我正在处理目录和文件的TreeView。用户可以选择一个文件或目录,然后对其进行操作。这要求我有一个方法,根据用户的选择执行不同的操作。
目前,我正在做这样的事情,以确定路径是文件还是目录:
bool bIsFile = false;
bool bIsDirectory = false;
try
{
string[] subfolders = Directory.GetDirectories(strFilePath);
bIsDirectory = true;
bIsFile = false;
}
catch(System.IO.IOException)
{
bIsFolder = false;
bIsFile = true;
}
我不禁觉得有更好的方法可以做到这一点!我希望找到一个标准的。net方法来处理这个问题,但我还没有能够这样做。是否存在这样的方法,如果不存在,确定路径是文件还是目录的最直接的方法是什么?
这是我所能想到的最好的Exists和Attributes属性的行为:
using System.IO;
public static class FileSystemInfoExtensions
{
/// <summary>
/// Checks whether a FileInfo or DirectoryInfo object is a directory, or intended to be a directory.
/// </summary>
/// <param name="fileSystemInfo"></param>
/// <returns></returns>
public static bool IsDirectory(this FileSystemInfo fileSystemInfo)
{
if (fileSystemInfo == null)
{
return false;
}
if ((int)fileSystemInfo.Attributes != -1)
{
// if attributes are initialized check the directory flag
return fileSystemInfo.Attributes.HasFlag(FileAttributes.Directory);
}
// If we get here the file probably doesn't exist yet. The best we can do is
// try to judge intent. Because directories can have extensions and files
// can lack them, we can't rely on filename.
//
// We can reasonably assume that if the path doesn't exist yet and
// FileSystemInfo is a DirectoryInfo, a directory is intended. FileInfo can
// make a directory, but it would be a bizarre code path.
return fileSystemInfo is DirectoryInfo;
}
}
下面是测试结果:
[TestMethod]
public void IsDirectoryTest()
{
// non-existing file, FileAttributes not conclusive, rely on type of FileSystemInfo
const string nonExistentFile = @"C:\TotallyFakeFile.exe";
var nonExistentFileDirectoryInfo = new DirectoryInfo(nonExistentFile);
Assert.IsTrue(nonExistentFileDirectoryInfo.IsDirectory());
var nonExistentFileFileInfo = new FileInfo(nonExistentFile);
Assert.IsFalse(nonExistentFileFileInfo.IsDirectory());
// non-existing directory, FileAttributes not conclusive, rely on type of FileSystemInfo
const string nonExistentDirectory = @"C:\FakeDirectory";
var nonExistentDirectoryInfo = new DirectoryInfo(nonExistentDirectory);
Assert.IsTrue(nonExistentDirectoryInfo.IsDirectory());
var nonExistentFileInfo = new FileInfo(nonExistentDirectory);
Assert.IsFalse(nonExistentFileInfo.IsDirectory());
// Existing, rely on FileAttributes
const string existingDirectory = @"C:\Windows";
var existingDirectoryInfo = new DirectoryInfo(existingDirectory);
Assert.IsTrue(existingDirectoryInfo.IsDirectory());
var existingDirectoryFileInfo = new FileInfo(existingDirectory);
Assert.IsTrue(existingDirectoryFileInfo.IsDirectory());
// Existing, rely on FileAttributes
const string existingFile = @"C:\Windows\notepad.exe";
var existingFileDirectoryInfo = new DirectoryInfo(existingFile);
Assert.IsFalse(existingFileDirectoryInfo.IsDirectory());
var existingFileFileInfo = new FileInfo(existingFile);
Assert.IsFalse(existingFileFileInfo.IsDirectory());
}
很晚才到这里,但我发现Nullable<Boolean>返回值相当难看- IsDirectory(字符串路径)返回null并不等于没有详细注释的不存在的路径,所以我提出了以下内容:
public static class PathHelper
{
/// <summary>
/// Determines whether the given path refers to an existing file or directory on disk.
/// </summary>
/// <param name="path">The path to test.</param>
/// <param name="isDirectory">When this method returns, contains true if the path was found to be an existing directory, false in all other scenarios.</param>
/// <returns>true if the path exists; otherwise, false.</returns>
/// <exception cref="ArgumentNullException">If <paramref name="path"/> is null.</exception>
/// <exception cref="ArgumentException">If <paramref name="path"/> equals <see cref="string.Empty"/></exception>
public static bool PathExists(string path, out bool isDirectory)
{
if (path == null) throw new ArgumentNullException(nameof(path));
if (path == string.Empty) throw new ArgumentException("Value cannot be empty.", nameof(path));
isDirectory = Directory.Exists(path);
return isDirectory || File.Exists(path);
}
}
这个helper方法写得足够冗长和简洁,以便在第一次阅读时就能理解其意图。
/// <summary>
/// Example usage of <see cref="PathExists(string, out bool)"/>
/// </summary>
public static void Usage()
{
const string path = @"C:\dev";
if (!PathHelper.PathExists(path, out var isDirectory))
return;
if (isDirectory)
{
// Do something with your directory
}
else
{
// Do something with your file
}
}