C#绘制字母和数字混和的验证码 源码

using System;

using System.Data;

using System.Configuration;

using System.Web;

using System.Web.Security;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Web.UI.WebControls.WebParts;

using System.Web.UI.HtmlControls;

using System.Drawing; //添加引用

public partial
class
_Default
: System.Web.UI.Page

{

protected void
Page_Load(object sender,
EventArgs e)

{

CreateCheckCodeImage(GenerateCheckCode());

}

private string
GenerateCheckCode()

{

int number;

char code;

string checkCode =
String.Empty;

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();

}

Response.Cookies.Add(new
HttpCookie("CheckCode", checkCode));

return
checkCode;

}

private void
CreateCheckCodeImage(string checkCode)

{

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

{

//生成随机生成器

Random random =
new Random();

//清空图片背景色

g.Clear(Color.White);

//画图片的背景噪音线

for (int
i = 0; i < 2; 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.Black), x1, y1, x2, y2);

}

Font
font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));

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);

//画图片的前景噪音点

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()));

}

//画图片的边框线

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);

Response.ClearContent();

Response.ContentType = "image/Gif";

Response.BinaryWrite(ms.ToArray());

}

finally

{

g.Dispose();

image.Dispose();

}

}

}