Silverlight 随机验证码生成图片

 1 var _IndextifyCode=IndentifyCode.Instance.CreateIndentifyCode(4);
 2 
 3 IndentifyCode.Instance.CreateImage(_IndextifyCode,"image名称",100,35);//100,35大小
 4 
 5  public class IndentifyCode
 6     {
 7         private static IndentifyCode instance = null;
 8         public static IndentifyCode Instance
 9         {
10             get
11             {
12                 return instance ?? (instance = new IndentifyCode());
13             }
14         }
15 
16  
17 
18         Random r = new Random(DateTime.Now.Millisecond);
19 
20         
21 
22  
23 
24 　　   #region 产生随机数
25         public string CreateIndentifyCode(int length)
26         {
27             //由于1,I,l,O,o,0容易混淆,则不显示
28             string allchar = "2,3,4,5,6,7,8,9,A,a,B,b,C,c,D,d,E,e,F,f," +
29                 "G,g,H,h,i,J,j,K,k,L,M,m,N,n,P,p,Q,q,R,r,S,s," +
30                 "T,t,U,u,V,v,W,w,X,x,Y,y,Z,z";
31             string[] allchararray = allchar.Split(',');
32             string randomcode = "";
33             int temp = -1;
34             Random rand = new Random();
35             for (int i = 0; i < length; i++)
36             {
37                 if (temp != -1)
38                 {
39                     rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
40                 }
41                 int t = rand.Next(allchararray.Length);
42                 if (temp == t)
43                 {
44                     return CreateIndentifyCode(length);
45                 }
46                 temp = t;
47                 randomcode += allchararray[t];
48             }
49             return randomcode;
50         }
51         #endregion
52 
53     }