Added showcase for JDK 8's Optional support on repository methods.

Abbreviated JPA sample module folder names. Renamed the Java 8 auditing sample module to Java 8 module as it not only contains samples for auditing anymore.

jpa/java8/src/main/java/example/springdata/jpa/java8/AbstractEntity.java

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+/*
+ * Copyright 2013-2014 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.jpa.java8;
+
+import java.time.ZonedDateTime;
+
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.MappedSuperclass;
+
+import org.springframework.data.annotation.CreatedDate;
+import org.springframework.data.annotation.LastModifiedDate;
+
+/**
+ * @author Oliver Gierke
+ */
+@MappedSuperclass
+public class AbstractEntity {
+
+	@Id @GeneratedValue Long id;
+
+	@CreatedDate//
+	// @Type(type = "org.jadira.usertype.dateandtime.threetenbp.PersistentZonedDateTime")//
+	ZonedDateTime createdDate;
+
+	@LastModifiedDate//
+	// @Type(type = "org.jadira.usertype.dateandtime.threetenbp.PersistentZonedDateTime")//
+	ZonedDateTime modifiedDate;
+}

jpa/java8/src/main/java/example/springdata/jpa/java8/AuditingConfiguration.java

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+/*
+ * Copyright 2014 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.jpa.java8;
+
+import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
+
+@Configuration
+@EnableAutoConfiguration
+@EnableJpaAuditing
+class AuditingConfiguration {
+
+}

jpa/java8/src/main/java/example/springdata/jpa/java8/Customer.java

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+/*
+ * Copyright 2013-2014 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.jpa.java8;
+
+import javax.persistence.Entity;
+
+/**
+ * @author Oliver Gierke
+ */
+@Entity
+public class Customer extends AbstractEntity {
+
+	String firstname, lastname;
+
+	public Customer(String firstname, String lastname) {
+
+		this.firstname = firstname;
+		this.lastname = lastname;
+	}
+}

jpa/java8/src/main/java/example/springdata/jpa/java8/CustomerRepository.java

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+/*
+ * Copyright 2013-2014 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.jpa.java8;
+
+import java.util.Optional;
+
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.Repository;
+
+/**
+ * Repository to manage {@link Customer} instances.
+ * 
+ * @author Oliver Gierke
+ */
+public interface CustomerRepository extends Repository<Customer, Long> {
+
+	/**
+	 * Special customization of {@link CrudRepository#findOne(java.io.Serializable)} to return a JDK 8 {@link Optional}.
+	 * 
+	 * @param id
+	 * @return
+	 */
+	Optional<Customer> findOne(Long id);
+
+	<S extends Customer> S save(S customer);
+}

jpa/java8/src/main/resources/META-INF/orm.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/xml/ns/persistence/orm_2_0.xsd" version="2.0">
+
+    <persistence-unit-metadata>
+        <persistence-unit-defaults>
+            <entity-listeners>
+                <entity-listener class="org.springframework.data.jpa.domain.support.AuditingEntityListener" />
+            </entity-listeners>
+        </persistence-unit-defaults>
+    </persistence-unit-metadata>
+
+</entity-mappings>

jpa/java8/src/test/java/example/springdata/jpa/java8/Java8IntegrationTests.java

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+/*
+ * Copyright 2013-2014 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.jpa.java8;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.junit.Assert.*;
+
+import java.util.Optional;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.test.context.ContextConfiguration;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.transaction.annotation.Transactional;
+
+/**
+ * Integration test to show the usage of Java 8 date time APIs with Spring Data JPA auditing.
+ * 
+ * @author Oliver Gierke
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@ContextConfiguration(classes = AuditingConfiguration.class)
+@Transactional
+public class Java8IntegrationTests {
+
+	@Autowired CustomerRepository repository;
+
+	@Test
+	public void providesFindOneWithOptional() {
+
+		Customer carter = repository.save(new Customer("Carter", "Beauford"));
+
+		assertThat(repository.findOne(carter.id).isPresent(), is(true));
+		assertThat(repository.findOne(carter.id + 1), is(Optional.<Customer> empty()));
+	}
+
+	@Test
+	public void auditingSetsJdk8DateTimeTypes() {
+
+		Customer customer = repository.save(new Customer("Dave", "Matthews"));
+
+		assertThat(customer.createdDate, is(notNullValue()));
+		assertThat(customer.modifiedDate, is(notNullValue()));
+	}
+}

jpa/java8/src/test/resources/logback.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<configuration>
+
+	<appender name="console" class="ch.qos.logback.core.ConsoleAppender">
+		<encoder>
+			<pattern>%d %5p %40.40c:%4L - %m%n</pattern>
+		</encoder>
+	</appender>
+
+	<logger name="org.springframework" level="info" />
+	<logger name="org.springframework.boot" level="debug" />
+	<logger name="org.hibernate.tool.hbm2ddl" level="trace" />
+
+	<root level="error">
+		<appender-ref ref="console" />
+	</root>
+
+</configuration>