验证码生成 c#

1.验证码生成类

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;
using System.Web.UI.WebControls;

namespace AuthenticationDemo.Common
{
    public class ValidationCodeHelper
    {
        /// <summary>
        /// 创建验证码
        /// </summary>
        /// <param name="codeLength">验证码位数</param>
        /// <returns></returns>
        public string CreateCode(int codeLength)
        {
            // 不要   "0"
            string so = "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,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[] strArr = so.Split(',');
            string code = "";
            Random rand = new Random();
            for (int i = 0; i < codeLength; i++)
            {
                code += strArr[rand.Next(0, strArr.Length)];
            }
            return code;
        }
        /// <summary>
        /// 产生图片
        /// </summary>
        /// <param name="code">验证码</param>
        public byte[] CreateImage(string code)
        {
            Bitmap image = new Bitmap(64, 32);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //随机转动角度 
                //int randAngle = 45;
                //实例随机生成器
                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", 16, (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                //float angle = random.Next(-randAngle,randAngle);
                //g.RotateTransform(angle);
                g.DrawString(code, font, brush, 3, 2);
                //g.RotateTransform(angle);
                //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 ms = new MemoryStream();
                image.Save(ms, ImageFormat.Jpeg);
                //输出图片流
                return ms.ToArray();
            }
            catch (Exception)
            {
                throw;
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }

    }
}

2.后台调用

   public ActionResult GetVCode()
        {
            ValidationCodeHelper vc = new ValidationCodeHelper();
            //验证码
            string code = vc.CreateCode(4);
            Session["vCode"] = code;//保存生成的验证码,提供之后与用户的输入的验证码比较
            byte[] bytes = vc.CreateImage(code);
            return File(bytes, @"image/jpeg");
        }

3.html页面

html代码: 
<img id="vCodeImage" src="@Url.Action("GetVCode","Account")?t=@DateTime.Now.Ticks" alt="验证码图片" title="验证码图片" style="display:inline" />
 <a href="#" onclick="changeOne()">换一张</a>
js代码:

function changeOne() {
var image = document.getElementById('vCodeImage');
image.src = "@Url.Action("GetVCode","Account")/?t=" + (new Date()).getTime();
}