一个图片验证码的HtmlHelper，原来的调用代码如下：
复制代码 代码如下:
<img id="validateCode" mailto:src='@Url.Action(%22GetValidateCode%22)'/>
<script language="javascript" type="text/javascript">
$(document).ready(function () {
$("#validateCode").bind("click", function () {
var url = $(this).attr("src");
url += "?" + Math.random();
$(this).attr("src", url);
});
});
</script>

封装成HtmlHelper后：
@Html.ValidateCode()
使用步骤如下：
1.建一个验证码Helper
复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;
using System.Linq.Expressions;
using System.Security.Policy;
using System.Text;
using System.Web;
using System.Web.Mvc;
using System.Web.Mvc.Resources;
using System.Web.Routing;
namespace MvcApplication1
{
public static class ValidateCodeHelper
{
private const string IdPrefix = "validateCode";
private const int Length = 4;
public static MvcHtmlString ValidateCode(this HtmlHelper helper)
{
return ValidateCode(helper, IdPrefix);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper,string id)
{
return ValidateCode(helper, id, Length);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper, string id, int length)
{
return ValidateCode(helper, id, length, null);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper, string id, object htmlAttributes)
{
return ValidateCode(helper, id, Length, htmlAttributes);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper, int length, object htmlAttributes)
{
return ValidateCode(helper, IdPrefix, length, htmlAttributes);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper, object htmlAttributes)
{
return ValidateCode(helper, 4, htmlAttributes);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper, int length)
{
return ValidateCode(helper,length, null);
}
public static MvcHtmlString ValidateCode(this HtmlHelper helper,string id,int length,object htmlAttributes)
{
string finalId = id + "_imgValidateCode";
var tagBuild = new TagBuilder("img");
tagBuild.GenerateId(finalId);
var defaultController = ((Route)RouteTable.Routes["Default"]).Defaults["controller"] + "/";
var controller = HttpContext.Current.Request.Url.Segments.Length == 1
? defaultController
: HttpContext.Current.Request.Url.Segments[1];
tagBuild.MergeAttribute("src", string.Format("/{0}GetValidateCode?length={1}",controller,length));
tagBuild.MergeAttribute("alt", "看不清？点我试试看！");
tagBuild.MergeAttribute("style","cursor:pointer;");
tagBuild.MergeAttributes(AnonymousObjectToHtmlAttributes(htmlAttributes));
var sb = new StringBuilder();
sb.Append("<script language=\"javascript\" type=\"text/javascript\">");
sb.Append("$(document).ready(function () {");
sb.AppendFormat("$(\"#{0}\").bind(\"click\", function () {{", finalId);
//sb.Append("$(this).attr(\"style\", \"cursor:pointer;\");");
sb.Append("var url = $(this).attr(\"src\");");
sb.Append("url += \"&\" + Math.random();");
sb.Append("$(this).attr(\"src\", url);");
sb.Append("});");
sb.Append("});");
sb.Append("</script>");
return MvcHtmlString.Create(tagBuild+sb.ToString());
}
public static RouteValueDictionary AnonymousObjectToHtmlAttributes(object htmlAttributes)
{
var result = new RouteValueDictionary();
if (htmlAttributes != null)
{
foreach (PropertyDescriptor property in TypeDescriptor.GetProperties(htmlAttributes))
{
result.Add(property.Name.Replace('_', '-'), property.GetValue(htmlAttributes));
}
}
return result;
}
}
}

2.生成验证码的代码：
复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.IO;
using System.Drawing.Imaging;
namespace MvcApplication1
{
public class ValidateCode
{
public ValidateCode()
{
}
/// <summary>
/// 验证码的最大长度
/// </summary>
public int MaxLength
{
get { return 10; }
}
/// <summary>
/// 验证码的最小长度
/// </summary>
public int MinLength
{
get { return 1; }
}
/// <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)
{
var randMembers = new int[length];
var validateNums = new int[length];
var validateNumberStr = "";
//生成起始序列值
var seekSeek = unchecked((int)DateTime.Now.Ticks);
var seekRand = new Random(seekSeek);
var beginSeek = (int)seekRand.Next(0, Int32.MaxValue - length * 10000);
var seeks = new int[length];
for (var i = 0; i < length; i++)
{
beginSeek += 10000;
seeks[i] = beginSeek;
}
//生成随机数字
for (var i = 0; i < length; i++)
{
var rand = new Random(seeks[i]);
var pownum = 1 * (int)Math.Pow(10, length);
randMembers[i] = rand.Next(pownum, Int32.MaxValue);
}
//抽取随机数字
for (var i = 0; i < length; i++)
{
var numStr = randMembers[i].ToString();
var numLength = numStr.Length;
var rand = new Random();
var numPosition = rand.Next(0, numLength - 1);
validateNums[i] = Int32.Parse(numStr.Substring(numPosition, 1));
}
//生成验证码
for (var i = 0; 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</param>
public byte[] CreateValidateGraphic(string validateCode)
{
var image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
var g = Graphics.FromImage(image);
try
{
//生成随机生成器
var 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++)
{
var x1 = random.Next(image.Width);
var x2 = random.Next(image.Width);
var y1 = random.Next(image.Height);
var 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));
string[] fontName = { "华文新魏", "宋体", "圆体", "黑体", "隶书" };
var font = new Font(fontName[new Random().Next(0, validateCode.Length)], 12, (FontStyle.Bold | FontStyle.Italic));
var 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);
//画图片的前景干扰点
for (var i = 0; i < 100; i++)
{
var x = random.Next(image.Width);
var 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
var 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 23;
}
}
}

3.建一个BaseController
复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
namespace MvcApplication1
{
public class BaseController:Controller
{
public ActionResult GetValidateCode(int length)
{
var vCode = new ValidateCode();
var code = vCode.CreateValidateCode(length);
Session["ValidateCode"] = code;
var bytes = vCode.CreateValidateGraphic(code);
return File(bytes, @"image/gif");
}
protected string GetValidateCode()
{
return Session["ValidateCode"].ToString();
}
}
}

4.让Controller继承BaseController：
复制代码 代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using System.Web.Security;
namespace MvcApplication1.Controllers
{
public class HomeController :BaseController
{
public ActionResult Index()
{
ViewBag.Message = "Welcome to ASP.NET MVC!";
return View();
}
public ActionResult About()
{
var code = GetValidateCode();
return View();
}
}
}

5.页面调用代码：
复制代码 代码如下:
@using MvcApplication1
@{
ViewBag.Title = "About Us";
}
<h2>About</h2>
<p>
Put content here.
</p>
@Html.ValidateCode()

6.验证码的效果图：

源码可以从这里下载： ValidateCode.rar