/// <summary>
        /// 文件是否被占用
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public static bool IsFileInUse(string fileName)
        {
            bool inUse = true;

            FileStream fs = null;
            try
            {

                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.None);

                inUse = false;
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex);
                inUse = false;
            }
            finally
            {
                if (fs != null)

                    fs.Close();
            }
            return inUse;//true表示正在使用,false没有使用
        }

这个能解除占用问题

private const int OF_READWRITE = 2;
        private const int OF_SHARE_DENY_NONE = 0x40;
        private static readonly IntPtr HFILE_ERROR = new IntPtr(-1);
        /// <summary>
        /// 关闭文件句柄
        /// </summary>
        /// <param name="hObject"></param>
        /// <returns></returns>
        [DllImport("kernel32.dll")]
        private static extern bool CloseHandle(IntPtr hObject);
        /// <summary>
        /// 判断文件是否打开
        /// </summary>
        /// <param name="lpPathName">文件名称</param>
        /// <param name="iReadWrite"></param>
        /// <returns></returns>
        [DllImport("kernel32.dll")]
        private static extern IntPtr _lopen(string lpPathName, int iReadWrite);
        public static bool IsFileInUse(string fileName)
        {
            bool inUse = true;
            FileStream fs = null;
            try
            {
                fs = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.None);
                inUse = false;
            }
            catch
            {
                IntPtr vHandle = _lopen(fileName, OF_READWRITE | OF_SHARE_DENY_NONE);
                CloseHandle(vHandle);
            }
            finally
            {
                if (fs != null)
                    fs.Close();
            }
            return inUse;//true表示正在使用,false没有使用  
        }