how can I clean and sanitize a url submitted by a user for redisplay in java?

Question

I want a user to be able to submit a url, and then display that url to other users as a link.

If I naively redisplay what the user submitted, I leave myself open to urls

Answer 1

You can use apache validator URLValidator

UrlValidator urlValidator = new UrlValidator(schemes);
if (urlValidator.isValid("http://somesite.com")) {
   //valid
}