How to URL encode a URL in JSP / JSTL?

The accepted answer is missing some JSP code to be valid, it should be:

<c:url value="/yourClient" var="url">
  <c:param name="yourParamName" value="http://google.com/index.html" />
</c:url>

<a href="<c:out value='${url}'/>">Link to your client</a>

As a comment pointed out, another option is to use JavaScripts encodeURIComponent method.

Using UrlEncoder.encode() is the answer. But the point is that this method doesn't percentage encode. Use:

java.net.UrlEncoder.encode(stringOfURL,"UTF-8").replace("+","%20")

Since you are using JSP, I would stick to JSTL and not use scriptlets. You could use the JSTL tag <c:url /> in combination with <c:param />:

<c:url value="/yourClient" var="url">
  <c:param name="yourParamName" value="http://google.com/index.html" />
</c:url>

<a href="${url}">Link to your client</a>

This will result in:

<a href="/yourClient?yourParamName=http%3a%2f%2fgoogle.com%2findex.html">Link to your client</a>