Question

In my blog app, a user can enter any text as a title for their entry and then I generate a URL based on the text.

I validate their title to make sure it only contains letters and numbers.

If they enter something like

Lorem 3 ipsum dolor sit amet

how could I generate the more SEO friendly version of this text:

Lorem-3-ipsum-dolor-sit-amet

Answer 1

It’s in practice really not as simple as replacing spaces by hypens. You would often also like to make it all lowercase and normalize/replace diacritics, like á, ö, è and so on which are invalid URL characters. The only valid characters are listed as "Unreserved characters" in the 2nd table of this Wikipedia page.

Here’s how such a function can look like:

public static String prettyURL(String string) {
    return Normalizer.normalize(string.toLowerCase(), Form.NFD)
        .replaceAll("\\p{InCombiningDiacriticalMarks}+", "")
        .replaceAll("[^\\p{Alnum}]+", "-");
}

It does basically the following:

• lowercase the string
• remove combining diacritical marks (after the Normalizer has "extracted" them from the actual chars)
• replace non-alphanumeric characters by hyphens

See also:

• JSP 2.0 SEO friendly links encoding