadSession</b>: The ASP.NET session state for this session was unusable</li>
23                     <li><b>InvalidUnknown</b>: An unknown problem occurred</li>
24                 </ul>
25                 <br />
26                 <asp:HyperLink ID="HyperLink" runat="server" Text="Try again" NavigateUrl="~/Default.aspx" />
27                 <br /><br />
28                 <div style="font-size:8pt; background-color:#eeeeee; border-style:dashed; border-width:1pt; padding:3px">
29                     <p>NoBot's user address cache (time IP):</p>
30                     <p><asp:Label ID="Label2" runat="server" /></p>
31                 </div>
32             </asp:View>
33         </asp:MultiView>
34         
35         <ajaxToolkit:NoBot ID="NoBot1" runat="server" OnGenerateChallengeAndResponse="CustomChallengeResponse" />
36     </div>
37     </form>    

　　

 1  protected void Page_Load(object sender, EventArgs e)
 2     {
 3         if (IsPostBack)
 4         {
 5             // Display results view
 6             MultiView1.SetActiveView(View2);
 7             NoBotState state;
 8             Label1.Text = string.Format(
 9                 (NoBot1.IsValid(out state) ?
10                     "Congratulations, \"{1} {2}\", you do not appear to be a bot. (Details: {0})" :
11                     "Rejected; user appears to be a bot. (Details: {0})"),
12                     state.ToString(), TextBox1.Text, TextBox2.Text);
13             StringBuilder sb = new StringBuilder();
14             foreach (KeyValuePair<DateTime, string> kvp in NoBot.GetCopyOfUserAddressCache())
15             {
16                 sb.AppendFormat("{0}: {1}<br />", kvp.Key.ToString("u"), kvp.Value);
17             }
18             Label2.Text = sb.ToString();
19             if (NoBot1.IsValid(out state))
20             {
21                 Label1.BackColor = System.Drawing.Color.White;
22             }
23             else
24             {
25                 Label1.BackColor = System.Drawing.Color.Red;
26             }
27         }
28         else
29         {
30             // Display input view
31             MultiView1.SetActiveView(View1);
32         }
33     }
34 
35     protected void CustomChallengeResponse(object sender, NoBotEventArgs e)
36     {
37         // This is a sample challenge/response implementation that involves
38         // the DOM so as to make the calculation more difficult to thwart.
39         // It adds a randomly sized Panel; the client must calculate the area.
40         Panel p = new Panel();
41         p.ID = "NoBotSamplePanel";
42         Random rand = new Random();
43         p.Width = rand.Next(300);
44         p.Height = rand.Next(200);
45         p.Style.Add(HtmlTextWriterStyle.Visibility, "hidden");
46         p.Style.Add(HtmlTextWriterStyle.Position, "absolute");
47         ((NoBot)sender).Controls.Add(p);
48         e.ChallengeScript = string.Format("var e = document.getElementById('{0}'); e.offsetWidth * e.offsetHeight;", p.ClientID);
49         e.RequiredResponse = (p.Width.Value * p.Height.Value).ToString();
50     }