using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.IO;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace FileToMD5
{
    public partial class Form_MD5 : Form
    {
        public Form_MD5()
        {
            InitializeComponent();
        }

        private void btn_md5_Click(object sender, EventArgs e)
        {
            OpenFileDialog ofd = new OpenFileDialog();
            ofd.InitialDirectory = "D:\\";
            try
            {
                if (ofd.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                {
                    txtFilePath.Text = ofd.FileName;
                    //创建一个文件对象
                    FileInfo EzoneFile = new FileInfo(txtFilePath.Text);
                    //打开文件流
                    FileStream EzoneStream = EzoneFile.OpenRead();
                    //EzoneStream.Position = 0;
                    long size = EzoneStream.Length;
                    byte[] array = new byte[size];//文件
                    EzoneStream.Read(array, 0, array.Length);
                    string md5 = GetMD5HashFromFile(array);
                    txtMd5.Text = md5;
                    EzoneStream.Close();
                    EzoneStream = null;
                    EzoneFile = null;
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
           
        }

        public static string GetMD5HashFromFile(byte[] filedatas)
        {
            try
            {
                System.Security.Cryptography.MD5 md5 = new System.Security.Cryptography.MD5CryptoServiceProvider();
                byte[] retVal = md5.ComputeHash(filedatas);
                StringBuilder sb = new StringBuilder();
                for (int i = 0; i < retVal.Length; i++)
                {
                    sb.Append(retVal[i].ToString("x2"));
                }
                return sb.ToString();
            }
            catch (Exception ex)
            {
                //errorinfo = ex.Message.ToString();
                return "";
            }
        }
    }
}