using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;

namespace DataLoader.CS
{
    public class MD5Helper
    {
        /// <summary>
        /// 文件MD5校验
        /// </summary>
        /// <param name="pathName">文件绝对路径</param>
        /// <returns>MD5校验码</returns>
        public static string GetMD5Hash(string pathName)
        {
            try
            {
                FileStream oFileStream = new FileStream(pathName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                MD5CryptoServiceProvider oMD5Hasher = new MD5CryptoServiceProvider();
                byte[] arrbytHashValue = oMD5Hasher.ComputeHash(oFileStream); // 计算指定Stream 对象的哈希值
                oFileStream.Close();

                // 由以连字符分隔的十六进制对构成的String，其中每一对表示value 中对应的元素；例如“F-2C-4A”
                string strHashData = BitConverter.ToString(arrbytHashValue);

                return strHashData.Replace("-", "").ToLower(); // 替换-
            }
            catch (Exception ex)
            {
                return "";
            }
        }

        /// <summary>
        /// 字节数组校验
        /// </summary>
        /// <param name="buffer">待字节数组</param>
        /// <returns>MD5校验码</returns>
        public static string GetMD5Hash(byte[] buffer)
        {
            MD5CryptoServiceProvider oMD5Hasher = new MD5CryptoServiceProvider();
            try
            {
                // 计算指定Stream 对象的哈希值，由以连字符分隔的十六进制对构成的String，其中每一对表示value 中对应的元素；例如“F-2C-4A”
                byte[] arrbytHashValue = oMD5Hasher.ComputeHash(buffer);
                string strHashData = BitConverter.ToString(arrbytHashValue);

                return strHashData.Replace("-", "").ToLower(); // 替换-
            }
            catch (Exception ex)
            {
                return "";
            }
        }
    }
}