DATAJPA-38 - Introduced MergingPersistenceUnitManager.

src/docbkx/reference/jpa.xml

@@ -708,4 +708,28 @@ public interface UserRepository extends JpaRepository<User, Long> {
       thus allow seemless tracking of the auditor.</para>
     </simplesect>
   </section>
+
+  <section id="jpa.misc">
+    <title>Miscellaneous</title>
+
+    <section>
+      <title>Merging persistence units</title>
+
+      <para>Spring supports ahving multiple persistence units out of the box.
+      But sometimes you might wanna modularize your application but make sure
+      that all these module run inside a single persistence unit at runtime.
+      To do so Spring Data JPA offers a PersistenceUnitManager implementation
+      that automatically merges persistence units based on their name.</para>
+
+      <example>
+        <title>Using MergingPersistenceUnitmanager</title>
+
+        <para><programlisting language="xml">&lt;bean class="….LocalContainerEntityManagerFactoryBean"&gt;
+  &lt;property name="persistenceUnitManager"&gt;
+    &lt;bean class="….MergingPersistenceUnitManager" /&gt;
+  &lt;/property
+&lt;/bean&gt;</programlisting></para>
+      </example>
+    </section>
+  </section>
 </chapter>

src/main/java/org/springframework/data/jpa/support/MergingPersistenceUnitManager.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2011 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.jpa.support;
+
+import java.net.URL;
+
+import javax.persistence.spi.PersistenceUnitInfo;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager;
+import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo;
+
+
+/**
+ * Extends {@link DefaultPersistenceUnitManager} to merge configurations of one
+ * persistence unit residing in multiple {@code persistence.xml} files into one.
+ * This is necessary to allow the declaration of entities in seperate modules.
+ * 
+ * @author Oliver Gierke
+ * @see http://jira.springframework.org/browse/SPR-2598
+ */
+public class MergingPersistenceUnitManager extends
+        DefaultPersistenceUnitManager {
+
+    private static final Logger log = LoggerFactory
+            .getLogger(MergingPersistenceUnitManager.class);
+
+
+    /*
+     * (non-Javadoc)
+     * 
+     * @see
+     * org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager
+     * #
+     * postProcessPersistenceUnitInfo(org.springframework.orm.jpa.persistenceunit
+     * .MutablePersistenceUnitInfo)
+     */
+    @Override
+    protected void postProcessPersistenceUnitInfo(MutablePersistenceUnitInfo pui) {
+
+        // Invoke normal post processing
+        super.postProcessPersistenceUnitInfo(pui);
+
+        PersistenceUnitInfo oldPui =
+                getPersistenceUnitInfo(pui.getPersistenceUnitName());
+
+        if (oldPui != null) {
+            postProcessPersistenceUnitInfo(pui, oldPui);
+        }
+    }
+
+
+    void postProcessPersistenceUnitInfo(MutablePersistenceUnitInfo pui,
+            PersistenceUnitInfo oldPui) {
+
+        for (URL url : oldPui.getJarFileUrls()) {
+
+            // Add jar file url to PUI
+            if (!pui.getJarFileUrls().contains(url)) {
+                log.debug("Adding {} to persistence units", url);
+                pui.addJarFileUrl(url);
+            }
+        }
+
+        pui.addJarFileUrl(oldPui.getPersistenceUnitRootUrl());
+    }
+}

src/test/java/org/springframework/data/jpa/support/MergingPersistenceUnitManagerUnitTests.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2011 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.jpa.support;
+
+import static org.mockito.Mockito.*;
+
+import java.net.MalformedURLException;
+import java.net.URL;
+import java.util.Arrays;
+
+import javax.persistence.spi.PersistenceUnitInfo;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.runners.MockitoJUnitRunner;
+import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo;
+
+
+/**
+ * Unit test for {@link MergingPersistenceUnitManager}.
+ * 
+ * @author Oliver Gierke
+ */
+@RunWith(MockitoJUnitRunner.class)
+public class MergingPersistenceUnitManagerUnitTests {
+
+    @Mock
+    PersistenceUnitInfo oldInfo;
+
+    @Mock
+    MutablePersistenceUnitInfo newInfo;
+
+
+    @Test
+    public void addsUrlFromOldPUItoNewOne() throws MalformedURLException {
+
+        MergingPersistenceUnitManager manager =
+                new MergingPersistenceUnitManager();
+        URL jarFileUrl = new URL("file:foo/bar");
+
+        when(oldInfo.getJarFileUrls()).thenReturn(Arrays.asList(jarFileUrl));
+        manager.postProcessPersistenceUnitInfo(newInfo, oldInfo);
+        verify(newInfo).addJarFileUrl(jarFileUrl);
+    }
+}