1  public class VierificationCodeServices
 2     {
 3         /// <summary>  
 4         /// 該方法用於生成指定位數的隨機數  
 5         /// </summary>  
 6         /// <param name="VcodeNum">引數是隨機數的位數</param>  
 7         /// <returns>返回一個隨機數字符串</returns>  
 8         private string RndNum(int VcodeNum)
 
 9         {
10             //驗證碼可以顯示的字元集合  
11             string Vchar = "0,1,2,3,4,5,6,7,8,9,a,b,c,d,e,f,g,h,i,j,k,l,m,n,p" +
12                 ",q,r,s,t,u,v,w,x,y,z,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,P,Q" +
13                 ",R,S,T,U,V,W,X,Y,Z";
14             string[] VcArray = Vchar.Split(new Char[] { '
 
,' });//拆分成陣列   
15             string code = "";//產生的隨機數  
16             int temp = -1;//記錄上次隨機數值，儘量避避免生產幾個一樣的隨機數  
17 
18             Random rand = new Random();
19             //採用一個簡單的演算法以保證生成隨機數的不同  
20             for (int i = 1; i < VcodeNum + 1; i++)
21             {
22                 if (temp != -1
 
)
23                 {
24                     rand = new Random(i * temp * unchecked((int)DateTime.Now.Ticks));//初始化隨機類  
25                 }
26                 int t = rand.Next(61);//獲取隨機數  
27                 if (temp != -1 && temp == t)
28                 {
29                     return RndNum(VcodeNum);//如果獲取的隨機數重複，則遞迴呼叫  
30                 }
31                 temp = t;//把本次產生的隨機數記錄起來  
32                 code += VcArray[t];//隨機數的位數加一  
33             }
34             return code;
35         }
36 
37         /// <summary>  
38         /// 該方法是將生成的隨機數寫入影象檔案  
39         /// </summary>  
40         /// <param name="code">code是一個隨機數</param>
41         /// <param name="numbers">生成位數（預設4位）</param>  
42         public MemoryStream Create(out string code, int numbers = 4)
43         {
44             code = RndNum(numbers);
45             Bitmap Img = null;
46             Graphics g = null;
47             MemoryStream ms = null;
48             Random random = new Random();
49             //驗證碼顏色集合  
50             Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };
51 
52             //驗證碼字型集合
53             string[] fonts = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋體" };
54 
55 
56             //定義影象的大小，生成影象的例項  
57             Img = new Bitmap((int)code.Length * 18, 32);
58 
59             g = Graphics.FromImage(Img);//從Img物件生成新的Graphics物件    
60 
61             g.Clear(Color.White);//背景設為白色  
62 
63             //在隨機位置畫背景點  
64             for (int i = 0; i < 100; i++)
65             {
66                 int x = random.Next(Img.Width);
67                 int y = random.Next(Img.Height);
68                 g.DrawRectangle(new Pen(Color.LightGray, 0), x, y, 1, 1);
69             }
70             //驗證碼繪製在g中  
71             for (int i = 0; i < code.Length; i++)
72             {
73                 int cindex = random.Next(7);//隨機顏色索引值  
74                 int findex = random.Next(5);//隨機字型索引值  
75                 Font f = new Font(fonts[findex], 15, FontStyle.Bold);//字型  
76                 Brush b = new SolidBrush(c[cindex]);//顏色  
77                 int ii = 4;
78                 if ((i + 1) % 2 == 0)//控制驗證碼不在同一高度  
79                 {
80                     ii = 2;
81                 }
82                 g.DrawString(code.Substring(i, 1), f, b, 3 + (i * 12), ii);//繪製一個驗證字元  
83             }
84             ms = new MemoryStream();//生成記憶體流物件  
85             Img.Save(ms, ImageFormat.Jpeg);//將此影象以Png影象檔案的格式儲存到流中  
86 
87             //回收資源  
88             g.Dispose();
89             Img.Dispose();
90             return ms;
91         }
92     }