HOW TO:取得有關檔案、資料夾和磁碟機的資訊 (C# 程式設計手冊)
在 .NET Framework 中,您可以使用下列類別 (Class) 存取檔案系統資訊:
FileInfo 和 DirectoryInfo 類別表示檔案或目錄,而包含的屬性 (Property) 可公開 NTFS 檔案系統支援的許多檔案屬性 (Attribute)。 這兩個類別也包含可用來開啟、關閉、移動和刪除檔案及資料夾的方法。 只要將表示檔案、資料夾或磁碟機的名稱傳遞給建構函式 (Constructor),就可以建立這些類別的執行個體 (Instance)。
System.IO.DriveInfo di = new System.IO.DriveInfo(@"C:\");
您還可以呼叫 DirectoryInfo.GetDirectories、DirectoryInfo.GetFiles 和 DriveInfo.RootDirectory,取得檔案、資料夾或磁碟機的名稱。
System.IO.Directory 和 System.IO.File 類別提供的靜態 (Static) 方法可用來擷取目錄及檔案的相關資訊。
範例
在下列範例中,會示範各種方法來存取檔案和資料夾的相關資訊。
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();
}
}
穩固程式設計
處理使用者指定的路徑字串時,也必須處理下列情形的例外狀況 (Exception):
檔案名稱格式不正確, 例如包含無效字元或只有泛空白字元 (White Space)。
檔案名稱為 null。
檔案名稱長度超過系統定義的最大長度。
檔案名稱包含冒號 (:)。
如果應用程式沒有足夠的權限可以讀取指定的檔案,則無論路徑是否存在,Exists 方法都會傳回 false,此方法並不會擲回例外狀況。