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How to get the base url from the jsp request object? http://localhost:8080/SOMETHING/index.jsp, but I want the part till index.jsp, how is it possible in jsp?

BalusC
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Maverick
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  • there are many ways. Why exactly do you need it? – Bozho Jun 07 '11 at 20:20
  • I have some requirement for which I need the url of the web container. So, I need a path till http://localhost:8080/my_web_container. – Maverick Jun 07 '11 at 20:22
  • this is now "web container", but "context". And do you need it absolute, or relative (to the host) – Bozho Jun 07 '11 at 20:24

6 Answers6

56

So, you want the base URL? You can get it in a servlet as follows:

String url = request.getRequestURL().toString();
String baseURL = url.substring(0, url.length() - request.getRequestURI().length()) + request.getContextPath() + "/";
// ...

Or in a JSP, as <base>, with little help of JSTL:

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<%@taglib prefix="fn" uri="http://java.sun.com/jsp/jstl/functions" %>
<c:set var="req" value="${pageContext.request}" />
<c:set var="url">${req.requestURL}</c:set>
<c:set var="uri" value="${req.requestURI}" />
...
<head>
    <base href="${fn:substring(url, 0, fn:length(url) - fn:length(uri))}${req.contextPath}/" />
</head>

Note that this does not include the port number when it's already the default port number, such as 80. The java.net.URL doesn't take this into account.

See also:

Community
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BalusC
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18

JSP variant of Bozho's answer:

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<c:set var="req" value="${pageContext.request}" />
<c:set var="baseURL" value="${req.scheme}://${req.serverName}:${req.serverPort}${req.contextPath}" />
hfmanson
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14
new URL(request.getScheme(), 
        request.getServerName(), 
        request.getServerPort(), 
        request.getContextPath());
Bozho
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    what you you mean "till"? It will generate what you want, I think. Try it. – Bozho Jun 07 '11 at 20:24
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    Note that this will even for default port numbers (http+80 and https+443) still include the port number in the final result. This is not always desireable, for sure not if the URL is to be used in some redirect URL or as `` URL. – BalusC Jun 07 '11 at 20:34
0

There is one major flaw in @BalusC accepted answer though. Substring should start from 0 and not 1. Instead of 

<base href="${fn:replace(req.requestURL, fn:substring(uri, 1, fn:length(uri)), req.contextPath)}" />

it should be

<base href="${fn:replace(req.requestURL, fn:substring(uri, 0, fn:length(uri)), req.contextPath)}" />

With 1 you get double forward slash: http://localhost:8080//appcontext/ With 0 you get, http://localhost:21080/appcontext/

In my application, request.getSession(false) always returned null when it was ending in double slash!!!

Boss Man
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-3

just use isSecure()

{<%=request.isSecure()?"https":"http:"%>}

prakie
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-3

Instead of doing all of that, just do this:

request.getServerName().toString()
Quinton Pike
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