Asp.net mvc生成验证码

1.生成验证码类

 using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 using System.Web.Mvc;
 using System.IO;
 using System.Drawing;
 using System.Web;
 
 namespace SimpleNews.FrontEnd
 {
     public class ToolController : MyControllerBase
     {
         /// <summary>
         /// 生成验证码字符串
         /// </summary>
         /// <param name="codeLen">验证码字符长度</param>
         /// <returns>返回验证码字符串</returns>
         private static string MakeCode(int codeLen)
         {
             if (codeLen < )
             {
                 return string.Empty;
             }
             int number;
             StringBuilder sbCheckCode = new StringBuilder();
             Random random = new Random();
 
             for (int index = ; index < codeLen; index++)
             {
                 number = random.Next();
 
                 if (number %  == )
                 {
                     sbCheckCode.Append((char)('' + (char)(number % ))); //生成数字
                 }
                 else
                 {
                     sbCheckCode.Append((char)('A' + (char)(number % ))); //生成字母
                 }
             }
             return sbCheckCode.ToString();
         }
 
         ///<summary>
         /// 获取验证码图片流
         /// </summary>
         /// <param name="checkCode">验证码字符串</param>
         /// <returns>返回验证码图片流</returns>
         public static MemoryStream CreateCodeImg(string checkCode)
         {
             if (string.IsNullOrEmpty(checkCode))
             {
                 return null;
             }
             Bitmap image = new Bitmap((int)Math.Ceiling((checkCode.Length * 12.5)), );
             Graphics graphic = Graphics.FromImage(image);
             try
             {
                 Random random = new Random();
                 graphic.Clear(Color.White);
                 int x1 = , y1 = , x2 = , y2 = ;
                 for (int index = ; index < ; index++)
                 {
                     x1 = random.Next(image.Width);
                     x2 = random.Next(image.Width);
                     y1 = random.Next(image.Height);
                     y2 = random.Next(image.Height);
 
                     graphic.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
                 }
                 Font font = new Font("Arial", , (FontStyle.Bold | FontStyle.Italic));
                 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(, , image.Width, image.Height), Color.Red, Color.DarkRed, 1.2f, true);
                 graphic.DrawString(checkCode, font, brush, , );
 
                 int x = ;
                 int y = ;
 
                 //画图片的前景噪音点
                 for (int i = ; i < ; i++)
                 {
                     x = random.Next(image.Width);
                     y = random.Next(image.Height);
 
                     image.SetPixel(x, y, Color.FromArgb(random.Next()));
                 }
                 //画图片的边框线
                 graphic.DrawRectangle(new Pen(Color.Silver), , , image.Width - , image.Height - );
                 //将图片验证码保存为流Stream返回
                 System.IO.MemoryStream ms = new System.IO.MemoryStream();
                 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
                 return ms;
             }
             finally
             {
                 graphic.Dispose();
                 image.Dispose();
             }
         }
 
         /// <summary>
         /// 获取验证码
         /// </summary>
         /// <returns></returns>
         public ActionResult GetValidateCode()
         {
             string code = MakeCode();
             Session["ValidateCode"] = code;
             MemoryStream ms = CreateCodeImg(code);
             return File(ms.ToArray(), @"image/jpeg");
         }
 
     }
 }

2.前端Html页面

 <span>验证码:<input name="ValidateCode" type="text" value="" class="input2" id="txtValidateCode" size="" maxlength=""   >
                             <img src="../Tool/GetValidateCode" style="cursor: pointer;" name="checkcode" border=""
                                 id="valiCode" alt="验证码" class="Ysm" />
                             </span>

  $(function () {
             $("#valiCode").bind("click", function () {
                 this.src = "../Tool/GetValidateCode?time=" + (new Date()).getTime();
             });
         });

3.后台验证输入的验证码

 string validateCode = (string)Request.Form["ValidateCode"]??"";
             if (string.IsNullOrEmpty(validateCode))
             {
                 ModelState.AddModelError("validateCodeError","验证码错误！");
                 return View();
             }
             if (Session["ValidateCode"]!=null&&Session["ValidateCode"].ToString().ToLower() != validateCode.ToLower())
             {
                 ModelState.AddModelError("validateCodeError", "验证码错误！");
                 return View();
             }