1  public class VierificationCodeServices
 2  {  3 /// <summary>  4 /// 该方法用于生成指定位数的随机数  5 /// </summary>  6 /// <param name="VcodeNum">参数是随机数的位数</param>  7 /// <returns>返回一个随机数字符串</returns>  8 private string RndNum(int VcodeNum)  9  { 10 //验证码可以显示的字符集合 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[] { ',' });//拆分成数组 15 string code = "";//产生的随机数 16 int temp = -1;//记录上次随机数值，尽量避避免生产几个一样的随机数 17 18 Random rand = new Random(); 19 //采用一个简单的算法以保证生成随机数的不同 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));//初始化随机类 25  } 26 int t = rand.Next(61);//获取随机数 27 if (temp != -1 && temp == t) 28  { 29 return RndNum(VcodeNum);//如果获取的随机数重复，则递归调用 30  } 31 temp = t;//把本次产生的随机数记录起来 32 code += VcArray[t];//随机数的位数加一 33  } 34 return code; 35  } 36 37 /// <summary> 38 /// 该方法是将生成的随机数写入图像文件 39 /// </summary> 40 /// <param name="code">code是一个随机数</param> 41 /// <param name="numbers">生成位数（默认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 //验证码颜色集合 50 Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple }; 51 52 //验证码字体集合 53 string[] fonts = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" }; 54 55 56 //定义图像的大小，生成图像的实例 57 Img = new Bitmap((int)code.Length * 18, 32); 58 59 g = Graphics.FromImage(Img);//从Img对象生成新的Graphics对象 60 61 g.Clear(Color.White);//背景设为白色 62 63 //在随机位置画背景点 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 //验证码绘制在g中 71