web/src/main/java/org/springframework/security/web/authentication/AbstractAuthenticationTargetUrlRequestHandler.java
protected void handle(HttpServletRequest request, HttpServletResponse response,
			Authentication authentication) throws IOException, ServletException {
		String targetUrl = determineTargetUrl(request, response, authentication);

		if (response.isCommitted()) {
			logger.debug("Response has already been committed. Unable to redirect to "
					+ targetUrl);
			return;
		}

		redirectStrategy.sendRedirect(request, response, targetUrl);
	}
protected void handle(HttpServletRequest request, HttpServletResponse response,
			Authentication authentication) throws IOException, ServletException {
		String targetUrl = determineTargetUrl(request, response, authentication);

		if (response.isCommitted()) {
			logger.debug("Response has already been committed. Unable to redirect to "
					+ targetUrl);
			return;
		}

		redirectStrategy.sendRedirect(request, response, targetUrl);
	}
Invokes the configured {@code RedirectStrategy} with the URL returned by the
{@code determineTargetUrl} method.
<p>
The redirect will not be performed if the response has already been committed.