Question

var fsw = new FileSystemWatcher(sPath, "*.PPF");
fsw.NotifyFilter = NotifyFilters.FileName;
fsw.IncludeSubdirectories = true;
fsw.Created += FswCreated;
fsw.EnableRaisingEvents = true;

static void FswCreated(object sender, FileSystemEventArgs e)
{
  string sFile = e.FullPath;
  string[] arrLines = File.ReadAllLines(sFile);
}

这会因大文件而失败，因为编写文件时没有完成该过程。该文件是通过网络复制的，所以我不知道文件的大小。需要什么样的同步才能使其稳健？

Answer 1

在stackoverflow上找到解决方案并对其进行了一些修改。

static bool IsFileLocked(FileInfo file)
{
    FileStream stream = null;

    try
    {
        stream = file.Open(FileMode.Open, 
                 FileAccess.ReadWrite, FileShare.None);
    }
    catch (IOException)
    {
        //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;
}

static void FswCreated(object sender, FileSystemEventArgs e)
{
    string sFile = e.FullPath;

    Console.WriteLine("processing file : " + sFile);

    // Wait if file is still open
    FileInfo fileInfo = new FileInfo(sFile);
    while(IsFileLocked(fileInfo))
    {
        Thread.Sleep(500);
    }

    string[] arrLines = File.ReadAllLines(sFile);
}

Answer 2

使用DelayedFileSystemWatcher.cs班级http://blogs.msdn.com/b/ahamza/archive/2006/02/06/526222.aspx

然后是这段代码。检查PrintFileSystemEventHandler事件处理程序。它尝试在文件流中读取文件，如果有任何错误，则假定文件仍在读取，因此它等待一段时间（本例中为2秒），然后再次尝试。查看CONVERSION:标签

static void Main(string[] args)
    {
        DelayedFileSystemWatcher dfw = new DelayedFileSystemWatcher(@"C:\\Test", "*.*");
        dfw.Changed += new FileSystemEventHandler(Program.FileSystemEventHandlerMethod);
        dfw.Created += new FileSystemEventHandler(Program.FileSystemEventHandlerMethod);
        dfw.Deleted += new FileSystemEventHandler(Program.FileSystemEventHandlerMethod);
        dfw.Error += new ErrorEventHandler(Program.ErrorEventHandlerMethod);
        dfw.Renamed += new RenamedEventHandler(Program.RenamedEventHandlerMethod);

        dfw.IncludeSubdirectories = true;
        dfw.ConsolidationInterval = 1000;
        dfw.EnableRaisingEvents = true;
        Console.WriteLine("Press \'q\' to quit the sample.");
        while (Console.Read() != 'q') ;
        //System.Threading.Thread.Sleep(60000);
        dfw.Dispose();
    }
    private static void FileSystemEventHandlerMethod(object sender, FileSystemEventArgs e)
    {
        PrintFileSystemEventHandler(e);
        System.Console.WriteLine();
    }

    private static void ErrorEventHandlerMethod(object sender, ErrorEventArgs e)
    {
        System.Console.WriteLine(e.GetException().Message);
        System.Console.WriteLine();
    }

    private static void RenamedEventHandlerMethod(object sender, RenamedEventArgs e)
    {
        PrintRenamedEventHandler(e);
        System.Console.WriteLine();
    }

    private static void PrintFileSystemEventHandler(FileSystemEventArgs e)
    {

    CONVERSION:
        try
        {

            if (e.ChangeType != WatcherChangeTypes.Deleted)
            {
                if (!isFolder(e.FullPath) && isFile(e.FullPath))
                {
                    FileStream fs = new FileStream(e.FullPath, FileMode.Open, FileAccess.Read, FileShare.None);
                    fs.Close();
                }

            }
            System.Console.WriteLine(e.Name + " " + e.FullPath + " " + e.ChangeType);

        }
        catch (System.IO.IOException)
        {
            Console.WriteLine("There was an IOException error or File is still copying. Retrying in 2 seconds...");
            System.Threading.Thread.Sleep(2000);
            goto CONVERSION;
        }



        //System.Console.WriteLine(e.Name);
        //System.Console.WriteLine(e.FullPath);
        //System.Console.WriteLine(e.ChangeType);
    }

    private static bool isFolder(string strPath)
    {

        bool isFolderExist = false;
        try
        {
            isFolderExist = Directory.Exists(strPath);
        }
        catch
        {
            isFolderExist = false;
        }
        return isFolderExist;
    }

    private static bool isFile(string strPath)
    {

        bool isFileExist = false;
        try
        {
            isFileExist = File.Exists(strPath);
        }
        catch
        {
            isFileExist = false;
        }
        return isFileExist;
    }


    private static void PrintRenamedEventHandler(RenamedEventArgs e)
    {
        PrintFileSystemEventHandler(e);
        System.Console.WriteLine(e.OldName);
        System.Console.WriteLine(e.OldFullPath);
    }

我没有该项目的链接。但这将有所帮助。

Answer 3

我支持Shay Erlichmen接受的解决方案。但无论如何 a）您可能不想以访问模式FileAccess.Read打开文件，请将其作为只读文件

b）有些程序在下载时，文件会有一些有趣的扩展名，完成后，扩展名会发生变化，虽然文件已经完成，但你会发现文件未找到异常。

因此处理异常，并订阅file.renamed事件

Answer 4

AFAIK复制完成后，您不会收到通知，您可以实施重试机制如果你受到剪切违规，只需触发计时器在X秒内重试操作第二次重试应该在X * 2秒之后，依此类推（当然有一些限制）。

Answer 5

只需在fswCreated中，如果可能，请使用Thread.Sleep(500)睡眠约1/2秒。这应该给你计算机完成文件编写所需的时间。

当然，对于较慢的硬盘驱动器，这可能或者可能有足够的时间。

文件系统观察程序和大文件

5 个答案: