我们是这样做的。注意，可能有比你第一眼意识到的更多的边缘条件。

这是第二个版本，展开后的性能提高了5倍(是的，我对它进行了基准测试)。我认为我应该优化它，因为这个函数可以在每页被调用数百次。

/// <summary>
/// Produces optional, URL-friendly version of a title, "like-this-one". 
/// hand-tuned for speed, reflects performance refactoring contributed
/// by John Gietzen (user otac0n) 
/// </summary>
public static string URLFriendly(string title)
{
    if (title == null) return "";

    const int maxlen = 80;
    int len = title.Length;
    bool prevdash = false;
    var sb = new StringBuilder(len);
    char c;

    for (int i = 0; i < len; i++)
    {
        c = title[i];
        if ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9'))
        {
            sb.Append(c);
            prevdash = false;
        }
        else if (c >= 'A' && c <= 'Z')
        {
            // tricky way to convert to lowercase
            sb.Append((char)(c | 32));
            prevdash = false;
        }
        else if (c == ' ' || c == ',' || c == '.' || c == '/' || 
            c == '\\' || c == '-' || c == '_' || c == '=')
        {
            if (!prevdash && sb.Length > 0)
            {
                sb.Append('-');
                prevdash = true;
            }
        }
        else if ((int)c >= 128)
        {
            int prevlen = sb.Length;
            sb.Append(RemapInternationalCharToAscii(c));
            if (prevlen != sb.Length) prevdash = false;
        }
        if (i == maxlen) break;
    }

    if (prevdash)
        return sb.ToString().Substring(0, sb.Length - 1);
    else
        return sb.ToString();
}

要查看被替换的代码的前一个版本(但在功能上与之相当，而且快了5倍)，请查看这篇文章的修订历史(单击日期链接)。

另外，RemapInternationalCharToAscii方法的源代码可以在这里找到。

Brian的Ruby代码:

title.downcase.strip.gsub(/\ /, '-').gsub(/[^\w\-]/, '')

Downcase将字符串转换为小写，strip删除开头和结尾的空格，第一个gsub调用全局地用破折号替换空格，第二个调用删除所有不是字母或破折号的内容。

下面是我的(稍慢，但写起来很有趣)Jeff的代码版本:

public static string URLFriendly(string title)
{
    char? prevRead = null,
        prevWritten = null;

    var seq = 
        from c in title
        let norm = RemapInternationalCharToAscii(char.ToLowerInvariant(c).ToString())[0]
        let keep = char.IsLetterOrDigit(norm)
        where prevRead.HasValue || keep
        let replaced = keep ? norm
            :  prevWritten != '-' ? '-'
            :  (char?)null
        where replaced != null
        let s = replaced + (prevRead == null ? ""
            : norm == '#' && "cf".Contains(prevRead.Value) ? "sharp"
            : norm == '+' ? "plus"
            : "")
        let _ = prevRead = norm
        from written in s
        let __ = prevWritten = written
        select written;

    const int maxlen = 80;  
    return string.Concat(seq.Take(maxlen)).TrimEnd('-');
}

public static string RemapInternationalCharToAscii(string text)
{
    var seq = text.Normalize(NormalizationForm.FormD)
        .Where(c => CharUnicodeInfo.GetUnicodeCategory(c) != UnicodeCategory.NonSpacingMark);

    return string.Concat(seq).Normalize(NormalizationForm.FormC);
}

我的测试字符串:

“我喜欢c#， f#， c++，还有……焦糖布丁! !他们看到我在编程……他们hatin”……想抓住我的下流行为……”

假设你的模型类有一个title属性，你可以简单地覆盖模型中的to_param方法，就像这样:

def to_param
  title.downcase.gsub(/ /, '-')
end

Railscast的这集有所有的细节。你也可以使用这个来确保标题只包含有效字符:

validates_format_of :title, :with => /^[a-z0-9-]+$/,
                    :message => 'can only contain letters, numbers and hyphens'

我不太了解Ruby或Rails，但在Perl中，这是我要做的:

my $title = "How do you change a title to be part of the url like Stackoverflow?";

my $url = lc $title;   # Change to lower case and copy to URL.
$url =~ s/^\s+//g;     # Remove leading spaces.
$url =~ s/\s+$//g;     # Remove trailing spaces.
$url =~ s/\s+/\-/g;    # Change one or more spaces to single hyphen.
$url =~ s/[^\w\-]//g;  # Remove any non-word characters.

print "$title\n$url\n";

我刚做了一个快速测试，似乎有用。希望这在Ruby中比较容易翻译。

T-SQL实现，改编自dbo。UrlEncode:

CREATE FUNCTION dbo.Slug(@string varchar(1024))
RETURNS varchar(3072)
AS
BEGIN
    DECLARE @count int, @c char(1), @i int, @slug varchar(3072)

    SET @string = replace(lower(ltrim(rtrim(@string))),' ','-')

    SET @count = Len(@string)
    SET @i = 1
    SET @slug = ''

    WHILE (@i <= @count)
    BEGIN
        SET @c = substring(@string, @i, 1)

        IF @c LIKE '[a-z0-9--]'
            SET @slug = @slug + @c

        SET @i = @i +1
    END

    RETURN @slug
END