Create a verification code in the ashx file (use session to inherit irequiressessionstate)

[Network reprint] Note:
You must inherit the system. Web. sessionstate. irequiressessionstate interface to read and write sessions!

System. Web. sessionstate Interfaces

Ireadonlysessionstate specifies the target HTTP ProcessingProgramYou only need to have the read permission on the session status value. This is a tag interface and there is no way.
Irequiressessionstate specifies that the target HTTP handler must have read and write access to the session status value. This is a tag interface and there is no way.

 

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Ashx File

 

<% @ Webhandler Language = "C #" class = "checkcode" %>

Using system;
Using system. Web;
Using system. drawing;
Using system. Web. sessionstate;

Public class checkcode: ihttphandler, irequiressessionstate
{

Public void processrequest (httpcontext context)
{
Context. response. contenttype = "text/plain ";
String code = generatecheckcode ();
Context. session ["code"] = code;
This. createcheckcodeimage (Code, context );
}
Private string generatecheckcode ()
{
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 ();
}

Return checkcode;
}

Private void createcheckcodeimage (string checkcode, httpcontext context)
{
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
{
// Generate a random Generator
Random random = new random ();

// Clear the background color of the image
G. Clear (color. White );

// Draw the background noise line of the image
For (INT I = 0; I <5; 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 );

// Foreground noise of the image
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 ()));
}

// Draw the border line of the image
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 );
Context. response. clearcontent ();
Context. response. contenttype = "image/GIF ";
Context. response. binarywrite (Ms. toarray ());
}
Finally
{
G. Dispose ();
Image. Dispose ();
}
}
Public bool isreusable {
Get {
Return false;
}
}

}

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Page Verification

Check whether the verification code is correct
Session ["code"]. tostring () = value of the text box entered by the user