How to generate a verification code Asp.net

Today, I searched the internet for how to generate a Verification Code. There are many examples. I read an article and have a rough understanding of it.

I don't know much about. Net classes, such as bitmap. I can only do it based on others. He uses VB. NET to do this. I can only use C # Instead of VB.net.

Create a web project, and create a web form named GIF. aspx.

Build Method

Private void createpic (string Str)
{
System. Drawing. bitmap BMP;
System. Drawing. Graphics g;
System. Io. memorystream MS;

// I still don't understand why I want to do this. I will take a look at the tutorial later.

Int piclen = Str. length * 12;

BMP = new Bitmap (piclen, 20 );
G = system. Drawing. Graphics. fromimage (BMP );
G. drawstring (STR, (new font ("Arial", 12), (new solidbrush (color. Blue), 1, 1 );

MS = new system. Io. memorystream ();
BMP. Save (MS, imageformat. PNG );
Response. clearcontent ();
Response. contenttype = "image/PNG ";
Response. binarywrite (Ms. toarray ());

G. Dispose ();
BMP. Dispose ();
Response. End ();

}

Create a method to generate random numbers

Private string createrandomiz (int n)
{
System. Random r = new random ();
String STR = ", Q, W, E, R, T, Y, U, I, O, P, A, S, D, f, G, H, J, K, L, Z, X, C, V, B, n, m ";
Char [] A = new char [1];
A [0] = ',';

String [] str1 = Str. Split ();
String temp = "";
For (INT I = 0; I <n; I ++)
{

Temp = temp + str1 [R. Next (35)]. tostring ();

}
Return temp;
}

 

Then you can call it in page_load.
Private void page_load (Object sender, system. eventargs E)
{
String num = This. createrandomiz (4); // generates four random numbers.
Session ["A"] = num; // use session to save
This. createpic (Num );
}

Add an image Web Server Control to webform1 to set the imageurl to gif. aspx.
Drag and Drop a button and a textbox
Write in button

If (this. textbox1.text! = Session ["A"]. tostring ())
{
Response. Write ("error ");
}
Else
{
Response. Write ("OK ");
}

 

This completes. Continue to read the tutorial.