web/src/main/java/org/springframework/security/web/authentication/LoginUrlAuthenticationEntryPoint.java
public void commence(HttpServletRequest request, HttpServletResponse response,
			AuthenticationException authException) throws IOException, ServletException {

		String redirectUrl = null;

		if (useForward) {

			if (forceHttps && "http".equals(request.getScheme())) {
				// First redirect the current request to HTTPS.
				// When that request is received, the forward to the login page will be
				// used.
				redirectUrl = buildHttpsRedirectUrlForRequest(request);
			}

			if (redirectUrl == null) {
				String loginForm = determineUrlToUseForThisRequest(request, response,
						authException);

				if (logger.isDebugEnabled()) {
					logger.debug("Server side forward to: " + loginForm);
				}

				RequestDispatcher dispatcher = request.getRequestDispatcher(loginForm);

				dispatcher.forward(request, response);

				return;
			}
		}
		else {
			// redirect to login page. Use https if forceHttps true

			redirectUrl = buildRedirectUrlToLoginPage(request, response, authException);

		}

		redirectStrategy.sendRedirect(request, response, redirectUrl);
	}
public void commence(HttpServletRequest request, HttpServletResponse response,
			AuthenticationException authException) throws IOException, ServletException {

		String redirectUrl = null;

		if (useForward) {

			if (forceHttps && "http".equals(request.getScheme())) {
				// First redirect the current request to HTTPS.
				// When that request is received, the forward to the login page will be
				// used.
				redirectUrl = buildHttpsRedirectUrlForRequest(request);
			}

			if (redirectUrl == null) {
				String loginForm = determineUrlToUseForThisRequest(request, response,
						authException);

				if (logger.isDebugEnabled()) {
					logger.debug("Server side forward to: " + loginForm);
				}

				RequestDispatcher dispatcher = request.getRequestDispatcher(loginForm);

				dispatcher.forward(request, response);

				return;
			}
		}
		else {
			// redirect to login page. Use https if forceHttps true

			redirectUrl = buildRedirectUrlToLoginPage(request, response, authException);

		}

		redirectStrategy.sendRedirect(request, response, redirectUrl);
	}
Performs the redirect (or forward) to the login form URL.