验证码，字体旋转。

Code.cs

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.Text;

namespace NationalUnion.Member.Models

{

    /// <summary>

    /// 生成验证码的类

    /// </summary>

    public class ValidateCode

    {
/// <summary>

        /// 生成验证码

        /// </summary>

        /// <param name="length">指定验证码的长度</param>

        /// <returns></returns>

        public string CreateValidateCode(int length)

        {

            StringBuilder strCodeBuilder = new StringBuilder();

            string strCode = "0123456789abcdefghijkmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";
List<char> vCharList = strCode.ToList<char>();

            int maxValule = vCharList.Count() - 1;

            for (int i = 0; i < length; i++)

            {

                Random rd = new Random();

                int number=rd.Next(0, maxValule);

                string strValue = vCharList[number].ToString();

                strCodeBuilder.Append(strValue);

            }

            return strCodeBuilder.ToString();

        }
public byte[] CreateValidateGraphicMatrix(string validateCode)

        {

            Bitmap image = new Bitmap(80, 30);

            Graphics g = Graphics.FromImage(image);

            try

            {

                Matrix matrix = new Matrix();//Matrix封装表示几何变换的 3 x 3 仿射矩阵
//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", 14, (FontStyle.Bold | FontStyle.Italic));

                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),

                 Color.Blue, Color.DarkRed, 1.2f, true);
char[] strValue = validateCode.ToCharArray();
for (int i = 0; i < strValue.Length; i++)

                {

                    int y = 2;

                    if (i % 2 == 0)

                    {

                        y = -15 - i * 5;

                        matrix.Rotate(30);//对此 Matrix 沿原点顺时针旋转指定角度

                    }

                    else

                    {

                        matrix.Rotate(-30);//对此 Matrix 沿原点顺时针旋转指定角度

                    }

                    g.Transform = matrix;

                    g.DrawString(strValue[i].ToString(), font, brush, 20 + i * 15, y);

                }
//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

                return stream.ToArray();

            }

            finally

            {

                g.Dispose();

                image.Dispose();

            }

        }

    }

}

Controller

using NationalUnion.Member.Models;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.Mvc;

namespace NationalUnion.Member.Controllers

{

    public class HomeController : Controller

    {
public ActionResult Index()

        {

            return View();

        }
public ActionResult ValidateCode()

        {

            ValidateCode vCode = new ValidateCode();

            string code = vCode.CreateValidateCode(4);

            Session["ValidateCode"] = code;

            byte[] bytes = vCode.CreateValidateGraphicMatrix(code);

            return File(bytes, @"image/jpeg");
}

    }

}

Index.cshml

@{

    ViewBag.Title = "Index";

}

<h2>Index</h2>

    <div>

        <a href="@Url.Action("UserBasesicInfo","UserCenter")">进入用户中心</a>

        <img id="valiCode" style="cursor: pointer;" src="@Url.Action("ValidateCode","Home")" alt="验证码" />

    </div>

生成的效果: