Image Verification Code Technology

Establish general functional Class Common.cs

Add a function in this class to generate a random string and convert the output of a string to a picture

The contents are as follows:

Using System;
Using System.Collections.Generic;
Using System.Linq;
Using System.Web;
Using System.Web.UI;
Using System.Web.UI.WebControls;
Using System.Drawing;
Using System.IO;
Namespace Cartoon
{


public class Common
{
Gets a random string
public static string Getrandom (int n)
{
String str = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghizklmnopqrstuvwxyz1234567890";
Random random = new random ();
Generate n-bit random numbers
string result = String. Empty;
for (int i = 1; I <= n; i++)
{
Result + = Str[random. Next (0, str. LENGTH-1)]. ToString ();
}
return result;

//String conversion picture
public static void DisplayImage (String str)
{
　　　　　　Use a cookie or session pass value to verify that the verification code
//session
httpcontext.current.session["code" = str;
Cookies
system.web.httpcontext.current.response.cookies["code"). Value = str; 　　　　　　
//Create a picture area set width and height
Bitmap image = new Bitmap;
　　　　　　Gets the area of the image where it is easy to add an element
Graphics g = graphics.fromimage (image);
　　　　　　Set the picture background to white
G.clear (color.white);
　　　　　　Draw lines to construct some blind spots, meaning that the picture is not clearly displayed
random random = new random ();
for (int i = 0; i < i++)
{
int x1 = random. Next (image. Width);
int y1 = random. Next (image. Height);
int x2 = random. Next (image. Width);
int y2 = random. Next (image. Height);
G.drawline (New Pen (color.silver), x1, y1, x2, y2);
}

Define font objects, set font size

Font font = new Font ("Blackbody", 12);
Defining brush Colors
SolidBrush brush = new SolidBrush (color.blueviolet);
Defines the position coordinate point of the brush write information for the upper-left corner (0,0) point
PointF point = new PointF (2, 2);
Write the string into the picture
g.DrawString (str, font, brush, point);
Draw a border for a picture
G.drawrectangle (New Pen (Color.silver), 0, 0, image. Width-1, image. HEIGHT-1);
Generates a memory stream object for easy storage and output of pictures
MemoryStream ms = new MemoryStream ();
Save the drawn picture to the memory stream in MS
Image. Save (MS, SYSTEM.DRAWING.IMAGING.IMAGEFORMAT.GIF);
Output binary picture stream
HttpContext.Current.Response.BinaryWrite (Ms. ToArray ());



}
}

}

Verification of landing Page:

protected void Jll_click (object sender, EventArgs e)
{
String code = request.form["Check"];
Using cookies to determine
if (Code = = system.web.httpcontext.current.request.cookies["code"). Value)
Use session to determine
if (Code = = session["code"). ToString ())
{
Response.Write ("<script>alert (' right! ') </script> ");
}
Else
{
Response.Write ("<script>alert (' false! ') </script> ");
}
}

Image Verification Code Technology