ASP. NET custom verification code control

Recently I wrote a custom verification code control to share it with you.

Procedure

1 --- create an Asp.net website

2 --- Add a new project and select a class library

3 --- create two classes

3.1 -- custom control class (webcontrol derived class)

Using system;
Using system. Collections. Generic;
Using system. componentmodel;
Using system. LINQ;
Using system. text;
Using system. Web;
Using system. Web. UI;
Using system. Web. UI. webcontrols;

Namespace authcode
{
[Toolboxdata ("<{ 0}: authcode runat = Server> </{0}: authcode>")]
Public class authcode: webcontrol
{
/// <Summary>
/// Obtain the verification code value
/// </Summary>
/// <Returns> Verification Code </returns>
Public String getvalue ()
{
Return httpcontext. Current. session ["value"]. tostring ();
}
[Bindable (true)]
[Category ("appearance")]
[Description ("Verification Code character length")]
[Defaultvalue ("SS")]
[Localizable (true)]
// Length
Internal static int mysize;

Public int mysize
{< br> get {return authcode. mysize ;}< br> set
{< br> authcode. mysize = value;

}< BR >}< br>

Public authcode ()
: Base (htmltextwritertag. IMG) // rewrite the structure of the parent class (HTML tag of the output stream)
{}< br> protected override void addattributestorender (htmltextwriter writer)
{< br> base. addattributestorender (writer); // Add the attributes and styles of the HTML tag to be output to the specified htmltextwriter.
writer. addstyleattribute (htmltextwriterstyle. cursor, "Pointer"); // Add a style

/**-
* onclick event of the image "This. src = 'verifyimg. JD? Id = '+ math. Random () "
* a new image Request Path (verifyimg. JD? Id = '+ math. the random () parameter is only
* tells the browser that this is a new request and is processed by ihttphander to generate a new image ID, which has no actual meaning (create a new request)
*-**/
writer. addattribute ("onclick", "this. src = 'img. JD? Id = '+ math. Random () "); // Add JS verifyimg. JD

Writer. addattribute (htmltextwriterattribute. SRC, "IMG. JD ");
Writer. addattribute ("Alt", "click to refresh ");
}

}
}
 

3.2 -- create a processing class (the ihttphandler and irequiressessionstate interfaces must be implemented)

Using system;
Using system. Collections. Generic;
Using system. LINQ;
Using system. text;
Using system. Web;
Using system. Web. UI. webcontrols;
Using system. Web. UI;
Using system. Web. sessionstate;
Using system. drawing;
Using system. IO;

Namespace authcode
{
Public class authcodehttphander: ihttphandler, irequiressessionstate
{
/// <Summary>
/// Return verification code characters
/// </Summary>
/// <Param name = "codecount"> Verification code length </param>
/// <Returns> </returns>
Private string getrandomnumberstring (INT codecount)
{
String strchoice = "2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F, G, H, J, K, L, M, N, P, q, R, S, T, U, V, W, X, Y, Z ";
String [] strresult = strchoice. Split (New char [] {','});
String strreturn = "";
Random RND = new random ();
For (INT I = 0; I <codecount; I ++)
{
Int J = RND. Next (strresult. Length); // the random number cannot exceed the length of the array.
Strreturn = strreturn + strresult [J]. tostring ();
}
Return strreturn;
}

Private color getcolor ()
{
Return color. Black;
}
Private bitmap createimage (string str_authcode)
{
/* ----------------------------- Draw the image style ------------------------------------*/

Int width = str_authcode.length * 21;
Int Height = 30;
Random rad = new random ();
Bitmap BMP = new Bitmap (width, height );
Graphics GRP = graphics. fromimage (BMP); // draw the image
GRP. Clear (color. yellowgreen); // fill in the background color of BMP.
GRP. drawrectangle (new pen (color. Red, 1), 0, 0, width-1, height-1); // draw a border
Int num = width * height;
For (INT I = 0; I <num; I ++) // draw a colored dot on the specified coordinate of the image
{
Int x = rad. Next (width );
Int y = rad. Next (height );
Int r = rad. Next (255 );
Int G = rad. Next (255 );
Int B = rad. Next (255 );
Color c = color. fromargb (R, G, B );
BMP. setpixel (X, Y, c); // draw colored dots on the specified coordinates of the image.
}

/* -------------------------- Draw a string in the image ------------------------------------*/

Font F = new font ("", 20, fontstyle. Bold); // define the font
Brush BR = new solidbrush (color. Black); // defines the color of the paint brush and the color of the font.
For (INT I = 0; I <str_authcode.length; I ++)
{
String S = str_authcode.substring (I, 1); // draw a single image
Point P = new point (I * 20 + rad. Next (3), Rad. Next (3) + 1); // the position where the font appears (coordinates)
GRP. drawstring (S, F, BR, P); // draw a string
}
GRP. Dispose ();
Return BMP; // return

}

/// <Summary>
/// Whether remote HTTP requests can be processed
/// </Summary>
Public bool isreusable
{
Get {return true ;}
}

/// <Summary>
/// Send the verification code image to the Web browser
/// </Summary>
/// <Param name = "context"> </param>
Public void processrequest (httpcontext context)
{
Int size = authcode. mysize; // int32.parse (string) Context. session ["size"]);
Memorystream MS = new memorystream (); // creates a memory stream (the initial length is 0 automatically expanded)
String numstr = getrandomnumberstring (size); // The Verification Code character.
Context. session. Add ("value", numstr); // Save the verification code character to the session.
Bitmap thebitmap = createimage (numstr); // obtain the verification code Image
Thebitmap. Save (MS, system. Drawing. imaging. imageformat. JPEG); // write bitmap into memory stream
Context. response. clearcontent (); // clear all content output in the buffer
Context. response. contenttype = "image/JPEG"; // you need to modify the HTTP header to output the image information.
Context. response. binarywrite (Ms. toarray (); // write the memory stream to the HTTP output stream
Thebitmap. Dispose (); // release resources
Ms. Close (); // release resources
Ms. Dispose (); // release resources
Context. response. End ();
}

}
}
 

4 --- generate the solution and class library, open the web form, and click the toolbar.

 

5 -- drag to the web form

<% @ Page Language = "C #" autoeventwireup = "true" codefile = "default. aspx. cs" inherits = "_ default" %>

<% @ Register Assembly = "authcode" namespace = "authcode" tagprefix = "PC3" %>

<〈! Doctype HTML public "-// W3C // dtd xhtml 1.0 transitional // en ""Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<HTML xmlns ="Http://www.w3.org/1999/xhtml">
<Head runat = "server">
<Title> No title page </title>
</Head>
<Body>
<Form ID = "form1" runat = "server">
<Div>
<C0: authcode id = "authcode1" runat = "server" mysize = "5"/>
</Div>
</Form>
</Body>
</Html>

Set Verification Code character Length

6 -- add a node in the webconfig File

<System. Web>
<Httphandlers>
<Add verb = "*" Path = "*. JD" type = "authcode. authcodehttphander"/>
</Httphandlers>
</System. Web>

7 -- View in the browser

Click to refresh

8 -- "this. authcode1.getvalue () to obtain the verification code

End

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