验证码

（1）使用前需要New一下这个类
namespace PMPOrganization.Models
{
public class ValidateCode
{

//生成随机生成器
private Random random = new Random();

//验证码的最大长度
public int MaxLength
{
get { return 10; }
}

//验证码的最小长度
public int MinLength
{
get { return 1; }
}

#region 随机生成验证码(数字)
/// <summary>
/// 随机生成验证码(数字)
/// </summary>
/// <param name="length">指定验证码的长度</param>
/// <returns></returns>
public string CreateValidateCodeByShuZi(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;
}
#endregion

#region 随机生成验证码（大小写字母+数字）
/// <summary>
/// 随机生成验证码（大、小写字母+数字）
/// </summary>
/// <param name="yzmlength">验证码的长度</param>
/// <returns></returns>
public string CreateValidateCodeByShuZiAndZiMu(int yzmlength)
{
string yanzhengma = string.Empty;
var random = new Random((int)DateTime.Now.Ticks);
const string textArray = "ABCDEFGHG23KLMNPQRSTU45VWXYZ89abcdefghijk67mnpqrstuvwxyz";
for (var i = 0; i < yzmlength; i++)
{
yanzhengma = yanzhengma + textArray.Substring(random.Next() % textArray.Length, 1);
}
return yanzhengma;
}
#endregion

#region 随机生成验证码（大写字母+数字 或者是小写字母+数字）
/// <summary>
/// 随机生成验证码（大写字母+数字 或者是小写字母+数字）
/// </summary>
/// <param name="yzmlength">验证码长度</param>
/// <returns></returns>
private string CreateValidateCodeByShuZiAndZiMu2(int yzmlength)
{
int number;
char code;
string checkcode = string.Empty;
Random random = new Random();
for (int i = 0; i < 4; i++)
{
number = random.Next();
if (number % 2 == 0)
{
code = (char)('0' + (char)(number % 10));
}
else
{
code = (char)('A' + (char)(number % 26));
}
checkcode += code.ToString();
}
return checkcode;
}
#endregion

#region 随机生成颜色

private Color GetColor()
{
var corlors = new[] { Color.DarkSeaGreen, Color.Gray, Color.DarkSalmon, Color.Lavender };
return corlors[random.Next(corlors.Length)];
}
private Color GetColor2()
{
var corlors = new[] { Color.Blue, Color.Green, Color.HotPink, Color.MediumOrchid, Color.Olive, Color.Peru, };
return corlors[random.Next(corlors.Length)];
}

#endregion

#region 创建验证码的图片
/// <summary>
/// 创建验证码的图片
/// </summary>
/// <param name="validateCode">验证码</param>
/// <param name="width">width</param>
/// <param name="height">height</param>
public byte[] CreateValidateGraphic(string validateCode, int width, int height)
{
//Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 13.0),20);
Bitmap image = new Bitmap(width, height);
Graphics g = Graphics.FromImage(image);
try
{

//清空图片背景色
g.Clear(Color.White);
//画图片的干扰线
for (int i = 0; i < 15; 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(GetColor(), 1.7f), x1, y1, x2, y2);
}

var font = new Font("微软雅黑", 15, (FontStyle.Bold | FontStyle.Italic));
var brush = new LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height),
GetColor2(), GetColor2(), 1.5f, true);
g.DrawString(validateCode, font, brush, 5, 13);

//画图片的边框线
g.DrawRectangle(new Pen(Color.White), 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();
}
} 
#endregion

#region 得到验证码图片的长度
/// <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 * 16.0);
} 
#endregion

//得到验证码的高度
public static double GetImageHeight()
{
return 100;
}

}
}



//生成验证码
public void ShowValidateCodeImage()
{
try
{
Session["YanZhengMa"] = null;
var code = new ValidateCode();
var yanzhengma = code.CreateValidateCodeByShuZiAndZiMu(5);
var imagebytes = code.CreateValidateGraphic(yanzhengma, 90, 50);
Response.OutputStream.Write(imagebytes, 0, imagebytes.Length);
Session["YanZhengMa"] = yanzhengma;
}
catch (Exception ex)
{
Log.Error(ex, "PMPOrganization.Login::void ShowValidateCodeImage()");
}
}

 html页中<img src="/login/showValidateCodeImage" id=h/>

  jquery中$("#").attr("src", "/login/showValidateCodeImage?rom=" + Math.random());