C#根据权重随机取记录

请求次数越多越精确，代码如下

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace testdemos
{
public partial class _default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string AdList = "A,B,C,D";
string AdWeight = "1,2,3,4";
for (int i = 0; i < 30; i++)
{
Response.Write(ShowStr(AdList, AdWeight));
Response.Write("<br>");
}
}
/// <summary>
/// 计算权重总合
/// </summary>
/// <param name="d">权重一维数组</param>
/// <returns></returns>
private int Sum(string[] d)
{
int Sum = 0;
for (int i = 0; i < d.Length; i++)
{
Sum += Convert.ToInt32(d[i]);
}
return Sum;
}

//随机数，
private 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);
}
/// <summary>
/// 随机数和权重计算当前数
/// </summary>
/// <param name="a">显示内容一维数组字符串</param>
/// <param name="b">权重一维数组字符串</param>
/// <returns></returns>
private string ShowStr(string a, string b)
{
string[] c = a.Split(',');
string[] d = b.Split(',');

//Random rd = new Random(DateTime.Now.Millisecond);
Random rd = new Random(GetRandomSeed());
int e = Sum(d);
int f = rd.Next(1, e);
int g = 0;
string h = "";
for (int i = 0; i < d.Length; i++)
{
g += Convert.ToInt32(d[i]);
if (g >= f)
{
h =c[i];
break;
}
}
return h;
}
}

}