如何判断文件是否在占用？

使用托管方法来实现。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;
using System.IO;

namespace ALU.C0370A.SimuDID.Common
{
    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);

        //Judge whether the file is handled by process now
            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;
        }  
    }
}

测试代码：

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();  
    }  
}  

结果如下：