Question

我正在创建一个备份应用程序，其中c＃扫描目录。在我使用这样的东西之前，为了获取目录中的所有文件和子文件：

DirectoryInfo di = new DirectoryInfo("A:\\");
var directories= di.GetFiles("*", SearchOption.AllDirectories);

foreach (FileInfo d in directories)
{
       //Add files to a list so that later they can be compared to see if each file
       // needs to be copid or not
}

唯一的问题是，有时无法访问文件，我会收到几个错误。我得到的错误示例是： error

结果我创建了一个递归方法，它将扫描当前目录中的所有文件。如果该目录中有目录，那么将再次调用该方法传递该目录。关于这个方法的好处是我可以将文件放在try catch块中，如果没有错误，可以选择将这些文件添加到List中，如果我有错误，可以将目录添加到另一个列表。

try
{
    files = di.GetFiles(searchPattern, SearchOption.TopDirectoryOnly);               
}
catch
{
     //info of this folder was not able to get
     lstFilesErrors.Add(sDir(di));
     return;
}

所以这个方法效果很好唯一的问题是当我扫描一个大目录时需要很多次。我怎么能加快这个过程？我的实际方法是这样，以防你需要它。

private void startScan(DirectoryInfo di)
{
    //lstFilesErrors is a list of MyFile objects
    // I created that class because I wanted to store more specific information
    // about a file such as its comparePath name and other properties that I need 
    // in order to compare it with another list

    // lstFiles is a list of MyFile objects that store all the files
    // that are contained in path that I want to scan

    FileInfo[] files = null;
    DirectoryInfo[] directories = null;
    string searchPattern = "*.*";

    try
    {
        files = di.GetFiles(searchPattern, SearchOption.TopDirectoryOnly);               
    }
    catch
    {
        //info of this folder was not able to get
        lstFilesErrors.Add(sDir(di));
        return;
    }

    // if there are files in the directory then add those files to the list
    if (files != null)
    {
        foreach (FileInfo f in files)
        {
            lstFiles.Add(sFile(f));
        }
    }


    try
    {
        directories = di.GetDirectories(searchPattern, SearchOption.TopDirectoryOnly);
    }
    catch
    {
        lstFilesErrors.Add(sDir(di));
        return;
    }

    // if that directory has more directories then add them to the list then 
    // execute this function
    if (directories != null)
        foreach (DirectoryInfo d in directories)
        {
            FileInfo[] subFiles = null;
            DirectoryInfo[] subDir = null;

            bool isThereAnError = false;

            try
            {
                subFiles = d.GetFiles();
                subDir = d.GetDirectories();

            }
            catch
            {
                isThereAnError = true;                                                
            }

            if (isThereAnError)
                lstFilesErrors.Add(sDir(d));
            else
            {
                lstFiles.Add(sDir(d));
                startScan(d);
            }


        }

}

如果我尝试用以下方法处理异常，请解决此问题：

DirectoryInfo di = new DirectoryInfo("A:\\");
FileInfo[] directories = null;
            try
            {
                directories = di.GetFiles("*", SearchOption.AllDirectories);

            }
            catch (UnauthorizedAccessException e)
            {
                Console.WriteLine("There was an error with UnauthorizedAccessException");
            }
            catch
            {
                Console.WriteLine("There was antother error");
            }

如果发生异常，那么我就没有文件。

Answer 1

这种方法要快得多。您只能在将大量文件放入目录时进行通信。我的A：\外部硬盘包含近1太比特，因此在处理大量文件时会产生很大的不同。

static void Main(string[] args)
{
    DirectoryInfo di = new DirectoryInfo("A:\\");
    FullDirList(di, "*");
    Console.WriteLine("Done");
    Console.Read();
}

static List<FileInfo> files = new List<FileInfo>();  // List that will hold the files and subfiles in path
static List<DirectoryInfo> folders = new List<DirectoryInfo>(); // List that hold direcotries that cannot be accessed
static void FullDirList(DirectoryInfo dir, string searchPattern)
{
    // Console.WriteLine("Directory {0}", dir.FullName);
    // list the files
    try
    {
        foreach (FileInfo f in dir.GetFiles(searchPattern))
        {
            //Console.WriteLine("File {0}", f.FullName);
            files.Add(f);                    
        }
    }
    catch
    {
        Console.WriteLine("Directory {0}  \n could not be accessed!!!!", dir.FullName);                
        return;  // We alredy got an error trying to access dir so dont try to access it again
    }

    // process each directory
    // If I have been able to see the files in the directory I should also be able 
    // to look at its directories so I dont think I should place this in a try catch block
    foreach (DirectoryInfo d in dir.GetDirectories())
    {
        folders.Add(d);
        FullDirList(d, searchPattern);                    
    }

}

顺便说一下，感谢你的评论Jim Mischel

Answer 2

在.NET 4.0中，Directory.EnumerateFiles方法返回IEnumerable<string>并且未加载内存中的所有文件。只有在您开始迭代返回的集合时，才会返回文件并exceptions could be handled。

Answer 3

.NET文件枚举方法的历史很长。问题是没有一种枚举大型目录结构的即时方法。即使是这里接受的答案也存在GC分配的问题。

我能够做的最好的事情就是包含在我的库中，并在FindFile命名空间中显示为source（CSharpTest.Net.IO）类。此类可以枚举文件和文件夹，而无需不必要的GC分配和字符串编组。

用法很简单，RaiseOnAccessDenied属性将跳过用户无权访问的目录和文件：

    private static long SizeOf(string directory)
    {
        var fcounter = new CSharpTest.Net.IO.FindFile(directory, "*", true, true, true);
        fcounter.RaiseOnAccessDenied = false;

        long size = 0, total = 0;
        fcounter.FileFound +=
            (o, e) =>
            {
                if (!e.IsDirectory)
                {
                    Interlocked.Increment(ref total);
                    size += e.Length;
                }
            };

        Stopwatch sw = Stopwatch.StartNew();
        fcounter.Find();
        Console.WriteLine("Enumerated {0:n0} files totaling {1:n0} bytes in {2:n3} seconds.",
                          total, size, sw.Elapsed.TotalSeconds);
        return size;
    }

对于我的本地C：\驱动器，它输出以下内容：

枚举810,046个文件，总计307,707,792,662字节，232.876秒。

您的里程可能因驱动器速度而异，但这是我发现的在托管代码中枚举文件的最快方法。 event参数是FindFile.FileFoundEventArgs类型的变异类，所以请确保不要保留对它的引用，因为它的值会随着每个引发的事件而改变。

Answer 4

您可以使用它来获取所有目录和子目录。然后只需循环处理文件。

string[] folders = System.IO.Directory.GetDirectories(@"C:\My Sample Path\","*", System.IO.SearchOption.AllDirectories);

foreach(string f in folders)
{
   //call some function to get all files in folder
}

Answer 5

（在你的另一个问题中从我的其他答案复制了这篇文章）

Show progress when searching all files in a directory

快速文件枚举

当然，正如您已经知道的那样，有许多方法可以自己进行枚举......但没有一种方法可以瞬间完成。您可以尝试使用文件系统的USN Journal进行扫描。看看CodePlex中的这个项目：MFT Scanner in VB.NET ...它在不到15秒的时间内找到了我的IDE SATA（而不是SSD）驱动器中的所有文件，并找到了311000个文件。

您必须按路径过滤文件，以便仅返回您正在查看的路径中的文件。但这是工作的简单部分！

Answer 6

我知道这是旧的，但是......另一种选择可能是像这样使用FileSystemWatcher：

void SomeMethod()
{
    System.IO.FileSystemWatcher m_Watcher = new System.IO.FileSystemWatcher();
    m_Watcher.Path = path;
    m_Watcher.Filter = "*.*";
    m_Watcher.NotifyFilter = m_Watcher.NotifyFilter = NotifyFilters.LastAccess | NotifyFilters.LastWrite | NotifyFilters.FileName | NotifyFilters.DirectoryName;
    m_Watcher.Created += new FileSystemEventHandler(OnChanged);
    m_Watcher.EnableRaisingEvents = true;
}

private void OnChanged(object sender, FileSystemEventArgs e)
    {
        string path = e.FullPath;

        lock (listLock)
        {
            pathsToUpload.Add(path);
        }
    }

这将允许您使用极其轻量级的进程来查看文件更改的目录，然后您可以使用它来存储已更改的文件的名称，以便您可以在适当的时间备份它们。

Answer 7

也许它会对你有所帮助。您可以使用“DirectoryInfo.EnumerateFiles”方法并根据需要处理 UnauthorizedAccessException 。

using System;
using System.IO;

class Program
{
    static void Main(string[] args)
    {
        DirectoryInfo diTop = new DirectoryInfo(@"d:\");
        try
        {
            foreach (var fi in diTop.EnumerateFiles())
            {
                try
                {
                    // Display each file over 10 MB; 
                    if (fi.Length > 10000000)
                    {
                        Console.WriteLine("{0}\t\t{1}", fi.FullName, fi.Length.ToString("N0"));
                    }
                }
                catch (UnauthorizedAccessException UnAuthTop)
                {
                    Console.WriteLine("{0}", UnAuthTop.Message);
                }
            }

            foreach (var di in diTop.EnumerateDirectories("*"))
            {
                try
                {
                    foreach (var fi in di.EnumerateFiles("*", SearchOption.AllDirectories))
                    {
                        try
                        {
                            // Display each file over 10 MB; 
                            if (fi.Length > 10000000)
                            {
                                Console.WriteLine("{0}\t\t{1}",  fi.FullName, fi.Length.ToString("N0"));
                            }
                        }
                        catch (UnauthorizedAccessException UnAuthFile)
                        {
                            Console.WriteLine("UnAuthFile: {0}", UnAuthFile.Message);
                        }
                    }
                }
                catch (UnauthorizedAccessException UnAuthSubDir)
                {
                    Console.WriteLine("UnAuthSubDir: {0}", UnAuthSubDir.Message);
                }
            }
        }
        catch (DirectoryNotFoundException DirNotFound)
        {
            Console.WriteLine("{0}", DirNotFound.Message);
        }
        catch (UnauthorizedAccessException UnAuthDir)
        {
            Console.WriteLine("UnAuthDir: {0}", UnAuthDir.Message);
        }
        catch (PathTooLongException LongPath)
        {
            Console.WriteLine("{0}", LongPath.Message);
        }
    }
}

快速获取特定路径中的所有文件和目录

7 个答案:

快速文件枚举