Add RequestedUrlRedirectInvalidSessionStrategy implemention of InvalidSessionStrategy

Performs a redirect to the original request URL when an invalid requested session is detected.

In effect, when a user's session times out, the user is redirected to URL they originally requested instead of some fixed URL.

web/src/main/java/org/springframework/security/web/session/RequestedUrlRedirectInvalidSessionStrategy.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2002-2016 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.web.session;
+
+import java.io.IOException;
+import java.util.Optional;
+
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.security.web.DefaultRedirectStrategy;
+import org.springframework.security.web.RedirectStrategy;
+import org.springframework.web.util.UrlPathHelper;
+
+/**
+ * Performs a redirect to the original request URL when an invalid requested session is
+ * detected by the {@code SessionManagementFilter}.
+ *
+ * @author Craig Andrews
+ */
+public final class RequestedUrlRedirectInvalidSessionStrategy implements InvalidSessionStrategy {
+
+	private final Log logger = LogFactory.getLog(getClass());
+
+	private final RedirectStrategy redirectStrategy = new DefaultRedirectStrategy();
+
+	private boolean createNewSession = true;
+
+	private final UrlPathHelper urlPathHelper = new UrlPathHelper();
+
+	@Override
+	public void onInvalidSessionDetected(HttpServletRequest request, HttpServletResponse response) throws IOException {
+		String destinationUrl = this.urlPathHelper.getOriginatingRequestUri(request)
+				+ Optional.ofNullable(this.urlPathHelper.getOriginatingQueryString(request)).filter((s) -> !s.isEmpty())
+						.map((s) -> "?" + s).orElse("");
+		this.logger.debug("Starting new session (if required) and redirecting to '" + destinationUrl + "'");
+		if (this.createNewSession) {
+			request.getSession();
+		}
+		this.redirectStrategy.sendRedirect(request, response, destinationUrl);
+	}
+
+	/**
+	 * Determines whether a new session should be created before redirecting (to avoid
+	 * possible looping issues where the same session ID is sent with the redirected
+	 * request). Alternatively, ensure that the configured URL does not pass through the
+	 * {@code SessionManagementFilter}.
+	 * @param createNewSession defaults to {@code true}.
+	 */
+	public void setCreateNewSession(boolean createNewSession) {
+		this.createNewSession = createNewSession;
+	}
+
+}