web/src/main/java/org/springframework/security/web/DefaultRedirectStrategy.java
public void sendRedirect(HttpServletRequest request, HttpServletResponse response,
			String url) throws IOException {
		String redirectUrl = calculateRedirectUrl(request.getContextPath(), url);
		redirectUrl = response.encodeRedirectURL(redirectUrl);

		if (logger.isDebugEnabled()) {
			logger.debug("Redirecting to '" + redirectUrl + "'");
		}

		response.sendRedirect(redirectUrl);
	}
public void sendRedirect(HttpServletRequest request, HttpServletResponse response,
			String url) throws IOException {
		String redirectUrl = calculateRedirectUrl(request.getContextPath(), url);
		redirectUrl = response.encodeRedirectURL(redirectUrl);

		if (logger.isDebugEnabled()) {
			logger.debug("Redirecting to '" + redirectUrl + "'");
		}

		response.sendRedirect(redirectUrl);
	}
Redirects the response to the supplied URL.
<p>
If <tt>contextRelative</tt> is set, the redirect value will be the value after the
request context path. Note that this will result in the loss of protocol
information (HTTP or HTTPS), so will cause problems if a redirect is being
performed to change to HTTPS, for example.