C#文件相同性判断

 /// <summary>
        /// 获取文件的绝对路径,针对window程序和web程序都可使用
        /// </summary>
        /// <param name="relativePath">相对路径地址</param>
        /// <returns>绝对路径地址</returns>
        public static string GetAbsolutePath(string relativePath)
        {
            if (string.IsNullOrEmpty(relativePath))
            {
                throw new ArgumentNullException("参数relativePath空异常！");
            }
            relativePath = relativePath.Replace("/", "\\");
            if (relativePath[0] == '\\')
            {
                relativePath=relativePath.Remove(0, 1);
            }
            //判断是Web程序还是window程序
            if (HttpContext.Current != null)
            {
                return Path.Combine(HttpRuntime.AppDomainAppPath, relativePath);
            }
            else
            {
                return Path.Combine(AppDomain.CurrentDomain.BaseDirectory, relativePath);
            }
        }

 /// <summary>
        /// 获取文件的绝对路径,针对window程序和web程序都可使用
        /// </summary>
        /// <param name="relativePath">相对路径地址</param>
        /// <returns>绝对路径地址</returns>
        public static string GetRootPath()
        {
            //判断是Web程序还是window程序
            if (HttpContext.Current != null)
            {
                return HttpRuntime.AppDomainAppPath;
            }
            else
            {
                return AppDomain.CurrentDomain.BaseDirectory;
            }
        }

  /// <summary>
        /// 通过文件Hash 比较两个文件内容是否相同
        /// </summary>
        /// <param name="filePath1">文件1地址</param>
        /// <param name="filePath2">文件2地址</param>
        /// <returns></returns>
        public static bool isValidFileContent(string filePath1, string filePath2)
        {
            //创建一个哈希算法对象 
            using (HashAlgorithm hash = HashAlgorithm.Create())
            {
                using (FileStream file1 = new FileStream(filePath1, FileMode.Open), file2 = new FileStream(filePath2, FileMode.Open))
                {
                    byte[] hashByte1 = hash.ComputeHash(file1);//哈希算法根据文本得到哈希码的字节数组 
                    byte[] hashByte2 = hash.ComputeHash(file2);
                    string str1 = BitConverter.ToString(hashByte1);//将字节数组装换为字符串 
                    string str2 = BitConverter.ToString(hashByte2);
                    return (str1 == str2);//比较哈希码 
                }
            }
        }

 /// <summary>
        /// 计算文件的hash值 用于比较两个文件是否相同
        /// </summary>
        /// <param name="filePath">文件路径</param>
        /// <returns>文件hash值</returns>
        public static string GetFileHash(string filePath)
        {
            //创建一个哈希算法对象 
            using (HashAlgorithm hash = HashAlgorithm.Create())
            {
                using (FileStream file = new FileStream(filePath, FileMode.Open))
                {
                    //哈希算法根据文本得到哈希码的字节数组 
                    byte[] hashByte= hash.ComputeHash(file);
                    //将字节数组装换为字符串  
                    return BitConverter.ToString(hashByte);
                }
            }
        }