C#下获取文件的MD5值

using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Text;using System.Windows.Forms;using System.Security.Cryptography;using System.IO;using System.Reflection;namespace Get_File_MD5_Value{    public partial class Form1 : Form    {        public Form1()        {            InitializeComponent();        }        private void Form1_Load(object sender, EventArgs e)        {        }        /// <summary>        /// 计算文件的 MD5 值        /// </summary>        /// <param name="fileName">要计算 MD5 值的文件名和路径</param>        /// <returns>MD5 值16进制字符串</returns>        public string MD5File(string fileName)        {            return HashFile(fileName, "md5");        }        /// <summary>        /// 计算文件的 sha1 值        /// </summary>        /// <param name="fileName">要计算 sha1 值的文件名和路径</param>        /// <returns>sha1 值16进制字符串</returns>        public string SHA1File(string fileName)        {            return HashFile(fileName, "sha1");        }        /// <summary>        /// 计算文件的哈希值        /// </summary>        /// <param name="fileName">要计算哈希值的文件名和路径</param>        /// <param name="algName">算法:sha1,md5</param>        /// <returns>哈希值16进制字符串</returns>        private string HashFile(string fileName, string algName)        {            if (!System.IO.File.Exists(fileName))                return string.Empty;            System.IO.FileStream fs = new System.IO.FileStream(fileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);            byte[] hashBytes = HashData(fs, algName);            fs.Close();            return ByteArrayToHexString(hashBytes);        }        /// <summary>        /// 计算哈希值        /// </summary>        /// <param name="stream">要计算哈希值的 Stream</param>        /// <param name="algName">算法:sha1,md5</param>        /// <returns>哈希值字节数组</returns>        private byte[] HashData(System.IO.Stream stream, string algName)        {            System.Security.Cryptography.HashAlgorithm algorithm;            if (algName == null)            {                throw new ArgumentNullException("algName 不能为 null");            }            if (string.Compare(algName, "sha1", true) == 0)            {                algorithm = System.Security.Cryptography.SHA1.Create();            }            else            {                if (string.Compare(algName, "md5", true) != 0)                {                    throw new Exception("algName 只能使用 sha1 或 md5");                }                algorithm = System.Security.Cryptography.MD5.Create();            }            return algorithm.ComputeHash(stream);        }        /// <summary>        /// 字节数组转换为16进制表示的字符串        /// </summary>        private string ByteArrayToHexString(byte[] buf)        {            return BitConverter.ToString(buf).Replace("-", "");        }        private void Btn_File_Click(object sender, EventArgs e)        {            OpenFileDialog openFileDialog = new OpenFileDialog();            openFileDialog.InitialDirectory = System.Environment.CurrentDirectory;            openFileDialog.Filter = "所有文件|*.*";            openFileDialog.RestoreDirectory = true;            openFileDialog.FilterIndex = 1;            if (openFileDialog.ShowDialog() == DialogResult.OK)            {                this.Txt_FileSource.Text = openFileDialog.FileName;                this.Txt_MD5.Text= MD5File(openFileDialog.FileName);  //生成MD5值            }            else            {                return;            }        }           }}