ASP. NET image verification code learning!

1. Create a New Validate. aspx and write the code in Validate. aspx. cs:

Using System;
Using System. Collections;
Using System. ComponentModel;
Using System. Data;
Using System. Web;
Using System. Drawing;
Using System. Web. SessionState;
Using System. Web. UI;
Using System. Web. UI. WebControls;
Using System. Web. UI. HtmlControls;
Using System. Drawing. Imaging;
Using System. IO;

 

Public partial class Validate: System. Web. UI. Page
{
Protected void Page_Load (object sender, EventArgs e)
{
This. CreateCheckCodeImage (RndNum ());

}
Private string RndNum ()
{
Int number;
Char code;
String checkCode = String. Empty;

System. Random random = new Random ();

For (int I = 0; I <4; I ++)
{
Number = random. Next ();
If (number % 2 = 0)
Code = (char) ('0' + (char) (number % 10 ));
Else
Code = (char) ('A' + (char) (number % 26 ));
CheckCode + = code. ToString ();
}

Session ["CheckCode"] = checkCode;
Return checkCode;
}
Private void CreateCheckCodeImage (string checkCode)
{
If (checkCode = null | checkCode. Trim () = String. Empty)
Return;
System. Drawing. Bitmap image = new System. Drawing. Bitmap (int) Math. Ceiling (checkCode. Length * 12.5), 22 );
Graphics g = Graphics. FromImage (image );
Try
{

Random random = new Random ();

G. Clear (Color. White );

For (int I = 0; I <25; I ++)
{
Int x1 = random. Next (image. Width );
Int x2 = random. Next (image. Width );
Int y1 = random. Next (image. Height );
Int y2 = random. Next (image. Height );
G. DrawLine (new Pen (Color. Silver), x1, y1, x2, y2 );
}

Font font = new System. Drawing. Font ("Arial", 12, (System. Drawing. FontStyle. Bold | System. Drawing. FontStyle. Italic ));
System. drawing. drawing2D. linearGradientBrush brush = new System. drawing. drawing2D. linearGradientBrush (new Rectangle (0, 0, image. width, image. height), Color. blue, Color. darkRed, 1.2f, true );
G. DrawString (checkCode, font, brush, 2, 2 );

For (int I = 0; I <100; I ++)
{
Int x = random. Next (image. Width );
Int y = random. Next (image. Height );
Image. SetPixel (x, y, Color. FromArgb (random. Next ()));
}
　　　　　　
G. DrawRectangle (new Pen (Color. Silver), 0, 0, image. Width-1, image. Height-1 );
System. IO. MemoryStream MS = new System. IO. MemoryStream ();
Image. Save (MS, System. Drawing. Imaging. ImageFormat. Gif );
Response. ClearContent ();
Response. ContentType = "image/Gif ";
Response. BinaryWrite (ms. ToArray ());
}
Finally
{
G. Dispose ();
Image. Dispose ();
}
}

}

 

2. Add this code on the page you want to add at the front-end: (I assume that the image verification code is added to Login. aspx on the logon page)

Img. src = img. src + '? ';
}
</Script>

 

3. Add the implementation code in the background Login. aspx. cs:

Reference ......

Public partial class Login: System. Web. UI. Page
{
Protected void Page_Load (object sender, EventArgs e)
{

}

　　
Protected void btnLogin_Click (object sender, ImageClickEventArgs e)
{
User user = new User ();
User. LoginId = this.txt _ LoginId. Text. Trim ();
User. LoginPwd = this.txt _ LoginPwd. Text. Trim ();
If (this.txt Code. Text. ToLower () = Session ["CheckCode"]. ToString (). ToLower ())
{
Response. Redirect ("Index. aspx ");

Else
{
Session ["user"] = null;
This. Page. ClientScript. RegisterStartupScript (this. GetType (), "str", "<script> alert (\" Logon Failed !! \ ") </Script> ");
}
}
Else
{
This. Page. ClientScript. RegisterStartupScript (this. GetType (), "str", "<script> alert (\" Incorrect verification code !! \ ") </Script> ");
}

}

　　
Protected void btn_Register_Click (object sender, ImageClickEventArgs e)
{
Response. Redirect ("Register. aspx ");
}
}

 

The final verification code is like this ~~

 

 

Of course, if you want to implement code on other pages, there will be some minor changes, but the basic code is like this ~~

Thanks ~~