c#生成验证码的方法

新建一个WaterMark.ASHX文件，将如下代码Copy进去

<%@ WebHandler Language="C#" Class="WaterMark" %>

using System;

using System.Web;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Web.SessionState;

public class WaterMark : IHttpHandler, IRequiresSessionState // 要使用session必须实现该接口,记得要导入System.Web.SessionState命名空间

{

public void ProcessRequest(HttpContext context)

{

string checkCode = GenCode(5); // 产生5位随机字符

context.Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证

System.Drawing.Bitmap image = new System.Drawing.Bitmap(70, 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

int i;

for (i = 0; i < 25; 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.Silver), 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

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);

context.Response.ClearContent();

context.Response.ContentType = "image/Gif";

context.Response.BinaryWrite(ms.ToArray());

}

finally

{

g.Dispose();

image.Dispose();

}

}

///

/// 产生随机字符串

///

/// 随机出几个字符

/// 随机出的字符串

private string GenCode(int num)

{

string str = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";//"

char[] chastr = str.ToCharArray();

// string[] source ={ "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "#", "$", "%", "&", "@" };

string code = "";

Random rd = new Random();

int i;

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

{

//code += source[rd.Next(0, source.Length)];

code += str.Substring(rd.Next(0, str.Length), 1);

}

return code;

}

public bool IsReusable

{

get

{

return false;

}