获取有关文件、文件夹和驱动器的信息

在 .NET Framework 中，可以使用以下类来访问文件系统信息：

• System.IO.FileInfo

• System.IO.DirectoryInfo

• System.IO.DriveInfo

• System.IO.Directory

• System.IO.File

FileInfo 和 DirectoryInfo 类表示文件或目录，包含公开 NTFS 文件系统所支持的很多文件特性的属性， 同时还包含用于打开、关闭、移动和删除文件和文件夹的方法。 可以通过将表示文件、文件夹或驱动器名称的字符串传递到下面的构造函数来创建这些类的实例：

System.IO.DriveInfo di = new System.IO.DriveInfo(@"C:\"); 

此外，还可以通过调用 DirectoryInfo.GetDirectories、DirectoryInfo.GetFiles 和 DriveInfo.RootDirectory 来获取文件、文件夹或驱动器的名称。

System.IO.Directory 和 System.IO.File 类提供用于检索有关目录和文件的信息的静态方法。

下面的示例演示访问有关文件和文件夹的信息的各种方法。

class FileSysInfo
    {
        static void Main()
        {
            // You can also use System.Environment.GetLogicalDrives to
            // obtain names of all logical drives on the computer.
            System.IO.DriveInfo di = new System.IO.DriveInfo(@"C:\");
            Console.WriteLine(di.TotalFreeSpace);
            Console.WriteLine(di.VolumeLabel);

            // Get the root directory and print out some information about it.
            System.IO.DirectoryInfo dirInfo = di.RootDirectory;
            Console.WriteLine(dirInfo.Attributes.ToString());

            // Get the files in the directory and print out some information about them.
            System.IO.FileInfo[] fileNames = dirInfo.GetFiles("*.*");


            foreach (System.IO.FileInfo fi in fileNames)
            {
                Console.WriteLine("{0}: {1}: {2}", fi.Name, fi.LastAccessTime, fi.Length);
            }

            // Get the subdirectories directly that is under the root.
            // See "How to: Iterate Through a Directory Tree" for an example of how to
            // iterate through an entire tree.
            System.IO.DirectoryInfo[] dirInfos = dirInfo.GetDirectories("*.*");

            foreach (System.IO.DirectoryInfo d in dirInfos)
            {
                Console.WriteLine(d.Name);
            }

            // The Directory and File classes provide several static methods
            // for accessing files and directories.

            // Get the current application directory.
            string currentDirName = System.IO.Directory.GetCurrentDirectory();
            Console.WriteLine(currentDirName);           

            // Get an array of file names as strings rather than FileInfo objects.
            // Use this method when storage space is an issue, and when you might
            // hold on to the file name reference for a while before you try to access
            // the file.
            string[] files = System.IO.Directory.GetFiles(currentDirName, "*.txt");

            foreach (string s in files)
            {
                // Create the FileInfo object only when needed to ensure
                // the information is as current as possible.
                System.IO.FileInfo fi = null;
                try
                {
                     fi = new System.IO.FileInfo(s);
                }
                catch (System.IO.FileNotFoundException e)
                {
                    // To inform the user and continue is
                    // sufficient for this demonstration.
                    // Your application may require different behavior.
                    Console.WriteLine(e.Message);
                    continue;
                }
                Console.WriteLine("{0} : {1}",fi.Name, fi.Directory);
            }

            // Change the directory. In this case, first check to see
            // whether it already exists, and create it if it does not.
            // If this is not appropriate for your application, you can
            // handle the System.IO.IOException that will be raised if the
            // directory cannot be found.
            if (!System.IO.Directory.Exists(@"C:\Users\Public\TestFolder\"))
            {
                System.IO.Directory.CreateDirectory(@"C:\Users\Public\TestFolder\");
            }

            System.IO.Directory.SetCurrentDirectory(@"C:\Users\Public\TestFolder\");

            currentDirName = System.IO.Directory.GetCurrentDirectory();
            Console.WriteLine(currentDirName);

            // Keep the console window open in debug mode.
            Console.WriteLine("Press any key to exit.");
            Console.ReadKey();
        }
    }

处理用户指定的路径字符串时，还应处理在以下情况下引发的异常：

• 文件名的格式不正确。 例如，包含无效字符或仅包含空白。

• 文件名为空。

• 文件名长于系统定义的最大长度。

• 文件名包含冒号 (:)。

如果应用程序不具有读取指定文件所需的足够权限，则无论路径是否存在，Exists 方法都将返回 false；该方法不引发异常。