GUID转换成16位字符串或19位数据（确保唯一）

    /// <summary>
    /// 根据GUID获取16位的唯一字符串
    /// </summary>
    /// <param name=\"guid\"></param>
    /// <returns></returns>
    public static string GuidTo16String()
    {
        long i = 1;
        foreach (byte b in Guid.NewGuid().ToByteArray())
            i *= ((int)b + 1);
        return string.Format("{0:x}", i - DateTime.Now.Ticks);
    }
    /// <summary>
    /// 根据GUID获取19位的唯一数字序列
    /// </summary>
    /// <returns></returns>
    public static long GuidToLongID()
    {
        byte[] buffer = Guid.NewGuid().ToByteArray();
        return BitConverter.ToInt64(buffer, 0);
    } 

    /// <summary>
    /// 生成22位唯一的数字 并发可用
    /// </summary>
    /// <returns></returns>
    public static string GenerateUniqueID()
    {
        System.Threading.Thread.Sleep(1); //保证yyyyMMddHHmmssffff唯一
        Random d = new Random(BitConverter.ToInt32(Guid.NewGuid().ToByteArray(), 0));
        string strUnique = DateTime.Now.ToString("yyyyMMddHHmmssffff") + d.Next(1000, 9999);
        return strUnique;
    }