C # Generate verification code

When doing a login, it is usually necessary to bring a verification code, which is called on the ASPX page:

<input type= "text" id= "Txtcode" style= "WIDTH:35PX;HEIGHT:22PX; padding-top:3px; "maxlength=" 4 "/>
Style= "width:50px; Cursor:pointer; height:22px; "/>
<a style= "color: #528311; Cursor:pointer; font-size:12px; "Onclick=" Getsessionimg ($ (' #logingImg ')); " > Change a new </a>

<script type= "Text/javascript" >

Toggle Call

function Getsessionimg (objthis) {
$ ("#txtCode"). Val ("");
$ (objthis). attr ("src", "*/load_img/ajax-loader_05.gif");//Loading thumbnails
$ (objthis). attr ("src", "*/checkcode.aspx?id=" + math.random ());
$ ("#txtCode"). focus ();
}

</script>

Post code in Checkcode.aspx:

Reference namespaces: Using System.Drawing;

Load Call

protected void Page_Load (object sender, EventArgs e)
{
if (! IsPostBack)
{
This. Createcheckcodeimage (Generatecheckcode ());
}
}

<summary>
Generate a 4-digit verification Code
</summary>
private String Generatecheckcode ()
{
int number;
char code;
String Chkcode= String.Empty;
System.Random random = new Random ();
for (int i = 0; i < 4; i++)
{//randomly generated
Number = random. Next ();
if (number% 2 = = 0)
Code = (char) (' 0 ' + (char) (number% 10));//divide by 10 to take remainder (random numbers like 876 is 6) 00-09 and cast
Else
Code = (char) (' A ' + (char) number% 26);//divided by 26 to get the remainder of the result count and then the number of a back is the resulting value such as number=28, that is code=c
chkcode+= code. ToString ();
}
if (Checkcode.trim (). Equals ("") | | Checkcode.trim (). Length! = 4)
{
Generatecheckcode ();//Not enough four bits to build
}
Else
{
session["User_code"] =chkcode;//save session to verify that the login matches
}
return chkcode;
}

<summary>

Output Verification Code

</summary>

private void Createcheckcodeimage (string checkcode)

{

if (Checkcode = = NULL | | Checkcode.trim () = = String.Empty)

{

Return

}

System.Drawing.Bitmap image = new Bitmap ((int) math.ceiling ((Checkcode.length * 12.5)), 22); Returns the smallest integer greater than or equal to the specified number.

Graphics g = graphics.fromimage (image);//Create Image Object

try {

Random random = new random ();

G.clear (Color.White);

for (int i = 0; i <; 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.greenyellow), x1, y1, x2, y2); Draws a line that connects two points specified by a coordinate pair

}

Font

Font font = new System.Drawing.Font ("Verdana", A, (System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic));

Pen Brush

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);

Draw the foreground noise point of the picture

for (int i = 0; i <; i++)

{

int x = random. Next (image. Width);

int y = random. Next (image. Height);

Image. SetPixel (x, Y, Color.FromArgb (random.   Next ())); To draw a point of color in a line of coordinates

}

Draw the border line of a picture

G.drawrectangle (New Pen (Color.bisque), 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 ());//writes a binary string to the HTTP output stream

} catch (Exception ex) {

Console.Write (ex. Message);

} finally {

Close or release unmanaged resources such as files, streams, and handles persisted by instances of classes that implement this interface

G.dispose ();

Image. Dispose ();

}

}

C # Generate verification code