AppEngine Channel Example with Tic Tac Toe + Java

appengine/channel/pom.xml

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+<!--
+ Copyright 2015 Google Inc. All Rights Reserved.
+
+ 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>
+    <version>1.0-SNAPSHOT</version>
+    <groupId>com.example.appengine</groupId>
+    <artifactId>appengine-channel</artifactId>
+    <parent>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>doc-samples</artifactId>
+        <version>1.0.0</version>
+        <relativePath>../..</relativePath>
+    </parent>
+    <properties>
+        <objectify.version>5.1.5</objectify.version>
+    </properties>
+    <!-- [START set_versions] -->
+    <prerequisites>
+        <maven>3.3.9</maven>
+    </prerequisites>
+    <!-- [END set_versions] -->
+    <dependencies>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-1.0-sdk</artifactId>
+            <version>${appengine.sdk.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>servlet-api</artifactId>
+            <version>2.5</version>
+            <type>jar</type>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.json</groupId>
+            <artifactId>json</artifactId>
+            <version>20160212</version>
+        </dependency>
+        <dependency>
+            <groupId>com.googlecode.objectify</groupId>
+            <artifactId>objectify</artifactId>
+            <version>${objectify.version}</version>
+        </dependency>
+
+        <!-- Test Dependencies -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.10</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-all</artifactId>
+            <version>1.10.19</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-testing</artifactId>
+            <version>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-stubs</artifactId>
+            <version>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-tools-sdk</artifactId>
+            <version>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>com.google.truth</groupId>
+            <artifactId>truth</artifactId>
+            <version>0.28</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+    <build>
+        <!-- for hot reload of the web application -->
+        <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes
+        </outputDirectory>
+        <plugins>
+            <!-- Parent POM defines ${appengine.sdk.version} (updates frequently). -->
+            <plugin>
+                <groupId>com.google.appengine</groupId>
+                <artifactId>appengine-maven-plugin</artifactId>
+                <version>${appengine.sdk.version}</version>
+            </plugin>
+        </plugins>
+    </build>
+</project>

appengine/channel/src/main/java/com/example/appengine/channel/Game.java

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+/*
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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.appengine.channel;
+
+import com.google.appengine.api.channel.ChannelMessage;
+import com.google.appengine.api.channel.ChannelService;
+import com.google.appengine.api.channel.ChannelServiceFactory;
+import com.googlecode.objectify.annotation.Entity;
+import com.googlecode.objectify.annotation.Id;
+import org.json.JSONObject;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+import java.util.regex.Pattern;
+
+@Entity
+public class Game {
+  static final Pattern[] XWins =
+      {Pattern.compile("XXX......"), Pattern.compile("...XXX..."), Pattern.compile("......XXX"),
+          Pattern.compile("X..X..X.."), Pattern.compile(".X..X..X."),
+          Pattern.compile("..X..X..X"), Pattern.compile("X...X...X"),
+          Pattern.compile("..X.X.X..")};
+  static final Pattern[] OWins =
+      {Pattern.compile("OOO......"), Pattern.compile("...OOO..."), Pattern.compile("......OOO"),
+          Pattern.compile("O..O..O.."), Pattern.compile(".O..O..O."),
+          Pattern.compile("..O..O..O"), Pattern.compile("O...O...O"),
+          Pattern.compile("..O.O.O..")};
+
+  @Id
+  public String id;
+  private String userX;
+  private String userO;
+  private String board;
+  private Boolean moveX;
+  private String winner;
+  private String winningBoard;
+
+  Game() {
+  }
+
+  Game(String userX, String userO, String board, boolean moveX) {
+    this.id = UUID.randomUUID().toString();
+    this.userX = userX;
+    this.userO = userO;
+    this.board = board;
+    this.moveX = moveX;
+  }
+
+  public String getId() {
+    return id;
+  }
+
+  public void setId(String id) {
+    this.id = id;
+  }
+
+  public String getUserX() {
+    return userX;
+  }
+
+  public String getUserO() {
+    return userO;
+  }
+
+  public void setUserO(String userO) {
+    this.userO = userO;
+  }
+
+  public String getBoard() {
+    return board;
+  }
+
+  public void setBoard(String board) {
+    this.board = board;
+  }
+
+  public boolean getMoveX() {
+    return moveX;
+  }
+
+  public void setMoveX(boolean moveX) {
+    this.moveX = moveX;
+  }
+
+  public String getMessageString() {
+    Map<String, String> state = new HashMap<String, String>();
+    state.put("userX", userX);
+    if (userO == null) {
+      state.put("userO", "");
+    } else {
+      state.put("userO", userO);
+    }
+    state.put("board", board);
+    state.put("moveX", moveX.toString());
+    state.put("winner", winner);
+    if (winner != null && winner != "") {
+      state.put("winningBoard", winningBoard);
+    }
+    JSONObject message = new JSONObject(state);
+    return message.toString();
+  }
+
+  public String getChannelKey(String user) {
+    return user + id;
+  }
+
+  private void sendUpdateToUser(String user) {
+    if (user != null) {
+      ChannelService channelService = ChannelServiceFactory.getChannelService();
+      String channelKey = getChannelKey(user);
+      channelService.sendMessage(new ChannelMessage(channelKey, getMessageString()));
+    }
+  }
+
+  public void sendUpdateToClients() {
+    sendUpdateToUser(userX);
+    sendUpdateToUser(userO);
+  }
+
+  public void checkWin() {
+    final Pattern[] wins;
+    if (moveX) {
+      wins = XWins;
+    } else {
+      wins = OWins;
+    }
+
+    for (Pattern winPattern : wins) {
+      if (winPattern.matcher(board).matches()) {
+        if (moveX) {
+          winner = userX;
+        } else {
+          winner = userO;
+        }
+        winningBoard = winPattern.toString();
+      }
+    }
+  }
+
+  public boolean makeMove(int position, String user) {
+    String currentMovePlayer;
+    char value;
+    if (getMoveX()) {
+      value = 'X';
+      currentMovePlayer = getUserX();
+    } else {
+      value = 'O';
+      currentMovePlayer = getUserO();
+    }
+
+    if (currentMovePlayer.equals(user)) {
+      char[] boardBytes = getBoard().toCharArray();
+      boardBytes[position] = value;
+      setBoard(new String(boardBytes));
+      checkWin();
+      setMoveX(!getMoveX());
+      sendUpdateToClients();
+      return true;
+    }
+
+    return false;
+  }
+}

appengine/channel/src/main/java/com/example/appengine/channel/GetTokenServlet.java

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+/*
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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.appengine.channel;
+
+import com.google.appengine.api.channel.ChannelService;
+import com.google.appengine.api.channel.ChannelServiceFactory;
+import com.google.appengine.api.users.UserService;
+import com.google.appengine.api.users.UserServiceFactory;
+import com.googlecode.objectify.Objectify;
+import com.googlecode.objectify.ObjectifyService;
+
+import java.io.IOException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+public class GetTokenServlet extends HttpServlet {
+  @Override
+  public void doPost(HttpServletRequest req, HttpServletResponse resp)
+      throws IOException {
+    UserService userService = UserServiceFactory.getUserService();
+    String gameId = req.getParameter("gamekey");
+    Objectify ofy = ObjectifyService.ofy();
+    Game game = ofy.load().type(Game.class).id(gameId).safe();
+
+    String currentUserId = userService.getCurrentUser().getUserId();
+    if (currentUserId.equals(game.getUserX()) || currentUserId.equals(game.getUserO())) {
+      String channelKey = game.getChannelKey(currentUserId);
+      ChannelService channelService = ChannelServiceFactory.getChannelService();
+      resp.setContentType("text/plain");
+      resp.getWriter().println(channelService.createChannel(channelKey));
+      return;
+    }
+    resp.setStatus(HttpServletResponse.SC_FORBIDDEN);
+  }
+}

appengine/channel/src/main/java/com/example/appengine/channel/MoveServlet.java

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+/*
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ *
+ * 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.appengine.channel;
+
+import com.google.appengine.api.users.UserService;
+import com.google.appengine.api.users.UserServiceFactory;
+import com.googlecode.objectify.Objectify;
+import com.googlecode.objectify.ObjectifyService;
+
+import java.io.IOException;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+public class MoveServlet extends HttpServlet {
+  @Override
+  public void doPost(HttpServletRequest req, HttpServletResponse resp)
+      throws IOException {
+    UserService userService = UserServiceFactory.getUserService();
+    String gameId = req.getParameter("gamekey");
+    int piece = new Integer(req.getParameter("i"));
+    Objectify ofy = ObjectifyService.ofy();
+    Game game = ofy.load().type(Game.class).id(gameId).safe();
+
+    String currentUserId = userService.getCurrentUser().getUserId();
+    if (!game.makeMove(piece, currentUserId)) {
+      resp.setStatus(HttpServletResponse.SC_FORBIDDEN);
+    } else {
+      ofy.save().entity(game).now();
+    }
+  }
+}