Silverlight 随机验证码生成图片

var _IndextifyCode=IndentifyCode.Instance.CreateIndentifyCode(4);

IndentifyCode.Instance.CreateImage(_IndextifyCode,"image名称",100,35);//100,35大小

 public class IndentifyCode
    {
        private static IndentifyCode instance = null;
        public static IndentifyCode Instance
        {
            get
            {
                return instance ?? (instance = new IndentifyCode());
            }
        }

 

        Random r = new Random(DateTime.Now.Millisecond);

        

 

　　   #region 产生随机数
        public string CreateIndentifyCode(int length)
        {
            //由于1,I,l,O,o,0容易混淆,则不显示
            string allchar = "2,3,4,5,6,7,8,9,A,a,B,b,C,c,D,d,E,e,F,f," +
                "G,g,H,h,i,J,j,K,k,L,M,m,N,n,P,p,Q,q,R,r,S,s," +
                "T,t,U,u,V,v,W,w,X,x,Y,y,Z,z";
            string[] allchararray = allchar.Split(',');
            string randomcode = "";
            int temp = -1;
            Random rand = new Random();
            for (int i = 0; i < length; i++)
            {
                if (temp != -1)
                {
                    rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
                }
                int t = rand.Next(allchararray.Length);
                if (temp == t)
                {
                    return CreateIndentifyCode(length);
                }
                temp = t;
                randomcode += allchararray[t];
            }
            return randomcode;
        }
        #endregion

    }