#54 - Added a project for MongoDB examples using Java 8 features.

This initial version of the example projects demonstrates the usage and mapping behavior of Java 8 Streams in repositories. The test cases oppose a plain List based query method with one that uses a Stream and shows how the former pulls all data into memory first and the iteration is done over the pre-populated list. The execution of the Stream based method in contrast shows that the individual elements are read and converted while iterating the stream.

mongodb/java8/README.md

@@ -0,0 +1,21 @@
+# Spring Data MongoDB - Java 8 examples
+
+This project contains samples of Java 8 specific features of Spring Data (MongoDB).
+
+## Support for JDK 8's `Stream` for repository methods
+
+Repository methods can use a Java 8 `Stream` as a return type which will cause the reading of the results and the to-object-conversion of the `DBObject` to happen while iterating over the stream.
+
+```java
+public interface PersonRepository extends CrudRepository<Person, String> {
+
+  @Override
+  List<Person> findAll();
+
+  //Custom Query method returning a Java 8 Stream
+  @Query("{}")
+  Stream<Person> findAllByCustomQueryWithStream();
+}
+```
+
+The test cases in `PersonRepositoryIntegrationTest` oppose a plain `List` based query method with one that uses a `Stream` and shows how the former pulls all data into memory first and the iteration is done over the pre-populated list. The execution of the `Stream`-based method in contrast shows that the individual elements are read and converted while iterating the stream.

mongodb/java8/pom.xml

@@ -0,0 +1,33 @@
+<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>
+
+	<parent>
+		<groupId>org.springframework.data.examples</groupId>
+		<artifactId>spring-data-mongodb-examples</artifactId>
+		<version>1.0.0.BUILD-SNAPSHOT</version>
+	</parent>
+
+	<artifactId>spring-data-mongodb-java8</artifactId>
+	<name>Spring Data MongoDB - Java 8 specific features</name>
+
+	<properties>
+		<spring-data-releasetrain.version>Fowler-BUILD-SNAPSHOT</spring-data-releasetrain.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>${project.groupId}</groupId>
+			<artifactId>spring-data-mongodb-utils</artifactId>
+			<version>${project.version}</version>
+			<scope>test</scope>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework.data</groupId>
+			<artifactId>spring-data-mongodb</artifactId>
+		</dependency>
+
+	</dependencies>
+
+</project>

mongodb/java8/src/main/java/example/springdata/mongodb/people/ApplicationConfiguration.java

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2015 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
+ *
+ *      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 example.springdata.mongodb.people;
+
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.data.mongodb.core.mapping.event.LoggingEventListener;
+
+/**
+ * Simple configuration that registers a {@link LoggingEventListener} to demonstrate mapping behaviour when Java 8
+ * Streams are used.
+ * 
+ * @author Thomas Darimont
+ */
+@SpringBootApplication
+class ApplicationConfiguration {
+
+	public @Bean LoggingEventListener mongoEventListener() {
+		return new LoggingEventListener();
+	}
+}

mongodb/java8/src/main/java/example/springdata/mongodb/people/Person.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2015 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
+ *
+ *      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 example.springdata.mongodb.people;
+
+import lombok.Data;
+import lombok.RequiredArgsConstructor;
+
+import org.springframework.data.annotation.Id;
+
+/**
+ * An entity to represent a Person.
+ * 
+ * @author Thomas Darimont
+ */
+@Data
+@RequiredArgsConstructor
+public class Person {
+
+	private @Id String id;
+	private final String firstname;
+	private final String lastname;
+}

mongodb/java8/src/main/java/example/springdata/mongodb/people/PersonRepository.java

@@ -0,0 +1,35 @@
+/*
+ * Copyright 2015 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
+ *
+ *      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 example.springdata.mongodb.people;
+
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.springframework.data.mongodb.repository.Query;
+import org.springframework.data.repository.CrudRepository;
+
+/**
+ * Repository interface to manage {@link Person} instances.
+ * 
+ * @author Thomas Darimont
+ */
+public interface PersonRepository extends CrudRepository<Person, String> {
+
+	List<Person> findAll();
+
+	@Query("{}")
+	Stream<Person> findAllByCustomQueryWithStream();
+}

mongodb/java8/src/test/java/example/springdata/mongodb/people/PersonRepositoryIntegrationTest.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2015 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
+ *
+ *      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 example.springdata.mongodb.people;
+
+import org.junit.Before;
+import org.junit.ClassRule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.data.mongodb.core.MongoOperations;
+import org.springframework.data.mongodb.core.mapping.event.LoggingEventListener;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+
+import example.springdata.mongodb.util.RequiresMongoDB;
+
+/**
+ * Integration test for {@link PersonRepository}.
+ * 
+ * @author Thomas Darimont
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = ApplicationConfiguration.class)
+public class PersonRepositoryIntegrationTest {
+
+	@ClassRule public static RequiresMongoDB mongodbAvailable = RequiresMongoDB.anyVersion();
+
+	@Autowired PersonRepository repository;
+	@Autowired MongoOperations operations;
+
+	Person dave, oliver, carter;
+
+	@Before
+	public void setUp() {
+
+		repository.deleteAll();
+
+		dave = repository.save(new Person("Dave", "Matthews"));
+		oliver = repository.save(new Person("Oliver August", "Matthews"));
+		carter = repository.save(new Person("Carter", "Beauford"));
+	}
+
+	/**
+	 * Note that the all object conversions are preformed before the results are printed to the console.
+	 */
+	@Test
+	public void shouldPerformConversionBeforeResultProcessing() {
+		repository.findAll().forEach(System.out::println);
+	}
+
+	/**
+	 * Note that the object conversions are preformed during stream processing as one can see from the
+	 * {@link LoggingEventListener} output that is printed to the console.
+	 */
+	@Test
+	public void shouldPerformConversionDuringJava8StreamProcessing() {
+		repository.findAllByCustomQueryWithStream().forEach(System.out::println);
+	}
+}

mongodb/java8/src/test/java/example/springdata/mongodb/people/package-info.java

@@ -0,0 +1,5 @@
+/**
+ * Package showing usage of Spring Data MongoDB Repositories with Java 8.
+ */
+package example.springdata.mongodb.people;
+

mongodb/pom.xml

@@ -14,12 +14,13 @@
 	<name>Spring Data MongoDB - Examples</name>
 	<description>Sample projects for Spring Data MongoDB</description>
 	<url>http://projects.spring.io/spring-data-mongodb</url>
-	<inceptionYear>2011-2014</inceptionYear>
+	<inceptionYear>2011-2015</inceptionYear>
 
 	<modules>
 	    <module>aggregation</module>
 		<module>example</module>
 		<module>text-search</module>
+		<module>java8</module>
 		<module>util</module>
 	</modules>