Verification code technology is designed to prevent violent cracking, and so on. Now the general website registration and so on provide authentication code function, especially Tencent is a long string. The text refers to someone else's code. There is no need to write again. can read it. But I found two pageload problems during the test. Two sentences can be commented on. The namespaces was modified at the same time. Complete validation instructions are also available:
Using System;
Using System.Collections;
Using System.ComponentModel;
Using System.Data;
Using System.Web;
Using System.Web.SessionState;
Using System.Web.UI;
Using System.Web.UI.WebControls;
Using System.Web.UI.HtmlControls;
Using System.Drawing;
Using System.Drawing.Imaging;
Using System.Drawing.Text;
/**/////<summary>
Page Verification Code Program
Using: Add HTML code to the page
</summary>
public partial class VerifyCode:System.Web.UI.Page
... {
Static string[] Fontitems = new string[] ... {"Arial",
"Helvetica",
"Geneva",
"Sans-serif",
"Verdana"
};
Static brush[] Brushitems = new brush[] ... {Brushes.olivedrab,
Brushes.forestgreen,
Brushes.darkcyan,
Brushes.lightslategray,
Brushes.royalblue,
Brushes.slateblue,
Brushes.darkviolet,
Brushes.mediumvioletred,
Brushes.indianred,
Brushes.firebrick,
Brushes.chocolate,
Brushes.peru,
Brushes.goldenrod
};
Static string[] Brushname = new string[] ... {"Olivedrab",
"Forestgreen",
"Darkcyan",
"Lightslategray",
"Royalblue",
"Slateblue",
"Darkviolet",
"Mediumvioletred",
"Indianred",
"Firebrick",
"Chocolate",
"Peru",
"Goldenrod"
};
private static Color BackColor = Color.White;
private static Pen bordercolor = Pens.darkgray;
private static int Width = 52;
private static int Height = 21;
Private Random _random;
private string _code;
private int _brushnameindex;
Override protected void OnInit (EventArgs e)
... {
//
Codegen:this the call are required by the ASP.net Web Form Designer.
//
InitializeComponent ();
Base. OnInit (e);
}
/**//**//**////<summary>
Required to Designer support-do not modify
The contents is with the Code Editor.
</summary>
private void InitializeComponent ()
... {
This. Load + = new System.EventHandler (this. Page_Load);
}
/**////<summary>
///
</summary>
<param name= "Sender" ></param>
<param name= "E" ></param>
public void Page_Load (object sender, System.EventArgs e)
... {
if (! IsPostBack)
... {
//
Todo:initialize
//
This._random = new Random ();
This._code = Getrandomcode ();
//
Todo:use session["Code"] Save the Verifycode
//
session["code"] = This._code;
//
Todo:output Image
//
This. Setpagenocache ();
This. OnPaint ();
}
}
/**//**//**////<summary>
Set the page not to be cached
</summary>
private void Setpagenocache ()
... {
Response.Buffer = true;
Response.ExpiresAbsolute = System.DateTime.Now.AddSeconds (-1);
Response.Expires = 0;
Response.CacheControl = "No-cache";
Response.appendheader ("Pragma", "No-cache");
}
/**//**//**////<summary>
To get a 4-bit random code
</summary>
<returns></returns>
private String Getrandomcode ()
... {
Return Guid.NewGuid (). ToString (). Substring (0, 4);
}
/**//**//**////<summary>
Randomly take a font
</summary>
<returns></returns>
Private Font GetFont ()
... {
int fontindex = _random. Next (0, fontitems.length);
FontStyle FontStyle = Getfontstyle (_random. Next (0, 2));
return new Font (Fontitems[fontindex], fontstyle);
}
/**//**//**////<summary>
Take the style of a font
</summary>
<param name= "Index" ></param>
<returns></returns>
Private FontStyle getfontstyle (int index)
... {
Switch (index)
... {
Case 0:
return fontstyle.bold;
Case 1:
return fontstyle.italic;
Default
return fontstyle.regular;
}
}
/**//**//**////<summary>
Randomly take a brush
</summary>
<returns></returns>
Private Brush Getbrush ()
... {
int brushindex = _random. Next (0, brushitems.length);
_brushnameindex = Brushindex;
return Brushitems[brushindex];
}
/**//**//**////<summary>
Painting events
</summary>
private void OnPaint ()
... {
Bitmap objbitmap = null;
Graphics g = null;
Try
... {
Objbitmap = new Bitmap (Width, Height);
g = Graphics.fromimage (Objbitmap);
Paint_background (g);
Paint_text (g);
Paint_textstain (OBJBITMAP);
Paint_border (g);
Objbitmap.save (Response.outputstream, imageformat.gif);
Response.ContentType = "Image/gif";
}
Catch... {}
Finally
... {
if (null!= objbitmap)
Objbitmap.dispose ();
if (null!= g)
G.dispose ();
}
}
/**//**//**////<summary>
Painting background color
</summary>
<param name= "G" ></param>
private void Paint_background (Graphics g)
... {
G.clear (BackColor);
}
/**//**//**////<summary>
Painting borders
</summary>
<param name= "G" ></param>
private void Paint_border (Graphics g)
... {
G.drawrectangle (bordercolor, 0, 0, Width-1, Height-1);
}
/**//**//**////<summary>
Painting text
</summary>
<param name= "G" ></param>
private void Paint_text (Graphics g)
... {
g.DrawString (_code, GetFont (), Getbrush (), 3, 1);
}
/**//**//**////<summary>
Drawing text Noise Point
</summary>
<param name= "G" ></param>
private void Paint_textstain (Bitmap b)
... {
for (int n=0; n<30; n++)
... {
int x = _random. Next (Width);
int y = _random. Next (Height);
B.setpixel (x, Y, Color.fromname (brushname[_brushnameindex));
}
}
}
Generally need to provide refresh at the same time (see not clear for another), the code is as follows
<asp:image id= "GetCode" src= "verifycode.aspx" runat= "Server"/> <a "href= ()" > Refresh Verification Code </A>
The above code is to store the verification code in the session, using code to mark. Read the code session["Codes". ToString ();
In use, we only need to compare session["code". ToString () and the text box input string (textboxcode.text) is the same can be judged.
if (session["code"]. ToString (). Trim (). Equals (TextBoxCode.Text.Trim ()))
... {
