mvc3 验证码，用Html扩展来实现

1.类代码如下

public static class ValidateCode
{

/// <summary>
/// 验证码的最大长度
/// </summary>
public static int MaxLength
{
get { return 10; }
}
/// <summary>
/// 验证码的最小长度
/// </summary>
public static int MinLength
{
get { return 1; }
}

/// <summary>
/// 生成验证码
/// </summary>
/// <returns></returns>
public static MvcHtmlString GetValidateCode(this HtmlHelper helper)
{
return MvcHtmlString.Create("/Home/ValidateCode");
}
/// <summary>
/// 生成验证码
/// </summary>
/// <param name="length">指定验证码的长度</param>
/// <returns></returns>
public static 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;
}
//生成随机数字
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);
}
//抽取随机数字
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));
}
//生成验证码
for (int 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 static byte[] CreateValidateGraphic(string validateCode)
{
Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 12.0), 22);
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 = 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);
//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();
}
}

/// <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;
}
}

2.定义个Action

/// <summary>
/// 验证码的action
/// </summary>
/// <returns></returns>
public ActionResult ValidateCode()
{
return File(Framework.UI.ValidateCode.CreateValidateGraphic(Framework.UI.ValidateCode.CreateValidateCode(4)), @"image/jpeg");
}

3.Razor调用

<img src="@Html.GetValidateCode()" alt="" id="vadimg" title="看不清楚请刷新!" onclick="this.src='@Html.GetValidateCode()?';+(new Date().getTime());" style="cursor:pointer" align="absmiddle">

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