ASP.NET MVC實現網站驗證碼功能

網站添加驗證碼，主要為防止機器人程序批量注冊，或對特定的注冊用戶用特定程序暴力破解方式，以進行不斷的登錄、灌水等危害網站的操作。驗證碼被廣泛應用在注冊、登錄、留言等提交信息到服務器端處理的頁面中。

     在ASP.NET網站中應用驗證碼是很容易的，網上有很多的解決方案。最近在做一個OA項目，因系統采用的ASP.NET MVC框架，同樣在登錄頁中需用到驗證碼，故需將原來在ASP.NET網站中使用的驗證碼移植到ASP.NET MVC中。

　　  原ASP.NET網站用來生成驗證碼的類文件ValidateCode.cs：

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Web.UI;
using System.Drawing.Drawing2D;
using System.IO;

namespace SeniOA.MVC
{
    /// <summary>
    /// 生成驗證碼的類
    /// </summary>
    public class ValidateCode
    {
        public ValidateCode()
        {
        }
        /// <summary>
        /// 驗證碼的最大長度
        /// </summary>
        public int MaxLength
        {
            get { return 10; }
        }
        /// <summary>
        /// 驗證碼的最小長度
        /// </summary>
        public int MinLength
        {
            get { return 1; }
        }
        /// <summary>
        /// 生成驗證碼
        /// </summary>
        /// <param name="length">指定驗證碼的長度</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(0, Int32.MaxValue - length * 10000);
            int[] seeks = new int[length];
            for (int i = 0; i < length; i++)
            {
                beginSeek += 10000;
                seeks[i] = beginSeek;
            }
            //生成隨機數字
            for (int i = 0; i < length; i++)
            {
                Random rand = new Random(seeks[i]);
                int pownum = 1 * (int)Math.Pow(10, length);
                randMembers[i] = rand.Next(pownum, Int32.MaxValue);
            }
            //抽取隨機數字
            for (int i = 0; i < length; i++)
            {
                string numStr = randMembers[i].ToString();
                int numLength = numStr.Length;
                Random rand = new Random();
                int numPosition = rand.Next(0, numLength - 1);
                validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
            }
            //生成驗證碼
            for (int i = 0; i < length; i++)
            {
                validateNumberStr += validateNums[i].ToString();
            }
            return validateNumberStr;
        }
        /// <summary>
        /// 創建驗證碼的圖片
        /// </summary>
        /// <param name="containsPage">要輸出到的page對象</param>
        /// <param name="validateNum">驗證碼</param>
        public void CreateValidateGraphic(string validateCode)
        {
            Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
            Graphics g = Graphics.FromImage(image);
            try
            {
                //生成隨機生成器
                Random random = new Random();
                //清空圖片背景色
                g.Clear(Color.White);
                //畫圖片的干擾線
                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);
                //畫圖片的前景干擾點
                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()));
                }
                //畫圖片的邊框線
                g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
                //保存圖片數據
                MemoryStream stream = new MemoryStream();
                image.Save(stream, ImageFormat.Jpeg);
                //輸出圖片流
                containsPage.Response.Clear();
                containsPage.Response.ContentType = "image/jpeg";
                containsPage.Response.BinaryWrite(stream.ToArray());
            }
            finally
            {
                g.Dispose();
                image.Dispose();
            }
        }
        /// <summary>
        /// 得到驗證碼圖片的長度
        /// </summary>
        /// <param name="validateNumLength">驗證碼的長度</param>
        /// <returns></returns>
        public static int GetImageWidth(int validateNumLength)
        {
            return (int)(validateNumLength * 12.0);
        }
        /// <summary>
        /// 得到驗證碼的高度
        /// </summary>
        /// <returns></returns>
        public static double GetImageHeight()
        {
            return 22.5;
        }
    }
}

　　為適合ASP.NET MVC框架，修改其輸出圖片流的方法CreateValidateGraphic為：

/// <summary>
/// 創建驗證碼的圖片
/// </summary>
/// <param name="containsPage">要輸出到的page對象</param>
/// <param name="validateNum">驗證碼</param>
public byte[] CreateValidateGraphic(string validateCode)
{
    Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
    Graphics g = Graphics.FromImage(image);
    try
    {
        //生成隨機生成器
        Random random = new Random();
        //清空圖片背景色
        g.Clear(Color.White);
        //畫圖片的干擾線
        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);
        //畫圖片的前景干擾點
        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()));
        }
        //畫圖片的邊框線
        g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
        //保存圖片數據
        MemoryStream stream = new MemoryStream();
        image.Save(stream, ImageFormat.Jpeg);
        //輸出圖片流
        return stream.ToArray();
    }
    finally
    {
        g.Dispose();
        image.Dispose();
    }
}

　　在Controller.cs中，添加Action，用來設置將生成的驗證碼存入Session，並輸出驗證碼圖片：

public ActionResult GetValidateCode()
{
    ValidateCode vCode = new ValidateCode();
    string code = vCode.CreateValidateCode(5);
    Session["ValidateCode"] = code;
    byte[] bytes = vCode.CreateValidateGraphic(code);
    return File(bytes, @"image/jpeg");
}

調用方式為：在需要使用驗證碼的頁面中，加入<img>標簽：
<img id="valiCode" style="cursor: pointer;" src="../Account/GetValidateCode" alt="驗證碼" />

 到於Account/Login這個Action中的處理，只需加入對Session中驗證碼的判斷：

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Login(string userName, string password, bool rememberMe, string returnUrl,string code)
{
    if (Session["ValidateCode"].ToString() != code)
    {
        ModelState.AddModelError("code", "validate code is error");
        return View();
    }

    //此處驗證用戶名、密碼
    if (!ValidateLogOn(userName, password))
    {
        return View();
    }

    //驗證成功
    FormsAuthentication.SetAuthCookie(userName, rememberMe);

    if (!String.IsNullOrEmpty(returnUrl))
    {
        return Redirect(returnUrl);
    }
    else
    {
        return RedirectToAction("Index", "Home");
    }
}

 為實現登錄頁中，點擊圖片切換驗證碼，可以登錄頁中加入此JS代碼實現刷新驗證碼：

<script type="text/javascript" src="http://www.cnblogs.com/Scripts/jquery-1.3.2-vsdoc.js"></script>
<script type="text/javascript">
    $(function() {
    $("#valiCode").bind("click", function() {
        this.src = "../Account/GetValidateCode?time=" + (new Date()).getTime();
        });
        //alert("good");
    });
</script>