#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/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;
+