Initial draft of Envers support for Spring Data JPA.

Added an implementation of the Spring Data Commons historiography API based on Hibernate Envers. The implementation is a contribution of @hygl to a large degree.

.gitignore

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+.classpath
+.project
+.springBeans
+.settings/
+target/

pom.xml

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+<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>
+	<groupId>org.springframework.data</groupId>
+	<artifactId>spring-data-envers</artifactId>
+	<version>0.1.0.BUILD-SNAPSHOT</version>
+
+	<properties>
+		<spring.version>3.1.1.RELEASE</spring.version>
+		<spring.data.jpa.version>1.1.0.BUILD-SNAPSHOT</spring.data.jpa.version>
+		<file.encoding>UTF-8</file.encoding>
+	</properties>
+
+	<repositories>
+		<repository>
+			<id>spring-releases</id>
+			<url>http://repo.springsource.org/libs-release</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</repository>
+	</repositories>
+
+	<pluginRepositories>
+		<pluginRepository>
+			<id>spring-plugins</id>
+			<url>http://repo.springsource.org/libs-plugin</url>
+			<snapshots>
+				<enabled>false</enabled>
+			</snapshots>
+		</pluginRepository>
+	</pluginRepositories>
+
+	<developers>
+		<developer>
+			<name>Oliver Gierke</name>
+			<email>ogierke@vmware.com</email>
+			<organization>SpringSource, a division of VMware</organization>
+			<organizationUrl>www.springsource.org</organizationUrl>
+		</developer>
+		<developer>
+			<name>Philip Huegelmeyer</name>
+			<email>philip.huegelmeyer@ble.de</email>
+			<organization>BLE</organization>
+			<organizationUrl>www.ble.de</organizationUrl>
+		</developer>
+	</developers>
+
+	<scm>
+		<url>https://github.com/SpringSource/spring-data-envers</url>
+	</scm>
+
+	<dependencies>
+
+		<dependency>
+			<groupId>org.springframework.data</groupId>
+			<artifactId>spring-data-jpa</artifactId>
+			<version>${spring.data.jpa.version}</version>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-orm</artifactId>
+			<version>${spring.version}</version>
+		</dependency>
+
+		<!-- Test -->
+		<dependency>
+			<groupId>junit</groupId>
+			<artifactId>junit</artifactId>
+			<version>4.8.2</version>
+			<scope>test</scope>
+		</dependency>
+
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-test</artifactId>
+			<version>${spring.version}</version>
+		</dependency>
+
+		<!-- Logging -->
+
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>slf4j-api</artifactId>
+			<version>1.6.1</version>
+			<scope>runtime</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>jcl-over-slf4j</artifactId>
+			<version>1.6.1</version>
+			<scope>runtime</scope>
+		</dependency>
+		<dependency>
+			<groupId>log4j</groupId>
+			<artifactId>log4j</artifactId>
+			<version>1.2.16</version>
+		</dependency>
+		<dependency>
+			<groupId>org.slf4j</groupId>
+			<artifactId>slf4j-log4j12</artifactId>
+			<version>1.6.1</version>
+		</dependency>
+
+		<dependency>
+			<groupId>org.hibernate</groupId>
+			<artifactId>hibernate-envers</artifactId>
+			<version>4.0.1.Final</version>
+		</dependency>
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+			<version>1.3.157</version>
+		</dependency>
+		<dependency>
+			<groupId>cglib</groupId>
+			<artifactId>cglib</artifactId>
+			<version>2.2</version>
+		</dependency>
+		<dependency>
+			<groupId>joda-time</groupId>
+			<artifactId>joda-time</artifactId>
+			<version>2.1</version>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-war-plugin</artifactId>
+				<version>2.1.1</version>
+				<configuration>
+					<failOnMissingWebXml>false</failOnMissingWebXml>
+				</configuration>
+			</plugin>
+		</plugins>
+	</build>
+</project>

readme.md

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+# Spring Data Envers #
+
+This project is an extension of the [Spring Data JPA](http://github.com/SpringSource/spring-data-jpa) project to allow access to entity revisions managed by Hibernate Envers. The sources mostly originate from a contribution of Philip Hügelmeyer [@hygl](https://github.com/hygl).
+
+The core feature of the module consists of an implementation of the `RevisionRepository` of Spring Data Commons.
+
+```java
+public interface RevisionRepository<T, ID extends Serializable, N extends Number & Comparable<N>> {
+
+	Revision<N, T> findLastChangeRevision(ID id);
+
+	Revisions<N, T> findRevisions(ID id);
+
+	Page<Revision<N, T>> findRevisions(ID id, Pageable pageable);
+}
+```
+
+You can pull in this functionality to your repositories by simply additionally extending the interface just mentioned:
+
+
+```java
+interface PersonRepository extend RevisionRepository<Person, Long, Long>, CrudRepository<Person, Long> {
+
+  // Your query methods go here
+}
+```
+
+To successfully activate the Spring Data Envers repository factory use the Spring Data JPA repositories namespace element's `factory-class` attribute:
+
+```xml
+<jpa:repositories base-package="com.acme.repositories"
+                  factory-class="….EnversRevisionRepositoryFactoryBean" />
+```
+
+# Contributing to the project
+
+If you're an Eclipse user make sure you activate automatic application of the formatter (located at `etc/eclipse-formatter.xml`) and activate automatic formatting and organizing imports on save.

src/main/java/org/springframework/data/envers/repository/support/DefaultRevisionEntityInformation.java

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+/*
+ * Copyright 2012 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 org.springframework.data.envers.repository.support;
+
+import org.hibernate.envers.DefaultRevisionEntity;
+import org.springframework.data.repository.history.support.RevisionEntityInformation;
+
+/**
+ * {@link RevisionEntityInformation} for {@link DefaultRevisionEntity}.
+ * 
+ * @author Oliver Gierke
+ */
+class DefaultRevisionEntityInformation implements RevisionEntityInformation {
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.repository.history.support.RevisionEntityInformation#getRevisionNumberType()
+	 */
+	public Class<?> getRevisionNumberType() {
+		return Integer.class;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.repository.history.support.RevisionEntityInformation#isDefaultRevisionEntity()
+	 */
+	public boolean isDefaultRevisionEntity() {
+		return true;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.repository.history.support.RevisionEntityInformation#getRevisionEntityClass()
+	 */
+	public Class<?> getRevisionEntityClass() {
+		return DefaultRevisionEntity.class;
+	}
+}

src/main/java/org/springframework/data/envers/repository/support/DefaultRevisionMetadata.java

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+/*
+ * Copyright 2012 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 org.springframework.data.envers.repository.support;
+
+import org.hibernate.envers.DefaultRevisionEntity;
+import org.joda.time.DateTime;
+import org.springframework.data.history.RevisionMetadata;
+import org.springframework.util.Assert;
+
+/**
+ * {@link RevisionMetadata} working with a {@link DefaultRevisionEntity}.
+ * 
+ * @author Oliver Gierke
+ * @author Philip Huegelmeyer
+ */
+public class DefaultRevisionMetadata implements RevisionMetadata<Integer> {
+
+	private final DefaultRevisionEntity entity;
+
+	/**
+	 * Creates a new {@link DefaultRevisionMetadata}.
+	 * 
+	 * @param entity must not be {@literal null}.
+	 */
+	public DefaultRevisionMetadata(DefaultRevisionEntity entity) {
+
+		Assert.notNull(entity);
+		this.entity = entity;
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.history.RevisionMetadata#getRevisionNumber()
+	 */
+	public Integer getRevisionNumber() {
+		return entity.getId();
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.history.RevisionMetadata#getRevisionDate()
+	 */
+	public DateTime getRevisionDate() {
+		return new DateTime(entity.getTimestamp());
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * @see org.springframework.data.history.RevisionMetadata#getDelegate()
+	 */
+	@SuppressWarnings("unchecked")
+	public <T> T getDelegate() {
+		return (T) entity;
+	}
+}

src/main/java/org/springframework/data/envers/repository/support/EnversRevisionRepository.java

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+/*
+ * Copyright 2012 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 org.springframework.data.envers.repository.support;
+
+import java.io.Serializable;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.repository.NoRepositoryBean;
+import org.springframework.data.repository.history.RevisionRepository;
+
+/**
+ * Convenience interface to allow pulling in {@link JpaRepository} and {@link RevisionRepository} functionality in one
+ * go.
+ * 
+ * @author Oliver Gierke
+ */
+@NoRepositoryBean
+public interface EnversRevisionRepository<T, ID extends Serializable, N extends Number & Comparable<N>> extends
+		RevisionRepository<T, ID, N>, JpaRepository<T, ID> {
+
+}