对于应用程序，有时候可能需要判断某个文件是否已经被打开，也就是指是否被某个流连接着。这在对文件的读写比较频繁的程序中尤为重要，因为一个文件同一时刻只能有一个流连接的。下面的代码也许能有所帮助。

public class FileStatus      {          [DllImport("kernel32.dll")]          private static extern IntPtr _lopen(string lpPathName, int iReadWrite);            [DllImport("kernel32.dll")]          private static extern bool CloseHandle(IntPtr hObject);            private const int OF_READWRITE = 2;            private const int OF_SHARE_DENY_NONE = 0x40;            private static readonly IntPtr HFILE_ERROR = new IntPtr(-1);            public static int FileIsOpen(string fileFullName)          {              if (!File.Exists(fileFullName))              {                  return -1;              }                IntPtr handle = _lopen(fileFullName, OF_READWRITE | OF_SHARE_DENY_NONE);                if (handle == HFILE_ERROR)              {                  return 1;              }                CloseHandle(handle);                return 0;          }      }

测试：

class Program      {          static void Main(string[] args)          {              string testFilePath = AppDomain.CurrentDomain.SetupInformation.ApplicationBase + @"testOpen.txt";                FileStream fs = new FileStream(testFilePath, FileMode.OpenOrCreate, FileAccess.Read);                BinaryReader br = new BinaryReader(fs);                br.Read();                Console.WriteLine("文件被打开");                int result =FileStatus.FileIsOpen(testFilePath);                Console.WriteLine(result);                br.Close();                Console.WriteLine("文件被关闭");                result = FileStatus.FileIsOpen(testFilePath);                Console.WriteLine(result);                Console.ReadLine();          }      }

结果：

代码下载：