C#随机数产生器

 1 //产生订单号的随机数
 2     public class OrderNumGen
 3     {
 4         public string getNewOrderNum()
 5         {
 6             StringBuilder builder = new StringBuilder();
 7             builder.Append(RandomString(4, false));
 8             builder.Append("-");
 9             builder.Append(RandomNumber(100, 999));
10             builder.Append("-");
11             builder.Append(RandomString(2, false));
12             return builder.ToString();            
13         }
14         //size=长度，lowerCase=true 随机字母小写/false=大写
15         private string RandomString(int size, bool lowerCase)
16         {
17             StringBuilder builder = new StringBuilder();
18             Random random = new Random();
19             char ch;
20             for (int i = 0; i < size; i++)
21             {
22                 ch = Convert.ToChar(Convert.ToInt32(Math.Floor(26 * random.NextDouble() + 65)));
23                 builder.Append(ch);
24             }
25             if (lowerCase)
26                 return builder.ToString().ToLower();
27             return builder.ToString();
28         }
29         //产生从min到max的随机数
30         private int RandomNumber(int min, int max)
31         {
32             Random random = new Random();
33             return random.Next(min, max);
34         }