随机生成登录验证码（4位）

public ActionResult Index()
{
return View();

}
///

/// 生成验证码
///

///
public ActionResult YZM()
{
string oldcode = TempData["SecurityCode"] as string;
string code = CreateRandomCode(4); //验证码的字符为4个
Session["YZMCode"] = code;
TempData["SecurityCode"] = code; //验证码存放在TempData中
return File(CreateValidateGraphic(code), "image/Jpeg");
}
///

/// 验证码校验
///

///
///
public JsonResult YZMCheck(string code)
{
string msg = null;//返回的信息
bool succ = false;//是否成功
string yzmcode = Session["YZMCode"].ToString();
if(code==yzmcode)
{
succ = true;
msg = "验证成功！";
}
else
{
succ = false;
msg = "验证失败！";
}
var json = new { msg = msg, succ = succ };
return Json(json);
}
///

/// 生成随机的字符串
///

///
///
public string CreateRandomCode(int codeCount)
{
string allChar = "0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,a,b,c,d,e,f,g,h,i,g,k,l,m,n,o,p,q,r,F,G,H,I,G,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z,s,t,u,v,w,x,y,z";
string[] allCharArray = allChar.Split(‘,‘);
string randomCode = "";
int temp = -1;
Random rand = new Random();
for (int i = 0; i )
{
if (temp != -1)
{
rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
}
int t = rand.Next(35);
if (temp == t)
{
return CreateRandomCode(codeCount);
}
temp = t;
randomCode += allCharArray[t];
}
return randomCode;
}
///

/// 创建验证码图片
///

///
///
public byte[] CreateValidateGraphic(string validateCode)
{
Bitmap image = new Bitmap((int)Math.Ceiling(validateCode.Length * 16.0), 27);
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, x2, y1, y2);
}
Font font = new Font("Arial", 13, (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);
//画图片的前景干扰线
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();
}
}