C#判斷檔案是否被開啟佔用

C#判斷檔案是否被開啟佔用using System.IO;using System.Runtime.InteropServices;[DllImport("kernel32.dll")]public static extern IntPtr _lopen(string lpPathName, int iReadWrite);[DllImport("kernel32.dll")]public static extern bool CloseHandle(IntPtr hObject);public const int OF_READWRITE = 2;public const int OF_SHARE_DENY_NONE = 0x40;public readonly IntPtr HFILE_ERROR = new IntPtr(-1);private void button1_Click(object sender, EventArgs e){    string vFileName = @"c:\temp\temp.bmp";    if (!File.Exists(vFileName))    {        MessageBox.Show("檔案都不存在，你就不要拿來耍了");        return;    }    IntPtr vHandle = _lopen(vFileName, OF_READWRITE | OF_SHARE_DENY_NONE);    if (vHandle == HFILE_ERROR)    {        MessageBox.Show("檔案被佔用！");        return;    }    CloseHandle(vHandle);    MessageBox.Show("沒有被佔用！");}