Session Handling with Firestore tutorial.

session-handling/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+Copyright 2019 Google LLC
+
+ 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
+
+       http://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.
+-->
+<project>
+  <modelVersion>4.0.0</modelVersion>
+  <packaging>war</packaging>
+
+  <groupId>com.example.getstarted</groupId>
+  <artifactId>session-handling</artifactId>
+  <version>1.0-SNAPSHOT</version>
+
+  <parent>
+    <groupId>com.google.cloud.samples</groupId>
+    <artifactId>shared-configuration</artifactId>
+    <version>1.0.11</version>
+  </parent>
+
+  <properties>
+    <gcloud.appId>MY_PROJECT</gcloud.appId>
+
+    <failOnMissingWebXml>false</failOnMissingWebXml>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <maven.compiler.source>11</maven.compiler.source>
+    <maven.compiler.target>11</maven.compiler.target>
+    <maven.compiler.showDeprecation>true</maven.compiler.showDeprecation>
+    <maven.compiler.showWarnings>true</maven.compiler.showWarnings>
+    <maven.compiler.failOnWarning>false</maven.compiler.failOnWarning>
+    <maven.war.filteringDeploymentDescriptors>false</maven.war.filteringDeploymentDescriptors>
+    <jetty.version>9.4.21.v20190926</jetty.version>
+  </properties>
+
+  <dependencies>
+    <!-- https://mvnrepository.com/artifact/com.google.cloud/google-cloud-firestore -->
+    <dependency>
+      <groupId>com.google.cloud</groupId>
+      <artifactId>google-cloud-firestore</artifactId>
+      <version>0.52.0-beta</version>
+    </dependency>
+
+    <dependency>
+      <groupId>javax.servlet</groupId>
+      <artifactId>javax.servlet-api</artifactId>
+      <version>4.0.0</version>
+    </dependency>
+
+    <dependency>
+      <groupId>com.google.guava</groupId>
+      <artifactId>guava</artifactId>
+      <version>23.0</version>
+      <scope>compile</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>io.opencensus</groupId>
+      <artifactId>opencensus-contrib-http-util</artifactId>
+      <version>0.11.1</version>
+    </dependency>
+
+    <!-- Test dependencies -->
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <version>4.12</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.seleniumhq.selenium</groupId>
+      <artifactId>selenium-server</artifactId>
+      <version>3.3.1</version>
+      <scope>test</scope>
+    </dependency>
+    <dependency>
+      <groupId>org.seleniumhq.selenium</groupId>
+      <artifactId>selenium-chrome-driver</artifactId>
+      <version>3.3.1</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <finalName>bookshelf-session-handling</finalName>
+    <!-- Optional - for hot reload of the web application when using an IDE Eclipse / IDEA -->
+    <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes
+    </outputDirectory>
+    <plugins>
+      <plugin>
+        <groupId>org.eclipse.jetty</groupId>
+        <artifactId>jetty-maven-plugin</artifactId>
+        <version>${jetty.version}</version>
+      </plugin>
+      <plugin>
+        <groupId>com.google.cloud.tools</groupId>
+        <artifactId>jib-maven-plugin</artifactId>
+        <version>1.7.0</version>
+        <configuration>
+          <to>
+            <image>gcr.io/${gcloud.appId}/session-handling</image>
+          </to>
+        </configuration>
+      </plugin>
+    </plugins>
+  </build>
+</project>

session-handling/src/main/java/com/example/gettingstarted/actions/HelloWorldServlet.java

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+/* Copyright 2019 Google LLC
+ *
+ * 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
+ *
+ *       http://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 com.example.gettingstarted.actions;
+
+// [START session_handling_servlet]
+
+import java.io.IOException;
+import java.util.Random;
+import java.util.logging.Logger;
+
+import javax.servlet.annotation.WebServlet;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+@WebServlet(
+    name = "helloworld",
+    urlPatterns = {"/"})
+public class HelloWorldServlet extends HttpServlet {
+  private static String[] greetings = {
+    "Hello World", "Hallo Welt", "Ciao Mondo", "Salut le Monde", "Hola Mundo",
+  };
+  private static final Logger logger = Logger.getLogger(HelloWorldServlet.class.getName());
+
+  @Override
+  public void doGet(HttpServletRequest req, HttpServletResponse resp) throws IOException {
+    if (!req.getServletPath().equals("/")) {
+      return;
+    }
+    // Get current values for the session.
+    // If any attribute doesn't exist, add it to the session.
+    Integer views = (Integer) req.getSession().getAttribute("views");
+    if (views == null) {
+      views = 0;
+    }
+    views++;
+    req.getSession().setAttribute("views", views);
+
+    String greeting = (String) req.getSession().getAttribute("greeting");
+    if (greeting == null) {
+      greeting = greetings[new Random().nextInt(greetings.length)];
+      req.getSession().setAttribute("greeting", greeting);
+    }
+
+    logger.info("Writing response " + req.toString());
+    resp.getWriter().write(String.format("%d views for %s", views, greeting));
+  }
+}
+// [END session_handling_servlet]

session-handling/src/main/java/com/example/gettingstarted/util/FirestoreSessionFilter.java

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+/* Copyright 2019 Google LLC
+ *
+ * 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
+ *
+ *       http://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 com.example.gettingstarted.util;
+
+import com.example.gettingstarted.actions.HelloWorldServlet;
+import com.google.cloud.firestore.CollectionReference;
+import com.google.cloud.firestore.DocumentSnapshot;
+import com.google.cloud.firestore.Firestore;
+import com.google.cloud.firestore.FirestoreOptions;
+import com.google.cloud.firestore.QueryDocumentSnapshot;
+import com.google.cloud.firestore.QuerySnapshot;
+import com.google.common.collect.Maps;
+import java.io.IOException;
+import java.math.BigInteger;
+import java.security.SecureRandom;
+import java.text.SimpleDateFormat;
+import java.util.Calendar;
+import java.util.Date;
+import java.util.Enumeration;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import java.util.logging.Logger;
+
+import javax.servlet.Filter;
+import javax.servlet.FilterChain;
+import javax.servlet.FilterConfig;
+import javax.servlet.ServletException;
+import javax.servlet.ServletRequest;
+import javax.servlet.ServletResponse;
+import javax.servlet.annotation.WebFilter;
+import javax.servlet.http.Cookie;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+import javax.servlet.http.HttpSession;
+
+@WebFilter(
+    filterName = "FirestoreSessionFilter ",
+    urlPatterns = {""})
+public class FirestoreSessionFilter implements Filter {
+  private static final SimpleDateFormat dtf = new SimpleDateFormat("yyyyMMddHHmmssSSS");
+  private static final Logger logger = Logger.getLogger(HelloWorldServlet.class.getName());
+  private static Firestore firestore;
+  private static CollectionReference sessions;
+
+  // [START sessions_handling_init]
+  @Override
+  public void init(FilterConfig config) throws ServletException {
+    // Initialize local copy of datastore session variables.
+    firestore = FirestoreOptions.getDefaultInstance().getService();
+    sessions = firestore.collection("sessions");
+
+    try {
+      // Delete all sessions unmodified for over two days.
+      Calendar cal = Calendar.getInstance();
+      cal.setTime(new Date());
+      cal.add(Calendar.HOUR, -48);
+      Date twoDaysAgo = Calendar.getInstance().getTime();
+      QuerySnapshot sessionDocs =
+          sessions.whereLessThan("lastModified", dtf.format(twoDaysAgo)).get().get();
+      for (QueryDocumentSnapshot snapshot : sessionDocs.getDocuments()) {
+        snapshot.getReference().delete();
+      }
+    } catch (InterruptedException | ExecutionException e) {
+      throw new ServletException("Exception initializing FirestoreSessionFilter.", e);
+    }
+  }
+  // [END sessions_handling_init]
+
+  // [START sessions_handling_filter]
+  @Override
+  public void doFilter(ServletRequest servletReq, ServletResponse servletResp, FilterChain chain)
+      throws IOException, ServletException {
+    HttpServletRequest req = (HttpServletRequest) servletReq;
+    HttpServletResponse resp = (HttpServletResponse) servletResp;
+
+    // For this app only call Firestore for requests to base path `/`.
+    if (!req.getServletPath().equals("/")) {
+      chain.doFilter(servletReq, servletResp);
+      return;
+    }
+
+    // Check if the session cookie is there, if not there, make a session cookie using a unique
+    // identifier.
+    String sessionId = getCookieValue(req, "bookshelfSessionId");
+    if (sessionId.equals("")) {
+      String sessionNum = new BigInteger(130, new SecureRandom()).toString(32);
+      Cookie session = new Cookie("bookshelfSessionId", sessionNum);
+      session.setPath("/");
+      resp.addCookie(session);
+    }
+
+    // session variables for request
+    Map<String, Object> firestoreMap = null;
+    try {
+      firestoreMap = loadSessionVariables(req);
+    } catch (ExecutionException | InterruptedException e) {
+      throw new ServletException("Exception loading session variables.", e);
+    }
+
+    for (Map.Entry<String, Object> entry : firestoreMap.entrySet()) {
+      servletReq.setAttribute(entry.getKey(), entry.getValue());
+    }
+
+    // Allow the servlet to process request and response
+    chain.doFilter(servletReq, servletResp);
+
+    // Create session map
+    HttpSession session = req.getSession();
+    Map<String, Object> sessionMap = new HashMap<>();
+    Enumeration<String> attrNames = session.getAttributeNames();
+    while (attrNames.hasMoreElements()) {
+      String attrName = attrNames.nextElement();
+      sessionMap.put(attrName, session.getAttribute(attrName));
+    }
+
+
+    logger.info(
+        "Saving data to " + sessionId + " with views: " + session.getAttribute("views"));
+    firestore.runTransaction((ob) -> sessions.document(sessionId).set(sessionMap));
+  }
+  // [END sessions_handling_filter]
+
+  private String getCookieValue(HttpServletRequest req, String cookieName) {
+    Cookie[] cookies = req.getCookies();
+    if (cookies != null) {
+      for (Cookie cookie : cookies) {
+        if (cookie.getName().equals(cookieName)) {
+          return cookie.getValue();
+        }
+      }
+    }
+    return "";
+  }
+
+  // [START sessions_load_session_variables]
+
+  /**
+   * Take an HttpServletRequest, and copy all of the current session variables over to it
+   *
+   * @param req Request from which to extract session.
+   * @return a map of strings containing all the session variables loaded or an empty map.
+   */
+  private Map<String, Object> loadSessionVariables(HttpServletRequest req)
+      throws ExecutionException, InterruptedException {
+    Map<String, Object> datastoreMap = new HashMap<>();
+    String sessionId = getCookieValue(req, "bookshelfSessionId");
+    if (sessionId.equals("")) {
+      return datastoreMap;
+    }
+
+    return firestore
+        .runTransaction(
+            (ob) -> {
+              DocumentSnapshot session = sessions.document(sessionId).get().get();
+              Map<String, Object> data = session.getData();
+              if (data == null) {
+                data = Maps.newHashMap();
+              }
+              return data;
+            })
+        .get();
+  }
+  // [END sessions_load_session_variables]
+}