判斷檔案是否鎖定中

例如正在寫入中，檔案還不完整

public static bool IsFileLocked(this System.IO.FileInfo file)

    {

        System.IO.FileStream stream = null;

        try

        {

            stream = file.Open(System.IO.FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.None);

        }

        catch 

        {

            //the file is unavailable because it is:

            //still being written to

            //or being processed by another thread

            //or does not exist (has already been processed)

            return true;

        }

        finally

        {

            if (stream != null)

                stream.Close();

        }

        //file is not locked

        return false;

    }