How to uri encode a string in jsp?

Question

if I have a string "output" that equals a url:

${output} = "/testing/method/thing.do?foo=testing&bar=foo"

in the jsp, how would I convert that string into:

%2Ftesting%2Fmethod%2Fthing.do%3Ffoo%3Dtesting%26bar%3Dfoo

using

<c:out value="${output}"/>

? I need to URLEncoder.encode(url) in the c:out somehow.

Answer 1

It's not directly possible with standard JSTL tags/functions. Here's a hack with help of <c:url>:

<c:url var="url" value=""><c:param name="output" value="${output}" /></c:url>
<c:set var="url" value="${fn:substringAfter(url, '=')}" />
<p>URL-encoded component: ${url}</p>

If you want to do it more cleanly, create an EL function. At the bottom of this answer you can find a basic kickoff example. You'd like to end up as:

<p>URL-encoded component: ${my:urlEncode(output, 'UTF-8')}</p>

with

public static String urlEncode(String value, String charset) throws UnsupportedEncodingException {
    return URLEncoder.encode(value, charset);
}