162

我需要在目录中找到最近修改的文件。

我知道我可以遍历文件夹中的每个文件并进行比较File.GetLastWriteTime，但是有没有更好的方法可以在不循环的情况下做到这一点？

4

11 回答 11

353

像这样的东西怎么样...

var directory = new DirectoryInfo("C:\\MyDirectory");
var myFile = (from f in directory.GetFiles()
             orderby f.LastWriteTime descending
             select f).First();

// or...
var myFile = directory.GetFiles()
             .OrderByDescending(f => f.LastWriteTime)
             .First();
于 2009-07-24T20:25:44.627 回答
29

扩展上面的第一个，如果您想搜索某个模式，您可以使用以下代码：

using System.IO;
using System.Linq;
...
string pattern = "*.txt";
var dirInfo = new DirectoryInfo(directory);
var file = (from f in dirInfo.GetFiles(pattern) orderby f.LastWriteTime descending select f).First();
于 2012-07-11T02:20:49.233 回答
20

如果你想递归搜索，你可以使用这段漂亮的代码：

public static FileInfo GetNewestFile(DirectoryInfo directory) {
   return directory.GetFiles()
       .Union(directory.GetDirectories().Select(d => GetNewestFile(d)))
       .OrderByDescending(f => (f == null ? DateTime.MinValue : f.LastWriteTime))
       .FirstOrDefault();                        
}

只需按以下方式调用它：

FileInfo newestFile = GetNewestFile(new DirectoryInfo(@"C:\directory\"));

就是这样。如果目录为空，则返回一个FileInfo实例。null

于 2011-04-24T03:55:59.310 回答
10

非 LINQ 版本：

/// <summary>
/// Returns latest writen file from the specified directory.
/// If the directory does not exist or doesn't contain any file, DateTime.MinValue is returned.
/// </summary>
/// <param name="directoryInfo">Path of the directory that needs to be scanned</param>
/// <returns></returns>
private static DateTime GetLatestWriteTimeFromFileInDirectory(DirectoryInfo directoryInfo)
{
    if (directoryInfo == null || !directoryInfo.Exists)
        return DateTime.MinValue;

    FileInfo[] files = directoryInfo.GetFiles();
    DateTime lastWrite = DateTime.MinValue;

    foreach (FileInfo file in files)
    {
        if (file.LastWriteTime > lastWrite)
        {
            lastWrite = file.LastWriteTime;
        }
    }

    return lastWrite;
}

/// <summary>
/// Returns file's latest writen timestamp from the specified directory.
/// If the directory does not exist or doesn't contain any file, null is returned.
/// </summary>
/// <param name="directoryInfo">Path of the directory that needs to be scanned</param>
/// <returns></returns>
private static FileInfo GetLatestWritenFileFileInDirectory(DirectoryInfo directoryInfo)
{
    if (directoryInfo == null || !directoryInfo.Exists)
        return null;

    FileInfo[] files = directoryInfo.GetFiles();
    DateTime lastWrite = DateTime.MinValue;
    FileInfo lastWritenFile = null;

    foreach (FileInfo file in files)
    {
        if (file.LastWriteTime > lastWrite)
        {
            lastWrite = file.LastWriteTime;
            lastWritenFile = file;
        }
    }
    return lastWritenFile;
}
于 2009-11-23T07:51:11.310 回答
7

简短而简单：

new DirectoryInfo(path).GetFiles().OrderByDescending(o => o.LastWriteTime).FirstOrDefault();
于 2017-08-13T01:46:45.523 回答
4

Directory.EnumerateFiles如果您正在使用并希望读取最新修改的文​​件，则另一种方法是首先。

foreach (string file in Directory.EnumerateFiles(fileDirectory, fileType).OrderByDescending(f => new FileInfo(f).LastWriteTime))

}
于 2018-06-28T06:21:08.390 回答
3

您可以使用FileSystemWatcher对新文件活动做出反应。

于 2009-07-24T20:25:17.267 回答
3

有点晚了，但是……

您的代码将无法正常工作，因为list<FileInfo> lastUpdateFile = null; 以后lastUpdatedFile.Add(file);会抛出 NullReference 异常。工作版本应该是：

private List<FileInfo> GetLastUpdatedFileInDirectory(DirectoryInfo directoryInfo)
{
    FileInfo[] files = directoryInfo.GetFiles();
    List<FileInfo> lastUpdatedFile = new List<FileInfo>();
    DateTime lastUpdate = DateTime.MinValue;
    foreach (FileInfo file in files)
    {
        if (file.LastAccessTime > lastUpdate)
        {
            lastUpdatedFile.Add(file);
            lastUpdate = file.LastAccessTime;
        }
    }

    return lastUpdatedFile;
}

谢谢

于 2014-05-27T19:58:58.993 回答
2

这是一个从每个子目录中获取最新文件的版本

List<string> reports = new List<string>();    
DirectoryInfo directory = new DirectoryInfo(ReportsRoot);
directory.GetFiles("*.xlsx", SearchOption.AllDirectories).GroupBy(fl => fl.DirectoryName)
.ForEach(g => reports.Add(g.OrderByDescending(fi => fi.LastWriteTime).First().FullName));
于 2013-09-09T15:19:35.933 回答
0 
private List<FileInfo> GetLastUpdatedFileInDirectory(DirectoryInfo directoryInfo)
{
    FileInfo[] files = directoryInfo.GetFiles();
    List<FileInfo> lastUpdatedFile = null;
    DateTime lastUpdate = new DateTime(1, 0, 0);
    foreach (FileInfo file in files)
    {
        if (file.LastAccessTime > lastUpdate)
        {
            lastUpdatedFile.Add(file);
            lastUpdate = file.LastAccessTime;
        }
    }

    return lastUpdatedFile;
}
于 2012-02-07T07:48:12.303 回答
0

我这样做是一堆我的应用程序，我使用这样的声明：

  var inputDirectory = new DirectoryInfo("\\Directory_Path_here");
  var myFile = inputDirectory.GetFiles().OrderByDescending(f => f.LastWriteTime).First();

从这里您将在“inputDirectory”变量的目录中获得最近保存/添加/更新的文件的文件名。现在你可以访问它并用它做你想做的事。

希望有帮助。

于 2016-02-23T18:55:38.697 回答