实现MD5算法

using System;
using System.Text;
using System.Security.Cryptography;

namespace Common
{
    /// <summary>
    /// 一个实现MD5散列字符串的类
    /// 作者：周公
    /// 日期：2007
    /// </summary>
    public sealed class MD5Hashing
    {
        private static MD5 md5 = MD5.Create();
        //私有化构造函数
        private MD5Hashing()
        {
        }
        /// <summary>
        /// 使用utf8编码将字符串散列
        /// </summary>
        /// <param name="sourceString">要散列的字符串</param>
        /// <returns>散列后的字符串</returns>
       public static string HashString(string sourceString)
       {
            return HashString(Encoding.UTF8, sourceString);
       }
       /// <summary>
       /// 使用指定的编码将字符串散列
       /// </summary>
       /// <param name="encode">编码</param>
       /// <param name="sourceString">要散列的字符串</param>
       /// <returns>散列后的字符串</returns>
        public static string HashString(Encoding encode, string sourceString)
        {
            byte[] source = md5.ComputeHash(encode.GetBytes(sourceString));
            StringBuilder sBuilder = new StringBuilder();
            for (int i = 0; i < source.Length; i++)
            {
                sBuilder.Append(source[i].ToString("x2"));
            }
            return sBuilder.ToString();
        }
    }
}