MVC图片验证

1.创建一个验证类，里面有生成验证码的两个方法。

namespace YTJWGL_Common
{
    public class ValidatorCodeTools
    {
        #region 生成校验码图片
        public ValidatorCodeTools()
        {
        }
        /// <summary>
        /// 验证码的最大长度
        /// </summary>
        public int MaxLength
        {
            get { return ; }
        }
        /// <summary>
        /// 验证码的最小长度
        /// </summary>
        public int MinLength
        {
            get { return ; }
        }
        /// <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)
        {
            int[] randMembers = new int[length];
            int[] validateNums = new int[length];
            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(, Int32.MaxValue - length * );
            int[] seeks = new int[length];
            for (int i = ; i < length; i++)
            {
                beginSeek += ;
                seeks[i] = beginSeek;
            }
            //生成随机数字
            for (int i = ; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum =  * (int)Math.Pow(, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取随机数字
            for (int i = ; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(, numLength - );
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, ));
            }
            //生成验证码
            for (int i = ; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }
        /// <summary>
        /// 创建验证码的图片
        /// </summary>
        /// <param name="validateCode">验证码内容</param>
        /// <returns></returns>
        public byte[] CreateValidateGraphic(string validateCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), );
            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 = ; i < ; 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", , (FontStyle.Bold | FontStyle.Italic));
                LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(, , image.Width, image.Height),
                 Color.Blue, Color.DarkRed, 1.2f, true);
                g.DrawString(validateCode, font, brush, , );
                //画图片的前景干扰点
                for (int i = ; i < ; 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), , , image.Width - , image.Height - );
                //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();
            }
        }
        /// <summary>
        /// 得到验证码图片的长度
        /// </summary>
        /// <param name="validateNumLength">验证码的长度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
        {
            return (int)(validateNumLength * 12.0);
        }
        /// <summary>
        /// 得到验证码的高度
        /// </summary>
        /// <returns></returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }
        #endregion
    }
}

2.CreateValidateCode方法生成验证码内容，对应图片中的形如“54361”这样的数字。而CreateValidateGraphic该方法接收一个参数，把参数中的验证码转换为图片显示。在BLL层有两个方法：

namespace YTJWGL_Bll
{
    public class AdminService : BaseService<YTJWGL_Admin>, IAdminService
    {

        /// <summary>
        /// 生成验证码数字
        /// </summary>
        /// <param name="id">验证码位数，默认为5</param>
        /// <returns></returns>
        public string NewValidateCode(int id = )
        {
            ValidatorCodeTools obj = new ValidatorCodeTools();
            return obj.CreateValidateCode();
        }
        /// <summary>
        /// 验证码图片
        /// </summary>
        /// <param name="code"></param>
        /// <returns></returns>
        public byte[] NewValidateCodeGraphic(string code)
        {
            ValidatorCodeTools obj = new ValidatorCodeTools();
            return obj.CreateValidateGraphic(code);
        }
    }
}

3.新建一个Action:

namespace YTJWGL_WebUI.Areas.Admin.Controllers
{

    public class FrameController : Controller
    {
        //
        // GET: /Admin/Frame/
        #region Fields

        private readonly IAdminService _adminService;
        private readonly IAdminAuthorityService _adminAuthorityService;
        private readonly IAdminRoleService _adminRoleService;
        private readonly ILogService _logService;

        #endregion

        #region Constructors

        public FrameController(IAdminService adminService, IAdminAuthorityService adminAuthorityService, IAdminRoleService adminRoleService, ILogService logService)
        {
            this._adminService = adminService;
            this._adminAuthorityService = adminAuthorityService;
            this._adminRoleService = adminRoleService;
            this._logService = logService;
        }
        #endregion

        #region Admin

          public ActionResult GetValidatorGraphics()
            {
                string code = _adminService.NewValidateCode();
                Session["ValidatorCode"] = code;
                byte[] graphic =           _adminService.NewValidateCodeGraphic(code);
                return File(graphic, @"image/jpeg");
        }
        #endregion
    }
}

在Action中调用我们刚才在BLL层定义 的两个方法，返回这张验证码图片。因为http是无连接的，这个action仅仅响应用户一次访问请求，当用户点击登录后会将填写的验证码发送到服务器， 而这已经是第二次访问请求了，所以需要用Session用来保存刚才发往客户端的验证码。

　　那么，怎么在界面上请求这张验证码图片呢？

4.只需要使用<img>标签的src属性访问我们刚才的action。生成的效果如下：

<script type="text/javascript">
        //当点击图片时，刷新验证码
        $(function () {
            $("#valiCode").bind("click", function () {
                this.src = "@Url.Action("GetValidatorGraphics", "Frame")?time=" + (new Date()).getTime();
            });
        });
    </script>

5.给img标签添加click事件，点击过后重新访问生成验证码的action，由于验证中数字是随机生成的，新返回的验证码图片就不一样了。避免浏览器缓存影响，src链接附件了一个随机时间。