C# FileShare类代码示例

        public static void Lock(string path, int millisecondsTimeout, Action<FileStream> action,
            FileMode mode, FileAccess access, FileShare share)
        {
            var log = Program.Log;
            var autoResetEvent = new AutoResetEvent(false);

            const string pattern = "Lock('{0}', {1}, {2}, {3}, {4})";
            string msg = string.Format(pattern, path, millisecondsTimeout, mode, access, share);
            log.Trace(msg);

            while (true)
            {
                try
                {
                    using (var stream = File.Open(path, mode, access, share))
                    {
                        const string pattern2 = "Access to file: {0}, {1}, {2}, {3}";
                        string msg2 = string.Format(pattern2, path, mode, access, share);
                        log.Trace(msg2);

                        action(stream);
                        break;
                    }
                }
                catch (IOException exc)
                {
                    const string pattern3 = "Cannot access to file: {0}";
                    string msg3 = string.Format(pattern3, path);
                    log.TraceException(msg3, exc);

                    AutoResetFileSystemWatcher(path, millisecondsTimeout, autoResetEvent);
                }
            }
        }

        /// <summary>
        /// Pass the file handle to the <see cref="System.IO.FileStream"/> constructor. 
        /// The <see cref="System.IO.FileStream"/> will close the handle.
        /// </summary>
        public static SafeFileHandle CreateFileHandle(
			string filePath,
			CreationDisposition creationDisposition,
			FileAccess fileAccess,
			FileShare fileShare)
        {
            filePath = CheckAddLongPathPrefix(filePath);

            // Create a file with generic write access
            var fileHandle =
                PInvokeHelper.CreateFile(
                    filePath,
                    fileAccess,
                    fileShare,
                    IntPtr.Zero,
                    creationDisposition,
                    0,
                    IntPtr.Zero);

            // Check for errors.
            var lastWin32Error = Marshal.GetLastWin32Error();
            if (fileHandle.IsInvalid)
            {
                throw new Win32Exception(
                    lastWin32Error,
                    string.Format(
                        "Error {0} creating file handle for file path '{1}': {2}",
                        lastWin32Error,
                        filePath,
                        CheckAddDotEnd(new Win32Exception(lastWin32Error).Message)));
            }

            // Pass the file handle to FileStream. FileStream will close the handle.
            return fileHandle;
        }

 public static extern SafeFileHandle CreateFile(String fileName,
     FileAccess desiredAccess,
     FileShare shareMode,
     IntPtr securityAttrs,
     FileMode creationDisposition,
     int flagsAndAttributes,
     IntPtr templateFile);

		public static FileStream OpenSequentialStream(string path, FileMode mode, FileAccess access, FileShare share)
		{
			var options = FileOptions.SequentialScan;

			if (concurrency > 0)
			{
				options |= FileOptions.Asynchronous;
			}

#if MONO
			return new FileStream( path, mode, access, share, bufferSize, options );
            #else
			if (unbuffered)
			{
				options |= NoBuffering;
			}
			else
			{
				return new FileStream(path, mode, access, share, bufferSize, options);
			}

			SafeFileHandle fileHandle = CreateFile(path, (int)access, share, IntPtr.Zero, mode, (int)options, IntPtr.Zero);

			if (fileHandle.IsInvalid)
			{
				throw new IOException();
			}

			return new UnbufferedFileStream(fileHandle, access, bufferSize, (concurrency > 0));
#endif
		}

		static internal string ToString(string path, FileMode mode, FileAccess access, FileShare share)
		{
			// http://ee.php.net/fopen

			//'r'  	 Open for reading only; place the file pointer at the beginning of the file.
			//'r+' 	Open for reading and writing; place the file pointer at the beginning of the file.
			//'w' 	Open for writing only; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.
			//'w+' 	Open for reading and writing; place the file pointer at the beginning of the file and truncate the file to zero length. If the file does not exist, attempt to create it.
			//'a' 	Open for writing only; place the file pointer at the end of the file. If the file does not exist, attempt to create it.
			//'a+' 	Open for reading and writing; place the file pointer at the end of the file. If the file does not exist, attempt to create it.
			//'x' 	Create and open for writing only; place the file pointer at the beginning of the file. If the file already exists, the fopen() call will fail by returning FALSE and generating an error of level E_WARNING. If the file does not exist, attempt to create it. This is equivalent to specifying O_EXCL|O_CREAT flags for the underlying open(2) system call.
			//'x+' 	Create and open for reading and writing; place the file pointer at the beginning of the file. If the file already exists, the fopen() call will fail by returning FALSE and generating an error of level E_WARNING. If the file does not exist, attempt to create it. This is equivalent to specifying O_EXCL|O_CREAT flags for the underlying open(2) system call. 

			if (mode == FileMode.OpenOrCreate)
			{
				if (access == FileAccess.Write)
				{
					if (File.Exists(path))
						return "r+b";
					else
						return "x+b";
				}

				if (access == FileAccess.Read)
				{
					if (File.Exists(path))
						return "rb";
					else
						return "xb";
				}
			}

			var e = new { mode, access, share };
			throw new NotImplementedException(e.ToString());
		}

 /// <summary>
 /// Check's if the file has the accessrights specified in the input parameters
 /// </summary>
 /// <param name="filename"></param>
 /// <param name="fa">Read,Write,ReadWrite</param>
 /// <param name="fs">Read,ReadWrite...</param>
 /// <returns></returns>
 public static void CheckFileAccessRights(string fileName, FileMode fm, FileAccess fa, FileShare fs)
 {
   FileStream fileStream = null;
   StreamReader streamReader = null;
   try
   {
     Encoding fileEncoding = Encoding.Default;
     fileStream = File.Open(fileName, fm, fa, fs);
     streamReader = new StreamReader(fileStream, fileEncoding, true);
   }
   finally
   {
     try
     {
       if (fileStream != null)
       {
         fileStream.Close();
         fileStream.Dispose();
       }
       if (streamReader != null)
       {
         streamReader.Close();
         streamReader.Dispose();
       }
     }
     finally {}
   }
 }

 internal LogStream(string path, int bufferSize, LogRetentionOption retention, long maxFileSize, int maxNumOfFiles)
 {
     string fullPath = Path.GetFullPath(path);
     this._fileName = fullPath;
     if (fullPath.StartsWith(@"\\.\", StringComparison.Ordinal))
     {
         throw new NotSupportedException(System.SR.GetString("NotSupported_IONonFileDevices"));
     }
     Microsoft.Win32.UnsafeNativeMethods.SECURITY_ATTRIBUTES secAttrs = GetSecAttrs(FileShare.Read);
     int num = 0x100000;
     this._canWrite = true;
     this._pathSav = fullPath;
     this._fAccessSav = 0x40000000;
     this._shareSav = FileShare.Read;
     this._secAttrsSav = secAttrs;
     this._secAccessSav = FileIOPermissionAccess.Write;
     this._modeSav = (retention != LogRetentionOption.SingleFileUnboundedSize) ? FileMode.Create : FileMode.OpenOrCreate;
     this._flagsAndAttributesSav = num;
     this._seekToEndSav = retention == LogRetentionOption.SingleFileUnboundedSize;
     base.bufferSize = bufferSize;
     this._retention = retention;
     this._maxFileSize = maxFileSize;
     this._maxNumberOfFiles = maxNumOfFiles;
     this._Init(fullPath, this._fAccessSav, this._shareSav, this._secAttrsSav, this._secAccessSav, this._modeSav, this._flagsAndAttributesSav, this._seekToEndSav);
 }

        public static Stream CreateFile(
            string fileName, FileAccess fileAccess, FileShare fileShare, FileMode fileMode, FileAttributes flags)
        {
            // TODO: This is not quite right, but it's close.
            //
            var nativeAccess = fileAccess;
            if ((nativeAccess & FileAccess.Read) != 0)
            {
                nativeAccess &= ~FileAccess.Read;
                nativeAccess |= (FileAccess)GENERIC_READ;
            }
            if ((nativeAccess & FileAccess.Write) != 0)
            {
                nativeAccess &= ~FileAccess.Write;
                nativeAccess |= (FileAccess)GENERIC_WRITE;
            }

            var handle = _CreateFile(fileName, nativeAccess, fileShare, IntPtr.Zero, fileMode, flags, IntPtr.Zero);
            if (handle.IsInvalid)
            {
                Marshal.ThrowExceptionForHR(Marshal.GetHRForLastWin32Error());
            }

            return new SimpleFileStream(handle);
        }

 private static extern IntPtr CreateFile(string fileName, 
     FILE_ACCESS_RIGHTS access,
     FileShare share,
     int securityAttributes,
     FileMode creation,
     FILE_FLAGS flags,
     IntPtr templateFile);

 private static extern SafeFileHandle CreateFile(string filename,
                                FileAccess desiredAccess,
                                FileShare shareMode,
                                IntPtr attributes,
                                FileMode creationDisposition,
                                uint flagsAndAttributes = 0,
                                IntPtr templateFile = default(IntPtr));

		public Stream FileOpen(string filePath, FileMode fileMode, FileAccess fileAccess, FileShare fileShare)
		{
#if WINDOWS_STORE_APP
			var folder = ApplicationData.Current.LocalFolder;
			if (fileMode == FileMode.Create || fileMode == FileMode.CreateNew)
			{
				return folder.OpenStreamForWriteAsync(filePath, CreationCollisionOption.ReplaceExisting).GetAwaiter().GetResult();
			}
			else if (fileMode == FileMode.OpenOrCreate)
			{
				if (fileAccess == FileAccess.Read)
					return folder.OpenStreamForReadAsync(filePath).GetAwaiter().GetResult();
				else
				{
					// Not using OpenStreamForReadAsync because the stream position is placed at the end of the file, instead of the beginning
					var f = folder.CreateFileAsync(filePath, CreationCollisionOption.OpenIfExists).AsTask().GetAwaiter().GetResult();
					return f.OpenAsync(FileAccessMode.ReadWrite).AsTask().GetAwaiter().GetResult().AsStream();
				}
			}
			else if (fileMode == FileMode.Truncate)
			{
				return folder.OpenStreamForWriteAsync(filePath, CreationCollisionOption.ReplaceExisting).GetAwaiter().GetResult();
			}
			else
			{
				//if (fileMode == FileMode.Append)
				// Not using OpenStreamForReadAsync because the stream position is placed at the end of the file, instead of the beginning
				folder.CreateFileAsync(filePath, CreationCollisionOption.OpenIfExists).AsTask().GetAwaiter().GetResult().OpenAsync(FileAccessMode.ReadWrite).AsTask().GetAwaiter().GetResult().AsStream();
				var f = folder.CreateFileAsync(filePath, CreationCollisionOption.OpenIfExists).AsTask().GetAwaiter().GetResult();
				return f.OpenAsync(FileAccessMode.ReadWrite).AsTask().GetAwaiter().GetResult().AsStream();
			}
#else
			return File.Open(filePath, fileMode, fileAccess, fileShare);
#endif
		}

        /// <summary>
        /// Opens a <see cref="FileStream"/> 
        /// </summary>
        /// <param name="path">The file to open. </param>
        /// <param name="mode"><see cref="FileMode"/></param>
        /// <param name="access"><see cref="FileAccess"/></param>
        /// <param name="share"><see cref="FileShare"/> </param>
        /// <returns>A <see cref="FileStream"/></returns>
        /// <remarks>http://msdn.microsoft.com/en-us/library/y973b725(v=vs.110).aspx</remarks>
        public static FileStream Open( string path, FileMode mode, FileAccess access, FileShare share )
        {
            Contract.Requires( !String.IsNullOrWhiteSpace( path ) );
            Contract.Ensures( Contract.Result<FileStream>() != null );

            return OpenFileStream( path, access, mode, share );
        }

        public override Stream OpenInputFileStream(string path, FileMode mode, FileAccess access, FileShare share)
        {
            //TODO: OpenInputFileStream with params

            Stream st = null;
            if (access == FileAccess.Read)
            {
                st = OpenInputFileStream(path);
                if (st == null)
                {
                    CRhoFile file = new CRhoFile();
                    file.open(path, CRhoFile.EOpenModes.OpenReadOnly);
                    st = file.getStream();
                }

            }
            else
            {
                CRhoFile file = new CRhoFile();
                file.open(path, CRhoFile.EOpenModes.OpenForReadWrite);
                st = file.getStream();
            }

            return st;
        }

 public SeqFileStreamReader(string fn, FileMode mode, FileAccess access, FileShare share, int bufferSize)
     : base(fn, mode, access, share, bufferSize)
 {
     curfilename = fn;
     bufsz = bufferSize;
     _init();
 }

	public IsolatedStorageFileStream(String path, FileMode mode,
									 FileAccess access, FileShare share,
									 int bufferSize)
			: this(path, mode, access, share, bufferSize, null)
			{
				// Nothing to do here.
			}