.NET产生随机数

using System;
using System.Configuration;
using System.Text;
using System.Data;

namespace ZC.Utils
{
    /// <summary>
    /// Assistant 的摘要说明。
    /// </summary>
    public sealed class RandomHelper
    {        
            
        #region

/// <summary>
        /// 从字符串里随机得到，规定个数的字符串.
        /// </summary>
        /// <param name="allChar"></param>
        /// <param name="CodeCount"></param>
        /// <returns></returns>
        public static string GetRandomCode(string allChar, int CodeCount)
        {
            //string allChar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
            string[] allCharArray = allChar.Split(‘,‘);
            string RandomCode = "";
            int temp = -1;
            Random rand = new Random();
            for (int i=0;i<CodeCount;i++)
            {
                if (temp != -1)
                {
                    rand = new Random(temp*i*((int) DateTime.Now.Ticks));
                }

int t = rand.Next(allCharArray.Length-1);

while (temp == t)
                {
                    t = rand.Next(allCharArray.Length-1);
                }
        
                temp = t;
                RandomCode += allCharArray[t];
            }
            return RandomCode;
        }

/// <summary>
        /// 从字符串里随机得到，规定个数的字符串.
        /// </summary>
        /// <param name="allChar"></param>
        /// <param name="CodeCount"></param>
        /// <returns></returns>
        public static  string GetRandomCode(int CodeCount)
        {
            string allChar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
            string[] allCharArray = allChar.Split(‘,‘);
            string RandomCode = "";
            int temp = -1;
            Random rand = new Random(GetRandomSeed());
            for (int i = 0; i < CodeCount; i++)
            {
                if (temp != -1)
                {
                    //rand = new Random(temp * i * ((int)DateTime.Now.Ticks));
                    rand = new Random(GetRandomSeed());
                }

int t = rand.Next(allCharArray.Length - 1);

while (temp == t)
                {
                    t = rand.Next(allCharArray.Length - 1);
                }

temp = t;
                RandomCode += allCharArray[t];
            }
            return RandomCode;
        }

static int GetRandomSeed()
        {
            byte[] bytes = new byte[4];
            System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
            rng.GetBytes(bytes);
            return BitConverter.ToInt32(bytes, 0);
        }

#endregion

}
}