如何从路径和文件名中删除非法字符?

小开

首先，Trim仅从字符串的开头或结尾删除字符。其次，您应该评估是否真的想删除冒犯性字符，或者快速失败，让用户知道他们的文件名是无效的。我的选择是后者，但我的答案至少应该告诉你如何正确和错误地做事:

# EYZ0。注意，您可以使用这个问题中的regex使用正则表达式替换来删除字符(如果您确实需要这样做的话)。

小开

最佳答案

可以试试这样的方法;

string illegal = "\"M\"\\a/ry/ h**ad:>> a\\/:*?\"| li*tt|le|| la\"mb.?";
string invalid = new string(Path.GetInvalidFileNameChars()) + new string(Path.GetInvalidPathChars());


foreach (char c in invalid)
{
illegal = illegal.Replace(c.ToString(), "");
}

但我不得不同意这些评论，我可能会尝试处理非法路径的来源，而不是试图将非法路径破坏成合法但可能无意的路径。

编辑:或者一个潜在的“更好”的解决方案，使用正则表达式。

string illegal = "\"M\"\\a/ry/ h**ad:>> a\\/:*?\"| li*tt|le|| la\"mb.?";
string regexSearch = new string(Path.GetInvalidFileNameChars()) + new string(Path.GetInvalidPathChars());
Regex r = new Regex(string.Format("[{0}]", Regex.Escape(regexSearch)));
illegal = r.Replace(illegal, "");

不过，还是有个问题要问，你为什么要这么做。

小开

我认为使用正则表达式验证并指定允许哪些字符要容易得多，而不是试图检查所有坏字符。请看这些链接: http://www.c-sharpcorner.com/UploadFile/prasad_1/RegExpPSD12062005021717AM/RegExpPSD.aspx # EYZ0 < / p >

另外，搜索一下“正则表达式编辑器”，它们很有帮助。有一些甚至可以为你输出c#代码。

小开

我使用正则表达式来实现这一点。首先，我动态地构建正则表达式。

string regex = string.Format(
"[{0}]",
Regex.Escape(new string(Path.GetInvalidFileNameChars())));
Regex removeInvalidChars = new Regex(regex, RegexOptions.Singleline | RegexOptions.Compiled | RegexOptions.CultureInvariant);

然后我调用removeInvalidChars。替换来做查找和替换。这显然也可以扩展到覆盖路径字符。

小开

抛出异常。

if ( fileName.IndexOfAny(Path.GetInvalidFileNameChars()) > -1 )
{
throw new ArgumentException();
}

小开

下面的代码片段应该对。net 3及更高版本有所帮助。

using System.IO;
using System.Text.RegularExpressions;


public static class PathValidation
{
private static string pathValidatorExpression = "^[^" + string.Join("", Array.ConvertAll(Path.GetInvalidPathChars(), x => Regex.Escape(x.ToString()))) + "]+$";
private static Regex pathValidator = new Regex(pathValidatorExpression, RegexOptions.Compiled);


private static string fileNameValidatorExpression = "^[^" + string.Join("", Array.ConvertAll(Path.GetInvalidFileNameChars(), x => Regex.Escape(x.ToString()))) + "]+$";
private static Regex fileNameValidator = new Regex(fileNameValidatorExpression, RegexOptions.Compiled);


private static string pathCleanerExpression = "[" + string.Join("", Array.ConvertAll(Path.GetInvalidPathChars(), x => Regex.Escape(x.ToString()))) + "]";
private static Regex pathCleaner = new Regex(pathCleanerExpression, RegexOptions.Compiled);


private static string fileNameCleanerExpression = "[" + string.Join("", Array.ConvertAll(Path.GetInvalidFileNameChars(), x => Regex.Escape(x.ToString()))) + "]";
private static Regex fileNameCleaner = new Regex(fileNameCleanerExpression, RegexOptions.Compiled);


public static bool ValidatePath(string path)
{
return pathValidator.IsMatch(path);
}


public static bool ValidateFileName(string fileName)
{
return fileNameValidator.IsMatch(fileName);
}


public static string CleanPath(string path)
{
return pathCleaner.Replace(path, "");
}


public static string CleanFileName(string fileName)
{
return fileNameCleaner.Replace(fileName, "");
}
}

小开

你可以像这样使用Linq删除非法字符:

var invalidChars = Path.GetInvalidFileNameChars();


var invalidCharsRemoved = stringWithInvalidChars
.Where(x => !invalidChars.Contains(x))
.ToArray();

< p > # EYZ0 < br > 这是评论中提到的必要编辑后的样子:

var invalidChars = Path.GetInvalidFileNameChars();


string invalidCharsRemoved = new string(stringWithInvalidChars
.Where(x => !invalidChars.Contains(x))
.ToArray());

小开

我绝对更喜欢杰夫·耶茨的想法。它将完美地工作，如果你稍微修改它:

string regex = String.Format("[{0}]", Regex.Escape(new string(Path.GetInvalidFileNameChars())));
Regex removeInvalidChars = new Regex(regex, RegexOptions.Singleline | RegexOptions.Compiled | RegexOptions.CultureInvariant);

改进仅仅是转义自动生成的正则表达式。

小开

我使用Linq来清理文件名。您也可以很容易地扩展它来检查有效路径。

private static string CleanFileName(string fileName)
{
return Path.GetInvalidFileNameChars().Aggregate(fileName, (current, c) => current.Replace(c.ToString(), string.Empty));
}

更新

一些评论指出这个方法不适合他们，所以我包含了一个到DotNetFiddle片段的链接，这样你就可以验证这个方法了。

https://dotnetfiddle.net/nw1SWY

小开

这些都是很好的解决方案，但它们都依赖于Path.GetInvalidFileNameChars，它可能不像您想象的那么可靠。请注意MSDN文档中Path.GetInvalidFileNameChars的以下注释:

该方法返回的数组是不保证包含文件和目录名称中无效的完整字符集。无效字符的完整集可以因文件系统而异。例如，在基于windows的桌面平台上，无效路径字符可能包括ASCII/Unicode字符1到31，以及引号(")、小于(<)、大于(>)、管道(|)、退格(\b)、null(\0)和制表符(\t)。

使用Path.GetInvalidPathChars方法也好不到哪里去。它包含了完全相同的评论。

小开

上面的大多数解决方案都将路径和文件名的非法字符组合在一起，这是错误的(即使两个调用当前返回相同的字符集)。我将首先在path和filename中分割path+filename，然后应用适当的集，如果它们，然后再次结合两者。

wvd_vegt

小开

从用户输入中删除非法字符的最佳方法是使用Regex类替换非法字符，在代码后面创建方法，或者在客户端使用RegularExpression控件进行验证。

public string RemoveSpecialCharacters(string str)
{
return Regex.Replace(str, "[^a-zA-Z0-9_]+", "_", RegexOptions.Compiled);
}

或

<asp:RegularExpressionValidator ID="regxFolderName"
runat="server"
ErrorMessage="Enter folder name with  a-z A-Z0-9_"
ControlToValidate="txtFolderName"
Display="Dynamic"
ValidationExpression="^[a-zA-Z0-9_]*$"
ForeColor="Red">

小开

public static bool IsValidFilename(string testName)
{
return !new Regex("[" + Regex.Escape(new String(System.IO.Path.GetInvalidFileNameChars())) + "]").IsMatch(testName);
}

小开

我写这个怪物是为了好玩，它让你可以往返:

public static class FileUtility
{
private const char PrefixChar = '%';
private static readonly int MaxLength;
private static readonly Dictionary<char,char[]> Illegals;
static FileUtility()
{
List<char> illegal = new List<char> { PrefixChar };
illegal.AddRange(Path.GetInvalidFileNameChars());
MaxLength = illegal.Select(x => ((int)x).ToString().Length).Max();
Illegals = illegal.ToDictionary(x => x, x => ((int)x).ToString("D" + MaxLength).ToCharArray());
}


public static string FilenameEncode(string s)
{
var builder = new StringBuilder();
char[] replacement;
using (var reader = new StringReader(s))
{
while (true)
{
int read = reader.Read();
if (read == -1)
break;
char c = (char)read;
if(Illegals.TryGetValue(c,out replacement))
{
builder.Append(PrefixChar);
builder.Append(replacement);
}
else
{
builder.Append(c);
}
}
}
return builder.ToString();
}


public static string FilenameDecode(string s)
{
var builder = new StringBuilder();
char[] buffer = new char[MaxLength];
using (var reader = new StringReader(s))
{
while (true)
{
int read = reader.Read();
if (read == -1)
break;
char c = (char)read;
if (c == PrefixChar)
{
reader.Read(buffer, 0, MaxLength);
var encoded =(char) ParseCharArray(buffer);
builder.Append(encoded);
}
else
{
builder.Append(c);
}
}
}
return builder.ToString();
}


public static int ParseCharArray(char[] buffer)
{
int result = 0;
foreach (char t in buffer)
{
int digit = t - '0';
if ((digit < 0) || (digit > 9))
{
throw new ArgumentException("Input string was not in the correct format");
}
result *= 10;
result += digit;
}
return result;
}
}

小开

或者你可以这样做

[YOUR STRING].Replace('\\', ' ').Replace('/', ' ').Replace('"', ' ').Replace('*', ' ').Replace(':', ' ').Replace('?', ' ').Replace('<', ' ').Replace('>', ' ').Replace('|', ' ').Trim();

小开

文件名:

var cleanFileName = string.Join("", fileName.Split(Path.GetInvalidFileNameChars()));

对于全路径:

var cleanPath = string.Join("", path.Split(Path.GetInvalidPathChars()));

请注意，如果打算将此作为安全特性使用，更健壮的方法是展开所有路径，然后验证用户提供的路径确实是用户应该访问的目录的子目录。

小开

最初的问题是“去除非法字符”:

public string RemoveInvalidChars(string filename)
{
return string.Concat(filename.Split(Path.GetInvalidFileNameChars()));
}

相反，你可能想要替换它们:

public string ReplaceInvalidChars(string filename)
{
return string.Join("_", filename.Split(Path.GetInvalidFileNameChars()));
}

这个答案在谷神星的另一个帖子里，我真的很喜欢它的简洁。

小开

这样做会想要你想要的，避免碰撞

 static string SanitiseFilename(string key)
{
var invalidChars = Path.GetInvalidFileNameChars();
var sb = new StringBuilder();
foreach (var c in key)
{
var invalidCharIndex = -1;
for (var i = 0; i < invalidChars.Length; i++)
{
if (c == invalidChars[i])
{
invalidCharIndex = i;
}
}
if (invalidCharIndex > -1)
{
sb.Append("_").Append(invalidCharIndex);
continue;
}


if (c == '_')
{
sb.Append("__");
continue;
}


sb.Append(c);
}
return sb.ToString();


}

小开

如果你删除或替换一个字符无效字符，你可以有冲突:

<abc -> abc
>abc -> abc

这里有一个简单的方法来避免这种情况:

public static string ReplaceInvalidFileNameChars(string s)
{
char[] invalidFileNameChars = System.IO.Path.GetInvalidFileNameChars();
foreach (char c in invalidFileNameChars)
s = s.Replace(c.ToString(), "[" + Array.IndexOf(invalidFileNameChars, c) + "]");
return s;
}

结果:

 <abc -> [1]abc
>abc -> [2]abc

小开

这看起来是O(n)，并且不会在字符串上花费太多内存:

    private static readonly HashSet<char> invalidFileNameChars = new HashSet<char>(Path.GetInvalidFileNameChars());


public static string RemoveInvalidFileNameChars(string name)
{
if (!name.Any(c => invalidFileNameChars.Contains(c))) {
return name;
}


return new string(name.Where(c => !invalidFileNameChars.Contains(c)).ToArray());
}

小开

我认为这个问题还没有完全回答… 答案只描述干净的文件名或路径…不是两个。这是我的解决方案:

private static string CleanPath(string path)
{
string regexSearch = new string(Path.GetInvalidFileNameChars()) + new string(Path.GetInvalidPathChars());
Regex r = new Regex(string.Format("[{0}]", Regex.Escape(regexSearch)));
List<string> split = path.Split('\\').ToList();
string returnValue = split.Aggregate(string.Empty, (current, s) => current + (r.Replace(s, "") + @"\"));
returnValue = returnValue.TrimEnd('\\');
return returnValue;
}

小开

浏览这里的答案，它们似乎都涉及使用无效文件名字符的char数组。

当然，这可能是一种微观优化——但对于那些希望检查大量值是否为有效文件名的人来说，值得注意的是，构建一个由无效字符组成的哈希集将带来明显更好的性能。

过去，我对哈希集(或字典)比遍历列表的速度快得多感到非常惊讶。对于字符串，它是一个低得可笑的数字(从记忆中大约5-7项)。对于大多数其他简单数据(对象引用，数字等)，神奇的交叉似乎是大约20个项目。

路径中有40个无效字符。InvalidFileNameChars“列表”。今天搜索了一下，在StackOverflow上有一个很好的基准测试，显示hashset将花费40个数组/列表一半多一点的时间:https://stackoverflow.com/a/10762995/949129

下面是我用于清理路径的helper类。我现在忘记了为什么我在里面有漂亮的替换选项，但这是一个可爱的奖励。

额外的奖励方法“IsValidLocalPath”:)

(**那些不使用正则表达式的)

public static class PathExtensions
{
private static HashSet<char> _invalidFilenameChars;
private static HashSet<char> InvalidFilenameChars
{
get { return _invalidFilenameChars ?? (_invalidFilenameChars = new HashSet<char>(Path.GetInvalidFileNameChars())); }
}




/// <summary>Replaces characters in <c>text</c> that are not allowed in file names with the
/// specified replacement character.</summary>
/// <param name="text">Text to make into a valid filename. The same string is returned if
/// it is valid already.</param>
/// <param name="replacement">Replacement character, or NULL to remove bad characters.</param>
/// <param name="fancyReplacements">TRUE to replace quotes and slashes with the non-ASCII characters ” and ⁄.</param>
/// <returns>A string that can be used as a filename. If the output string would otherwise be empty, "_" is returned.</returns>
public static string ToValidFilename(this string text, char? replacement = '_', bool fancyReplacements = false)
{
StringBuilder sb = new StringBuilder(text.Length);
HashSet<char> invalids = InvalidFilenameChars;
bool changed = false;


for (int i = 0; i < text.Length; i++)
{
char c = text[i];
if (invalids.Contains(c))
{
changed = true;
char repl = replacement ?? '\0';
if (fancyReplacements)
{
if (c == '"') repl = '”'; // U+201D right double quotation mark
else if (c == '\'') repl = '’'; // U+2019 right single quotation mark
else if (c == '/') repl = '⁄'; // U+2044 fraction slash
}
if (repl != '\0')
sb.Append(repl);
}
else
sb.Append(c);
}


if (sb.Length == 0)
return "_";


return changed ? sb.ToString() : text;
}




/// <summary>
/// Returns TRUE if the specified path is a valid, local filesystem path.
/// </summary>
/// <param name="pathString"></param>
/// <returns></returns>
public static bool IsValidLocalPath(this string pathString)
{
// From solution at https://stackoverflow.com/a/11636052/949129
Uri pathUri;
Boolean isValidUri = Uri.TryCreate(pathString, UriKind.Absolute, out pathUri);
return isValidUri && pathUri != null && pathUri.IsLoopback;
}
}

小开

public static class StringExtensions
{
public static string RemoveUnnecessary(this string source)
{
string result = string.Empty;
string regex = new string(Path.GetInvalidFileNameChars()) + new string(Path.GetInvalidPathChars());
Regex reg = new Regex(string.Format("[{0}]", Regex.Escape(regex)));
result = reg.Replace(source, "");
return result;
}
}

你可以清楚地使用方法。

小开

我创建了一个扩展方法，它结合了几个建议:

在哈希集中保存非法字符
过滤ascii 127以下的字符。因为路径。getinvalidfilenamecars不包括ascii码从0到255的所有无效字符。在这里看到的和MSDN
定义替换字符的可能性

来源:

public static class FileNameCorrector
{
private static HashSet<char> invalid = new HashSet<char>(Path.GetInvalidFileNameChars());


public static string ToValidFileName(this string name, char replacement = '\0')
{
var builder = new StringBuilder();
foreach (var cur in name)
{
if (cur > 31 && cur < 128 && !invalid.Contains(cur))
{
builder.Append(cur);
}
else if (replacement != '\0')
{
builder.Append(replacement);
}
}


return builder.ToString();
}
}

小开

文件名不能包含Path.GetInvalidPathChars()， +和#符号中的字符，以及其他特定的名称。我们将所有检查合并到一个类中:

public static class FileNameExtensions
{
private static readonly Lazy<string[]> InvalidFileNameChars =
new Lazy<string[]>(() => Path.GetInvalidPathChars()
.Union(Path.GetInvalidFileNameChars()
.Union(new[] { '+', '#' })).Select(c => c.ToString(CultureInfo.InvariantCulture)).ToArray());




private static readonly HashSet<string> ProhibitedNames = new HashSet<string>
{
@"aux",
@"con",
@"clock$",
@"nul",
@"prn",


@"com1",
@"com2",
@"com3",
@"com4",
@"com5",
@"com6",
@"com7",
@"com8",
@"com9",


@"lpt1",
@"lpt2",
@"lpt3",
@"lpt4",
@"lpt5",
@"lpt6",
@"lpt7",
@"lpt8",
@"lpt9"
};


public static bool IsValidFileName(string fileName)
{
return !string.IsNullOrWhiteSpace(fileName)
&& fileName.All(o => !IsInvalidFileNameChar(o))
&& !IsProhibitedName(fileName);
}


public static bool IsProhibitedName(string fileName)
{
return ProhibitedNames.Contains(fileName.ToLower(CultureInfo.InvariantCulture));
}


private static string ReplaceInvalidFileNameSymbols([CanBeNull] this string value, string replacementValue)
{
if (value == null)
{
return null;
}


return InvalidFileNameChars.Value.Aggregate(new StringBuilder(value),
(sb, currentChar) => sb.Replace(currentChar, replacementValue)).ToString();
}


public static bool IsInvalidFileNameChar(char value)
{
return InvalidFileNameChars.Value.Contains(value.ToString(CultureInfo.InvariantCulture));
}


public static string GetValidFileName([NotNull] this string value)
{
return GetValidFileName(value, @"_");
}


public static string GetValidFileName([NotNull] this string value, string replacementValue)
{
if (string.IsNullOrWhiteSpace(value))
{
throw new ArgumentException(@"value should be non empty", nameof(value));
}


if (IsProhibitedName(value))
{
return (string.IsNullOrWhiteSpace(replacementValue) ? @"_" : replacementValue) + value;
}


return ReplaceInvalidFileNameSymbols(value, replacementValue);
}


public static string GetFileNameError(string fileName)
{
if (string.IsNullOrWhiteSpace(fileName))
{
return CommonResources.SelectReportNameError;
}


if (IsProhibitedName(fileName))
{
return CommonResources.FileNameIsProhibited;
}


var invalidChars = fileName.Where(IsInvalidFileNameChar).Distinct().ToArray();


if(invalidChars.Length > 0)
{
return string.Format(CultureInfo.CurrentCulture,
invalidChars.Length == 1 ? CommonResources.InvalidCharacter : CommonResources.InvalidCharacters,
StringExtensions.JoinQuoted(@",", @"'", invalidChars.Select(c => c.ToString(CultureInfo.CurrentCulture))));
}


return string.Empty;
}
}

方法GetValidFileName将所有错误数据替换为_。

小开

在windows文件命名中，使用一行程序清除字符串中的任何非法字符:

public static string CleanIllegalName(string p_testName) => new Regex(string.Format("[{0}]", Regex.Escape(new string(Path.GetInvalidFileNameChars()) + new string(Path.GetInvalidPathChars())))).Replace(p_testName, "");

小开

下面是一个用替换字符替换文件名中所有非法字符的函数:

public static string ReplaceIllegalFileChars(string FileNameWithoutPath, char ReplacementChar)
{
const string IllegalFileChars = "*?/\\:<>|\"";
StringBuilder sb = new StringBuilder(FileNameWithoutPath.Length);
char c;


for (int i = 0; i < FileNameWithoutPath.Length; i++)
{
c = FileNameWithoutPath[i];
if (IllegalFileChars.IndexOf(c) >= 0)
{
c = ReplacementChar;
}
sb.Append(c);
}
return (sb.ToString());
}

例如，下划线可以用作替换字符:

NewFileName = ReplaceIllegalFileChars(FileName, '_');

小开

这是我的一点小小的贡献。在同一字符串中替换而不创建新字符串或stringbuilder的方法。它快速，易于理解，是本文中所有提到的一个很好的选择。

private static HashSet<char> _invalidCharsHash;
private static HashSet<char> InvalidCharsHash
{
get { return _invalidCharsHash ?? (_invalidCharsHash = new HashSet<char>(Path.GetInvalidFileNameChars())); }
}


private static string ReplaceInvalidChars(string fileName, string newValue)
{
char newChar = newValue[0];


char[] chars = fileName.ToCharArray();
for (int i = 0; i < chars.Length; i++)
{
char c = chars[i];
if (InvalidCharsHash.Contains(c))
chars[i] = newChar;
}


return new string(chars);
}

你可以这样调用它:

string illegal = "\"M<>\"\\a/ry/ h**ad:>> a\\/:*?\"<>| li*tt|le|| la\"mb.?";
string legal = ReplaceInvalidChars(illegal);

并返回:

_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._

值得注意的是，该方法总是将无效字符替换为给定值，但不会删除它们。如果你想删除无效字符，这个替代方法可以做到:

private static string RemoveInvalidChars(string fileName, string newValue)
{
char newChar = string.IsNullOrEmpty(newValue) ? char.MinValue : newValue[0];
bool remove = newChar == char.MinValue;


char[] chars = fileName.ToCharArray();
char[] newChars = new char[chars.Length];
int i2 = 0;
for (int i = 0; i < chars.Length; i++)
{
char c = chars[i];
if (InvalidCharsHash.Contains(c))
{
if (!remove)
newChars[i2++] = newChar;
}
else
newChars[i2++] = c;


}


return new string(newChars, 0, i2);
}

基准

如果性能是你所追求的，我用这篇文章中发现的大多数方法执行了定时测试运行。其中一些方法不会替换为给定的char，因为OP要求清除字符串。我添加了用给定字符替换的测试，如果您的预期场景只需要删除不需要的字符，还添加了一些用空字符替换的测试。用于此基准测试的代码位于末尾，因此您可以运行自己的测试。

注:方法Test1和Test2都在本文中提出。

第一次运行

# EYZ0

结果:

============Test1===============
Elapsed=00:00:01.6665595
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test2===============
Elapsed=00:00:01.7526835
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test3===============
Elapsed=00:00:05.2306227
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test4===============
Elapsed=00:00:14.8203696
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test5===============
Elapsed=00:00:01.8273760
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test6===============
Elapsed=00:00:05.4249985
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test7===============
Elapsed=00:00:07.5653833
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test8===============
Elapsed=00:12:23.1410106
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test9===============
Elapsed=00:00:02.1016708
Result=_M ____a_ry_ h__ad___ a_________ li_tt_le__ la_mb._


============Test10===============
Elapsed=00:00:05.0987225
Result=M ary had a little lamb.


============Test11===============
Elapsed=00:00:06.8004289
Result=M ary had a little lamb.

第二次运行

# EYZ0

注意:Test1不会移除，只会替换。

结果:

============Test1===============
Elapsed=00:00:01.6945352
Result= M     a ry  h  ad    a          li tt le   la mb.


============Test2===============
Elapsed=00:00:01.4798049
Result=M ary had a little lamb.


============Test3===============
Elapsed=00:00:04.0415688
Result=M ary had a little lamb.


============Test4===============
Elapsed=00:00:14.3397960
Result=M ary had a little lamb.


============Test5===============
Elapsed=00:00:01.6782505
Result=M ary had a little lamb.


============Test6===============
Elapsed=00:00:04.9251707
Result=M ary had a little lamb.


============Test7===============
Elapsed=00:00:07.9562379
Result=M ary had a little lamb.


============Test8===============
Elapsed=00:12:16.2918943
Result=M ary had a little lamb.


============Test9===============
Elapsed=00:00:02.0770277
Result=M ary had a little lamb.


============Test10===============
Elapsed=00:00:05.2721232
Result=M ary had a little lamb.


============Test11===============
Elapsed=00:00:05.2802903
Result=M ary had a little lamb.

基准测试结果

方法Test1， Test2和Test5是最快的。方法Test8最慢。

代码

以下是基准测试的完整代码:

private static HashSet<char> _invalidCharsHash;
private static HashSet<char> InvalidCharsHash
{
get { return _invalidCharsHash ?? (_invalidCharsHash = new HashSet<char>(Path.GetInvalidFileNameChars())); }
}


private static string _invalidCharsValue;
private static string InvalidCharsValue
{
get { return _invalidCharsValue ?? (_invalidCharsValue = new string(Path.GetInvalidFileNameChars())); }
}


private static char[] _invalidChars;
private static char[] InvalidChars
{
get { return _invalidChars ?? (_invalidChars = Path.GetInvalidFileNameChars()); }
}


static void Main(string[] args)
{
string testPath = "\"M <>\"\\a/ry/ h**ad:>> a\\/:*?\"<>| li*tt|le|| la\"mb.?";


int max = 1000000;
string newValue = "";


TimeBenchmark(max, Test1, testPath, newValue);
TimeBenchmark(max, Test2, testPath, newValue);
TimeBenchmark(max, Test3, testPath, newValue);
TimeBenchmark(max, Test4, testPath, newValue);
TimeBenchmark(max, Test5, testPath, newValue);
TimeBenchmark(max, Test6, testPath, newValue);
TimeBenchmark(max, Test7, testPath, newValue);
TimeBenchmark(max, Test8, testPath, newValue);
TimeBenchmark(max, Test9, testPath, newValue);
TimeBenchmark(max, Test10, testPath, newValue);
TimeBenchmark(max, Test11, testPath, newValue);


Console.Read();
}


private static void TimeBenchmark(int maxLoop, Func<string, string, string> func, string testString, string newValue)
{
var sw = new Stopwatch();
sw.Start();
string result = string.Empty;


for (int i = 0; i < maxLoop; i++)
result = func?.Invoke(testString, newValue);


sw.Stop();


Console.WriteLine($"============{func.Method.Name}===============");
Console.WriteLine("Elapsed={0}", sw.Elapsed);
Console.WriteLine("Result={0}", result);
Console.WriteLine("");
}


private static string Test1(string fileName, string newValue)
{
char newChar = string.IsNullOrEmpty(newValue) ? char.MinValue : newValue[0];


char[] chars = fileName.ToCharArray();
for (int i = 0; i < chars.Length; i++)
{
if (InvalidCharsHash.Contains(chars[i]))
chars[i] = newChar;
}


return new string(chars);
}


private static string Test2(string fileName, string newValue)
{
char newChar = string.IsNullOrEmpty(newValue) ? char.MinValue : newValue[0];
bool remove = newChar == char.MinValue;


char[] chars = fileName.ToCharArray();
char[] newChars = new char[chars.Length];
int i2 = 0;
for (int i = 0; i < chars.Length; i++)
{
char c = chars[i];
if (InvalidCharsHash.Contains(c))
{
if (!remove)
newChars[i2++] = newChar;
}
else
newChars[i2++] = c;


}


return new string(newChars, 0, i2);
}


private static string Test3(string filename, string newValue)
{
foreach (char c in InvalidCharsValue)
{
filename = filename.Replace(c.ToString(), newValue);
}


return filename;
}


private static string Test4(string filename, string newValue)
{
Regex r = new Regex(string.Format("[{0}]", Regex.Escape(InvalidCharsValue)));
filename = r.Replace(filename, newValue);
return filename;
}


private static string Test5(string filename, string newValue)
{
return string.Join(newValue, filename.Split(InvalidChars));
}


private static string Test6(string fileName, string newValue)
{
return InvalidChars.Aggregate(fileName, (current, c) => current.Replace(c.ToString(), newValue));
}


private static string Test7(string fileName, string newValue)
{
string regex = string.Format("[{0}]", Regex.Escape(InvalidCharsValue));
return Regex.Replace(fileName, regex, newValue, RegexOptions.Compiled);
}


private static string Test8(string fileName, string newValue)
{
string regex = string.Format("[{0}]", Regex.Escape(InvalidCharsValue));
Regex removeInvalidChars = new Regex(regex, RegexOptions.Singleline | RegexOptions.Compiled | RegexOptions.CultureInvariant);
return removeInvalidChars.Replace(fileName, newValue);
}


private static string Test9(string fileName, string newValue)
{
StringBuilder sb = new StringBuilder(fileName.Length);
bool changed = false;


for (int i = 0; i < fileName.Length; i++)
{
char c = fileName[i];
if (InvalidCharsHash.Contains(c))
{
changed = true;
sb.Append(newValue);
}
else
sb.Append(c);
}


if (sb.Length == 0)
return newValue;


return changed ? sb.ToString() : fileName;
}


private static string Test10(string fileName, string newValue)
{
if (!fileName.Any(c => InvalidChars.Contains(c)))
{
return fileName;
}


return new string(fileName.Where(c => !InvalidChars.Contains(c)).ToArray());
}


private static string Test11(string fileName, string newValue)
{
string invalidCharsRemoved = new string(fileName
.Where(x => !InvalidChars.Contains(x))
.ToArray());


return invalidCharsRemoved;
}

小开

我已经滚动了我自己的方法，这似乎要快得多的其他张贴在这里(特别是正则表达式是如此缓慢)，但我没有测试所有张贴的方法。

https://dotnetfiddle.net/haIXiY

第一个方法(我的)和第二个方法(也是我的，但旧的)也对反斜杠进行了额外的检查，所以基准测试并不完美，但无论如何，这只是给你一个想法。

在我的笔记本电脑上的结果(10万次迭代):

StringHelper.RemoveInvalidCharacters 1: 451 ms
StringHelper.RemoveInvalidCharacters 2: 7139 ms
StringHelper.RemoveInvalidCharacters 3: 2447 ms
StringHelper.RemoveInvalidCharacters 4: 3733 ms
StringHelper.RemoveInvalidCharacters 5: 11689 ms  (==> Regex!)

最快的方法:

public static string RemoveInvalidCharacters(string content, char replace = '_', bool doNotReplaceBackslashes = false)
{
if (string.IsNullOrEmpty(content))
return content;


var idx = content.IndexOfAny(InvalidCharacters);
if (idx >= 0)
{
var sb = new StringBuilder(content);
while (idx >= 0)
{
if (sb[idx] != '\\' || !doNotReplaceBackslashes)
sb[idx] = replace;
idx = content.IndexOfAny(InvalidCharacters, idx+1);
}
return sb.ToString();
}
return content;
}

方法不能按原样编译。dur到InvalidCharacters属性，检查小提琴完整的代码

小开

如果您必须在项目中的许多地方使用该方法，您还可以创建一个扩展方法，并在项目中的任何地方调用它来获取字符串。

 public static class StringExtension
{
public static string RemoveInvalidChars(this string originalString)
{
string finalString=string.Empty;
if (!string.IsNullOrEmpty(originalString))
{
return string.Concat(originalString.Split(Path.GetInvalidFileNameChars()));
}
return finalString;
}
}

你可以这样调用上面的扩展方法:

string illegal = "\"M<>\"\\a/ry/ h**ad:>> a\\/:*?\"<>| li*tt|le|| la\"mb.?";
string afterIllegalChars = illegal.RemoveInvalidChars();