我使用。net 3.5，试图递归删除目录使用:
Directory.Delete(myPath, true);
我的理解是，如果文件正在使用或存在权限问题，这应该抛出，但否则它应该删除目录及其所有内容。
然而，我偶尔会遇到这样的情况:
System.IO.IOException: The directory is not empty.
at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
at System.IO.Directory.DeleteHelper(String fullPath, String userPath, Boolean recursive)
at System.IO.Directory.Delete(String fullPath, String userPath, Boolean recursive)
...
我并不惊讶于这个方法有时会抛出错误，但我惊讶于当递归为真时得到这个特定的消息。(我知道目录不是空的。)
是否有一个原因，我将看到这个而不是AccessViolationException?
现代异步回答
公认的答案是完全错误的，它可能适用于某些人，因为从磁盘获取文件所花费的时间释放了锁定文件的任何东西。事实上，这是因为文件被其他进程/流/操作锁定了。其他答案使用Thread。Sleep (Yuck)在一段时间后重试删除目录。这个问题需要一个更现代的答案来重新审视。
public static async Task<bool> TryDeleteDirectory(
string directoryPath,
int maxRetries = 10,
int millisecondsDelay = 30)
{
if (directoryPath == null)
throw new ArgumentNullException(directoryPath);
if (maxRetries < 1)
throw new ArgumentOutOfRangeException(nameof(maxRetries));
if (millisecondsDelay < 1)
throw new ArgumentOutOfRangeException(nameof(millisecondsDelay));
for (int i = 0; i < maxRetries; ++i)
{
try
{
if (Directory.Exists(directoryPath))
{
Directory.Delete(directoryPath, true);
}
return true;
}
catch (IOException)
{
await Task.Delay(millisecondsDelay);
}
catch (UnauthorizedAccessException)
{
await Task.Delay(millisecondsDelay);
}
}
return false;
}
单元测试
这些测试展示了一个被锁定的文件如何导致目录的示例。删除失败以及上面的TryDeleteDirectory方法如何修复这个问题。
[Fact]
public async Task TryDeleteDirectory_FileLocked_DirectoryNotDeletedReturnsFalse()
{
var directoryPath = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
var subDirectoryPath = Path.Combine(Path.GetTempPath(), "SubDirectory");
var filePath = Path.Combine(directoryPath, "File.txt");
try
{
Directory.CreateDirectory(directoryPath);
Directory.CreateDirectory(subDirectoryPath);
using (var fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.Write))
{
var result = await TryDeleteDirectory(directoryPath, 3, 30);
Assert.False(result);
Assert.True(Directory.Exists(directoryPath));
}
}
finally
{
if (Directory.Exists(directoryPath))
{
Directory.Delete(directoryPath, true);
}
}
}
[Fact]
public async Task TryDeleteDirectory_FileLockedThenReleased_DirectoryDeletedReturnsTrue()
{
var directoryPath = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
var subDirectoryPath = Path.Combine(Path.GetTempPath(), "SubDirectory");
var filePath = Path.Combine(directoryPath, "File.txt");
try
{
Directory.CreateDirectory(directoryPath);
Directory.CreateDirectory(subDirectoryPath);
Task<bool> task;
using (var fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write, FileShare.Write))
{
task = TryDeleteDirectory(directoryPath, 3, 30);
await Task.Delay(30);
Assert.True(Directory.Exists(directoryPath));
}
var result = await task;
Assert.True(result);
Assert.False(Directory.Exists(directoryPath));
}
finally
{
if (Directory.Exists(directoryPath))
{
Directory.Delete(directoryPath, true);
}
}
}
当方法是异步的并像这样编码时，我解决了上述问题的一个可能实例:
// delete any existing update content folder for this update
if (await fileHelper.DirectoryExistsAsync(currentUpdateFolderPath))
await fileHelper.DeleteDirectoryAsync(currentUpdateFolderPath);
用这个:
bool exists = false;
if (await fileHelper.DirectoryExistsAsync(currentUpdateFolderPath))
exists = true;
// delete any existing update content folder for this update
if (exists)
await fileHelper.DeleteDirectoryAsync(currentUpdateFolderPath);
结论?去除用于检查存在的句柄有一些异步的方面，微软无法与之对话。这就好像if语句中的异步方法让if语句充当using语句一样。
