using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Data;
using System.Data.OleDb;
using System.Text.RegularExpressions;
using System.Configuration;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Security.Cryptography;
using System.Globalization;
public class Unitl 
{
#region 验证是否是数字
        /// <summary>
        /// 验证是否是数字
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        public static bool IsNumeric(string str)
        {
            if (str == null || str.Length == 0)
                return false;
            System.Text.ASCIIEncoding ascii = new System.Text.ASCIIEncoding();
            byte[] bytestr = ascii.GetBytes(str);
            foreach (byte c in bytestr)
            {
                if (c < 48 || c > 57)
                {
                    return false;
                }
            }
            return true;
        }
        #endregion

        #region 生成随机数.
        static int iseed = 0;
        /// <summary> 
        /// 生成数字和字母随机数.
        /// </summary> 
        /// <param name="n">生成长度</param> 
        /// <returns></returns> 
        public static string RandCode(int nLeng)
        {
            char[] arrChar = new char[]{ 
            '0','1','2','3','4','5','6','7','8','9', 
            'a','b','c','d','e','f','g','h','i','j','k','m','n','p','q','r','s','t','u','v','w','x','y','z' ,
            'A','B','C','D','E','F','G','H','J','K','L','M','N','P','Q','R','S','T','U','V','W','X','Y','Z'
        };
            StringBuilder num = new StringBuilder();
            iseed++;
            iseed = iseed % 10000;
            Random rnd = new Random(iseed);
            for (int i = 0; i < nLeng; i++)
            {
                num.Append(arrChar[rnd.Next(0, arrChar.Length)].ToString());
            }
            return num.ToString();
        }

        /// <summary> 
        /// 生成数字和字母随机数 .
        /// </summary> 
        /// <param name="n">生成长度</param> 
        /// <returns></returns> 
        public static string RandCode(string RCstr, int nLeng)
        {
            StringBuilder num = new StringBuilder();
            Random rnd = new Random(DateTime.Now.Millisecond);
            for (int i = 0; i < nLeng; i++)
            {
                num.Append(RCstr[rnd.Next(0, RCstr.Length)].ToString());
            }
            return num.ToString();
        }

        /// <summary>
        /// 生成按当前日期串组成的字符串.
        /// </summary>
        /// <param name="fileExtName"></param>
        /// <returns></returns>
        public static string RandFileName(string fileExtName)
        {
            return string.Format("{0}{1}{2}", DateTime.Now.ToString("yyyyMMddhhmmss"), RandCode(8), fileExtName);
        }

        #endregion

        #region md5加密
        /// <summary>
        /// 对字符串进行MD5加密.
        /// </summary>
        /// <param name="str"></param>
        /// <returns></returns>
        public static string Md5(string str)
        {
            return Md5(str, "utf-8");
        }
        /// <summary>
        /// MD5加密.
        /// </summary>
        /// <param name="str"></param>
        /// <param name="charset"></param>
        /// <returns></returns>
        public static string Md5(string str, string charset)
        {
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] t = md5.ComputeHash(Encoding.GetEncoding(charset).GetBytes(str));
            StringBuilder sb = new StringBuilder(32);
            for (int i = 0; i < t.Length; i++)
            {
                sb.Append(t[i].ToString("x").PadLeft(2, '0'));
            }
            return sb.ToString();