C# 生成随机数类

using System;
using System.Collections.Generic;
using System.Text;
using System.Collections.Generic;

/// <summary>
/// 功能描述：类GetRandomPassword为了得到随机密码 
/// </summary>
public class GetRandom
{
    public GetRandom() { }

    /// <summary>
    /// 返回指定位数的随机数
    /// </summary>
    /// <param name="median">随机数位数(非负数)</param>
    /// <returns>string</returns>
    public  string GetStrRandom(int median)
    {
        Random ra = new Random();
        string str = "";
        string newstr = "";
        int l1 = median / 3;
        int l2 = median / 3;
        int l3 = median / 3 + median % 3;

        int[] lower = new int[l1];//小写字母
        int[] upper = new int[l2];//大写字母
        int[] num = new int[l3]; //数字

        byte[] bs1 = new byte[l1]; //存放小写字母
        byte[] bs2 = new byte[l2]; //存放大写字母

        Encoding en = Encoding.Default;

        #region //初始化随机数和字母
        for (int i = 0; i < lower.Length; i++)
        {
            lower[i] = ra.Next(65, 91);
            bs1[i] = byte.Parse(lower[i].ToString());
        }
        for (int j = 0; j < upper.Length; j++)
        {
            upper[j] = ra.Next(97, 123);
            bs2[j] = byte.Parse(upper[j].ToString());
        }
        for (int k = 0; k < num.Length; k++)
        {
            num[k] = ra.Next(0, 10);
        }
        #endregion

        string tempnum = "";
        for (int u = 0; u < num.Length; u++)
        {
            tempnum += num[u];
        }
        //拼接成临时字符串，方便按照下标取值
        str += en.GetString(bs1) + en.GetString(bs2) + tempnum;

        List<string> li = new List<string>();
        for (int a = 0; a < str.Length; a++)
        {
            li.Insert(a, str[a].ToString());
        }

        int count = 0;
        while (li.Count != 0)
        {
            count = ra.Next(0, li.Count);
            newstr += li[count];
            li.RemoveAt(count);
        }

        return newstr;
    }


    public string GetNumRandom(int median)
    {
        Random ra = new Random();

        string tempnum = "";


        int[] num = new int[median]; //数字


        #region //初始化随机数

        for (int k = 0; k < num.Length; k++)
        {
            num[k] = ra.Next(0, 10);
        }
        #endregion

   
        for (int u = 0; u < num.Length; u++)
        {
            tempnum += num[u];
        }



        return tempnum;
    }


}