C#中文随机数实现方法

/// <summary>
/// 随机中文码
/// </summary>
/// <returns></returns>
private string GetRndCh()
{
 System.Text.Encoding gb = System.Text.Encoding.Default;
 //获取GB2312编码页（表）
 object[] bytes = CreateRegionCode(4);
 //调用函数产生4个随机中文汉字编码
 string[] str = new string[4];
 System.Text.StringBuilder sb = new System.Text.StringBuilder();
 for (int i = 0; i < 4; i++)
 {
   //根据汉字编码的字节数组解码出中文汉字
   str[i] = gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));
   sb.Append( str[i].ToString());
 }
 return sb.ToString ();
 }
 /// <summary>
 /// 产生随机中文汉字编码
 /// </summary>
 /// <param name="strlength"></param>
 /// <returns></returns>
 private static object[] CreateRegionCode(int strlength)
 {
 //定义一个字符串数组储存汉字编码的组成元素
 string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; 
 Random rnd = new Random();
 object[] bytes = new object[strlength];
 for (int i = 0; i < strlength; i++)
 {
   //区位码第1位
   int r1 = rnd.Next(11, 14);
   string str_r1 = rBase[r1].Trim();
   //区位码第2位
   rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);
   int r2;
   if (r1 == 13)
   {
   r2 = rnd.Next(0, 7);
   }
   else
   {
   r2 = rnd.Next(0, 16);
   }
   string str_r2 = rBase[r2].Trim();
   //区位码第3位
   rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);
   //更换随机种子
   int r3 = rnd.Next(10, 16);
   string str_r3 = rBase[r3].Trim();
   //区位码第4位
   rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
   int r4;
   if (r3 == 10)
   {
   r4 = rnd.Next(1, 16);
   }
   else if (r3 == 15)
   {
   r4 = rnd.Next(0, 15);
   }
   else
   {
   r4 = rnd.Next(0, 16);
   }
   string str_r4 = rBase[r4].Trim();
   //定义两个字节变量存储产生的随机汉字区位码
   byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
   byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);
   //将两个字节变量存储在字节数组中
   byte[] str_r = new byte[] { byte1, byte2 };
   //将产生的一个汉字的字节数组放入object数组中
   bytes.SetValue(str_r, i);
 }
 return bytes;
}