c# 验证码实现代码
using System;using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Linq;
using System.Web;
namespace Web.Admin.handler
{
/// <summary>
/// ValidateCode 的摘要说明
/// </summary>
public class ValidateCode : IHttpHandler, System.Web.SessionState.IRequiresSessionState
{
public void Proce***equest(HttpContext context)
{
//创建验证码
string code = CreateValidateCode(5);
//把验证码写到响应流里面去
CreateValidateGraphic(code, context);
//保存到session中
context.Session["code"] = code;
}
/// <summary>
/// 生成验证码
/// </summary>
/// <param name="length">指定验证码的长度</param>
/// <returns></returns>
protected string CreateValidateCode(int length)
{
int[] randMembers = new int;
int[] validateNums = new int;
string validateNumberStr = "";
//生成起始序列值
int seekSeek = unchecked((int)DateTime.Now.Ticks);
Random seekRand = new Random(seekSeek);
int beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
int[] seeks = new int;
for (int i = 0; i < length; i++)
{
beginSeek += 10000;
seeks = beginSeek;
}
//生成随机数字
for (int i = 0; i < length; i++)
{
Random rand = new Random(seeks);
int pownum = 1 * (int)Math.Pow(10, length);
randMembers = rand.Next(pownum, Int32.MaxValue);
}
//抽取随机数字
for (int i = 0; i < length; i++)
{
string numStr = randMembers.ToString();
int numLength = numStr.Length;
Random rand = new Random();
int numPosition = rand.Next(0, numLength - 1);
validateNums = Int32.Parse(numStr.Substring(numPosition, 1));
}
//生成验证码
for (int i = 0; i < length; i++)
{
validateNumberStr += validateNums.ToString();
}
return validateNumberStr;
}
/// <summary>
/// 创建验证码的图片，把验证码写到响应流里面去。
/// </summary>
/// <param name="containsPage">要输出到的page对象</param>
/// <param name="validateNum">验证码</param>
public void CreateValidateGraphic(string validateCode, HttpContext context)
{
Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 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);
//画图片的干扰线
for (int 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 Font("Arial", 12, (FontStyle.Bold | FontStyle.Italic));
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(validateCode, font, brush, 3, 2);
//画图片的前景干扰点
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);
//保存图片数据
MemoryStream stream = new MemoryStream();
image.Save(stream, ImageFormat.Jpeg);
//输出图片流
context.Response.Clear();//把之前Response的字节数组清空。
context.Response.ContentType = "image/jpeg";
context.Response.BinaryWrite(stream.ToArray());
}
finally
{
g.Dispose();
image.Dispose();
}
}
public bool IsReusable
{
get
{
return false;
}
}
}
}
文档来源：51CTO技术博客https://blog.51cto.com/u_15309652/3156397
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