/*
 * 名稱:RandomId
 * 功能:生成隨機ID
 * 作者:冰麟輕武
 * 日期:2012年1月31日 03:36:28
 * 版本:1.0
 * 最后更新:2012年1月31日 03:36:28
 */

using System;
using System.Text;

namespace blqw
{
    public sealed class RandomId : IFormattable
    {

        /// <summary> 1234567890qwertyuiopasdfghjklzxcvbnm1234567890QWERTYUIOPASDFGHJKLZXCVBNM
        /// </summary>
        public const string ALLWORDS = "1234567890qwertyuiopasdfghjklzxcvbnm1234567890QWERTYUIOPASDFGHJKLZXCVBNM";
        /// <summary> 2345678wertyuiopasdfghjkzxcvbnm23456780QWERTYUPASDFGHJKLZXCVBNM
        /// </summary>
        public const string SIMPLEWORDS = "2345678wertyuipasdfghjkzxcvbnm2345678WERTYUPASDFGHJKLZXCVBNM";

        #region 私有對象
        const string ONE = "{0}";
        static RandomId _Rid = new RandomId(0);
        readonly static Random _Rand = new Random();
        static string ToFormat(int length)
        {
            StringBuilder sb = new StringBuilder(length * 3);
            for (int i = 0; i < length; i++)
            {
                sb.Append(ONE);
            }
            return sb.ToString();
        }

        readonly string _Dict;
        readonly int _RMax;
        readonly string _Format;
        #endregion

        /// <summary> 構造函數
        /// </summary>
        /// <param name="length">生成Id長度</param>
        /// <param name="dict">隨機字符字典,默認字典為0-9a-zA-Z</param>
        public RandomId(int length, string dict = ALLWORDS)
            : this(RandomId.ToFormat(length), dict)
        { }
        /// <summary> 構造函數
        /// </summary>
        /// <param name="format">生成Id格式</param>
        /// <param name="dict">隨機字符字典,默認字典為0-9a-zA-Z</param>
        public RandomId(string format, string dict = ALLWORDS)
        {
            _Dict = dict;
            _Format = format;
            _RMax = dict.Length;
        }

        /// <summary> 生成Id
        /// </summary>
        public string Create()
        {
            return string.Format(_Format, this);
        }
        /// <summary> 生成Id
        /// </summary>
        /// <param name="length">生成Id長度</param>
        /// <param name="dict">隨機字符字典,默認字典為0-9a-zA-Z</param>
        public static string Create(int length, string dict = ALLWORDS)
        {
            return new RandomId(length, dict).Create();
        }
        /// <summary> 生成Id
        /// </summary>
        /// <param name="format">生成Id格式</param>
        /// <param name="dict">隨機字符字典,默認字典為0-9a-zA-Z</param>
        public static string Create(string format, string dict = ALLWORDS)
        {
            return new RandomId(format, dict).Create();
        }

        #region IFormattable 成員

        string IFormattable.ToString(string format, IFormatProvider formatProvider)
        {
            return _Dict[_Rand.Next(0, _RMax)].ToString();
        }

        #endregion

       
    }
}

Console.WriteLine(RandomId.Create(4));//使用默認字典生成4位隨機字符串,默認字典中不包含l,1,O,0,q,9等容易混淆字符
Console.WriteLine(RandomId.Create(4, RandomId.ALLWORDS));//使用完整字典(0-9a-zA-Z),生成4位隨機字符
Console.WriteLine(RandomId.Create(10, "多少級開發和貸款撒了花費大量時間好快理發店撒嬌哦就開放了的撒酒阿克里福德就是卡看了就分開的世界里分開家里的事"));//使用指定中文字典,生成4位隨機字符
Console.WriteLine(RandomId.Create("SN:{0}{0}{0}{0}-{0}{0}{0}-{0}{0}{0}.{0}{0}", "123456abcdef"));//使用指定字典生成特定格式的隨機字符