要一个随机验证码的html代码

public static string RandomNum(int n)

{

string strchar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z"

string[] VcArray = strchar.Split(',')

string VNum = ""

int temp = -1

Random rand = new Random()

for (int i = 1i <n + 1i++)

{

if (temp != -1)

{

rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks))

}

int t = rand.Next(61)

if (temp != -1 &&temp == t)

{

return RandomNum(n)

}

temp = t

VNum += VcArray[t]

}

return VNum

}

#endregion

#region 验证码图片

public static void CheckCodes(string M_CheckCode)

{

Random rand = new Random()

int iwidth = (int)(M_CheckCode.Length * 15)

System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 22)

Graphics g = Graphics.FromImage(image)

g.Clear(Color.White)

//画图片的背景噪音线20条

for (int i = 0i <20i++)

{

int x1 = rand.Next(image.Width)

int x2 = rand.Next(image.Width)

int y1 = rand.Next(image.Height)

int y2 = rand.Next(image.Height)

g.DrawLine(new Pen(Color.Silver), x1, x2, y1, y2)

}

//定义颜色

Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple, Color.YellowGreen }

//定义字体

string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体", "新宋体" }

//随机输出噪点

for (int i = 0i <50i++)

{

int x = rand.Next(image.Width)

int y = rand.Next(image.Height)

g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1)

}

//输出不同字体和颜色的验证码字符

for (int i = 0i <M_CheckCode.Lengthi++)

{

int cindex = rand.Next(7)

int findex = rand.Next(6)

Font f = new System.Drawing.Font(font[findex], 12, System.Drawing.FontStyle.Bold)

Brush b = new System.Drawing.SolidBrush(c[cindex])

int ii = 4

if ((i + 1) % 2 == 0)

{

ii = 2

}

g.DrawString(M_CheckCode.Substring(i, 1), f, b, 3 + (i * 12), ii)

}

//画一个边框

g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1)

//输出到浏览器

System.IO.MemoryStream ms = new System.IO.MemoryStream()

image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif)

HttpContext.Current.Response.ClearContent()

//Response.ClearContent()

HttpContext.Current.Response.ContentType = "image/gif"

HttpContext.Current.Response.BinaryWrite(ms.ToArray())

g.Dispose()

image.Dispose()

}

#endregion

1、验证码一般是由后台生成的图片，如果用HTML制作的话很容易被软件获取，如果要用HTML的话就用javascript生成随机数。

2、在写一个英文字母的数组，用随机数来取下标吧，如果只用数字验证码的话随机数就可以，不过验证码不建议用javascript制作。