JSTL < c:url >

<c:url value='/abc' /> = context root name + "/abc"

In jsp
Context root name = ${pageContext.request.contextPath} (e.g. myApp)

Note c:url doesn't do URL encoding -- it doesn't convert 'a b' to 'a%20b'

Neither HttpServletResponse.encodeURL(Strin url) nor HttpServletResponse.encodeRedirectURL(String url) encodes URL

URLEncoder.encode(String url) does the job

http://www.cnblogs.com/season-huang/p/3439277.html
https://bluxte.net/musings/2006/03/29/servletpath-and-pathinfo-servlet-api-weirdness/