Add a Guestbook example for the standard environment that uses the Cloud

Datastore Java API.

appengine/guestbook-cloud-datastore/README.md

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+# appengine/guestbook-cloud-datastore
+
+An App Engine guestbook using Java, Maven, and the Cloud Datastore API via
+[google-cloud-java](https://github.com/GoogleCloudPlatform/google-cloud-java).
+
+Please ask questions on [StackOverflow](http://stackoverflow.com/questions/tagged/google-app-engine).
+
+## Running Locally
+
+First, pick a project ID. You can create a project in the [Cloud Console] if you'd like, though this
+isn't necessary unless you'd like to deploy the sample.
+
+Second, modify `Persistence.java`: replace `your-project-id-here` with the project ID you picked.
+
+Then start the [Cloud Datastore Emulator](https://cloud.google.com/datastore/docs/tools/datastore-emulator):
+
+    gcloud beta emulators datastore start --project=YOUR_PROJECT_ID_HERE
+
+Finally, in a new shell, [set the Datastore Emulator environmental variables](https://cloud.google.com/datastore/docs/tools/datastore-emulator#setting_environment_variables)
+and run
+
+    mvn clean appengine:devserver
+
+## Deploying
+
+Modify `appengine-web.xml` to reflect your app ID and version, then:
+
+    mvn clean appengine:update

appengine/guestbook-cloud-datastore/pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+
+    <modelVersion>4.0.0</modelVersion>
+    <packaging>war</packaging>
+    <version>1.0-SNAPSHOT</version>
+
+    <groupId>com.example.appengine</groupId>
+    <artifactId>appengine-guestbook-cloud-datastore</artifactId>
+    <properties>
+        <guava.version>19.0</guava.version>
+    </properties>
+    <parent>
+        <groupId>com.google.cloud</groupId>
+        <artifactId>doc-samples</artifactId>
+        <version>1.0.0</version>
+        <relativePath>../..</relativePath>
+    </parent>
+
+    <!-- [START set_versions] -->
+    <prerequisites>
+        <maven>3.3.9</maven>
+    </prerequisites>
+<!-- [END set_versions] -->
+
+    <dependencies>
+        <!-- Compile/runtime dependencies -->
+        <dependency>
+            <groupId>com.google.appengine</groupId>
+            <artifactId>appengine-api-1.0-sdk</artifactId>
+            <version>${appengine.sdk.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>javax.servlet</groupId>
+            <artifactId>servlet-api</artifactId>
+            <version>2.5</version>
+            <scope>provided</scope>
+        </dependency>
+        <dependency>
+            <groupId>jstl</groupId>
+            <artifactId>jstl</artifactId>
+            <version>1.2</version>
+        </dependency>
+
+        <dependency>
+            <groupId>com.google.cloud</groupId>
+            <artifactId>google-cloud</artifactId>
+            <version>0.4.0</version>
+        </dependency>
+
+        <dependency>
+          <groupId>com.google.guava</groupId>
+          <artifactId>guava</artifactId>
+          <version>${guava.version}</version>
+        </dependency>
+
+        <!-- Test Dependencies -->
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.12</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>${appengine.sdk.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <!-- for hot reload of the web application-->
+        <outputDirectory>${project.build.directory}/${project.build.finalName}/WEB-INF/classes</outputDirectory>
+        <plugins>
+            <plugin>
+                <groupId>com.google.appengine</groupId>
+                <artifactId>appengine-maven-plugin</artifactId>
+                <version>${appengine.sdk.version}</version>
+                <configuration>
+                    <enableJarClasses>false</enableJarClasses>
+                    <!-- Comment in the below snippet to bind to all IPs instead of just localhost -->
+                    <!-- address>0.0.0.0</address>
+                    <port>8080</port -->
+                    <!-- Comment in the below snippet to enable local debugging with a remote debugger
+                         like those included with Eclipse or IntelliJ -->
+                    <!-- jvmFlags>
+                      <jvmFlag>-agentlib:jdwp=transport=dt_socket,address=8000,server=y,suspend=n</jvmFlag>
+                    </jvmFlags -->
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+</project>

appengine/guestbook-cloud-datastore/src/main/java/com/example/guestbook/Greeting.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.
+ */
+
+//[START all]
+package com.example.guestbook;
+
+import static com.example.guestbook.Persistence.getDatastore;
+
+import com.google.cloud.datastore.DateTime;
+import com.google.cloud.datastore.Entity;
+import com.google.cloud.datastore.FullEntity;
+import com.google.cloud.datastore.FullEntity.Builder;
+import com.google.cloud.datastore.IncompleteKey;
+import com.google.cloud.datastore.Key;
+import java.util.Date;
+import java.util.Objects;
+
+public class Greeting {
+  private Guestbook book;
+
+  public Key key;
+
+  public String authorEmail;
+  public String authorId;
+  public String content;
+  public Date date;
+
+  public Greeting() {
+    date = new Date();
+  }
+
+  public Greeting(String book, String content) {
+    this();
+    this.book = new Guestbook(book);
+    this.content = content;
+  }
+
+  public Greeting(String book, String content, String id, String email) {
+    this(book, content);
+    authorEmail = email;
+    authorId = id;
+  }
+
+  /**
+   * Load greeting from Datastore entity
+   *
+   * @param entity
+   */
+  public Greeting(Entity entity) {
+    key = entity.hasKey() ? entity.key() : null;
+    authorEmail = entity.contains("authorEmail") ? entity.getString("authorEmail") : null;
+    authorId = entity.contains("authorId") ? entity.getString("authorId") : null;
+    date = entity.contains("date") ? entity.getDateTime("date").toDate() : null;
+    content = entity.contains("content") ? entity.getString("content") : null;
+  }
+
+  public void save() {
+    if (key == null) {
+      key = getDatastore().allocateId(makeIncompleteKey()); // Give this greeting a unique ID
+    }
+
+    Builder<Key> builder = FullEntity.builder(key);
+
+    if (authorEmail != null) {
+      builder.set("authorEmail", authorEmail);
+    }
+
+    if (authorId != null) {
+      builder.set("authorId", authorId);
+    }
+
+    builder.set("content", content);
+    builder.set("date", DateTime.copyFrom(date));
+
+    getDatastore().put(builder.build());
+  }
+
+  private IncompleteKey makeIncompleteKey() {
+    // The book is our ancestor key.
+    return Key.builder(book.getKey(), "Greeting").build();
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (this == o) {
+      return true;
+    }
+    if (o == null || getClass() != o.getClass()) {
+      return false;
+    }
+    Greeting greeting = (Greeting) o;
+    return Objects.equals(key, greeting.key) &&
+        Objects.equals(authorEmail, greeting.authorEmail) &&
+        Objects.equals(authorId, greeting.authorId) &&
+        Objects.equals(content, greeting.content) &&
+        Objects.equals(date, greeting.date);
+  }
+
+  @Override
+  public int hashCode() {
+    return Objects.hash(key, authorEmail, authorId, content, date);
+  }
+}
+//[END all]

appengine/guestbook-cloud-datastore/src/main/java/com/example/guestbook/Guestbook.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.guestbook;
+
+import static com.example.guestbook.Persistence.getDatastore;
+import static com.example.guestbook.Persistence.getKeyFactory;
+import static com.google.cloud.datastore.StructuredQuery.OrderBy.desc;
+import static com.google.cloud.datastore.StructuredQuery.PropertyFilter.hasAncestor;
+
+import com.google.cloud.datastore.Entity;
+import com.google.cloud.datastore.EntityQuery;
+import com.google.cloud.datastore.Key;
+import com.google.cloud.datastore.KeyFactory;
+import com.google.cloud.datastore.Query;
+import com.google.cloud.datastore.QueryResults;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.ImmutableList.Builder;
+import java.util.List;
+
+//[START all]
+public class Guestbook {
+  private static final KeyFactory kf = getKeyFactory(Guestbook.class);
+
+  private final Key key;
+  public final String book;
+
+  public Guestbook(String book) {
+    this.book = book == null ? "default" : book;
+    key = kf.newKey(this.book); // There is a 1:1 mapping between Guestbook names and Guestbook objects
+  }
+
+  public Key getKey() {
+    return key;
+  }
+
+  public List<Greeting> getGreetings() {
+    // This query requires the index defined in index.yaml to work because of the orderBy on date.
+    EntityQuery query = Query.entityQueryBuilder()
+        .kind("Greeting")
+        .filter(hasAncestor(key))
+        .orderBy(desc("date"))
+        .limit(5)
+        .build();
+
+    QueryResults<Entity> results = getDatastore().run(query);
+
+    Builder<Greeting> resultListBuilder = ImmutableList.builder();
+    while (results.hasNext()) {
+      resultListBuilder.add(new Greeting(results.next()));
+    }
+
+    return resultListBuilder.build();
+  }
+}
+//[END all]

appengine/guestbook-cloud-datastore/src/main/java/com/example/guestbook/Persistence.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.guestbook;
+
+import com.google.cloud.datastore.Datastore;
+import com.google.cloud.datastore.DatastoreOptions;
+import com.google.cloud.datastore.KeyFactory;
+
+import java.util.concurrent.atomic.AtomicReference;
+
+//[START all]
+public class Persistence {
+  private static AtomicReference<Datastore> datastore = new AtomicReference<>();
+
+  public static Datastore getDatastore() {
+    if (datastore.get() == null) {
+      datastore.set(DatastoreOptions.builder().projectId("your-project-id-here").build().service());
+    }
+
+    return datastore.get();
+  }
+
+  public static KeyFactory getKeyFactory(Class<?> c) {
+    return getDatastore().newKeyFactory().kind(c.getSimpleName());
+  }
+
+  public static void setDatastore(Datastore datastore) {
+    Persistence.datastore.set(datastore);
+  }
+}
+//[END all]