Java URL encoding of query string parameters

Question

Say I have a URL

http://example.com/query?q=

and I have a query entered by the user such as:

random word £500 bank $

I want the result to be a properly encoded URL:

http://example.com/query?q=random%20word%20%A3500%20bank%20%24

What's the best way to achieve this? I tried URLEncoder and creating URI/URL objects but none of them come out quite right.

Answer 1

I would not use URLEncoder. Besides being incorrectly named (URLEncoder has nothing to do with URLs), inefficient (it uses a StringBuffer instead of Builder and does a couple of other things that are slow) Its also way too easy to screw it up.

Instead I would use URIBuilder or Spring's org.springframework.web.util.UriUtils.encodeQueryor Commons Apache HttpClient. The reason being you have to escape the query parameters name (ie BalusC's answer q) differently than the parameter value.

The only downside to the above (that I found out painfully) is that URL's are not a true subset of URI's.

Sample code:

import org.apache.http.client.utils.URIBuilder;

URIBuilder ub = new URIBuilder("http://example.com/query");
ub.addParameter("q", "random word £500 bank \$");
String url = ub.toString();

// Result: http://example.com/query?q=random+word+%C2%A3500+bank+%24

Hope this helps!!

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