Added support to allow manually declaring a EntityManagerFactoryBean.

Added the necessary @ConditionalOnMissingBean annotations to allow selectively declaring an EntityManagerFactoryBean, a JpaVendorAdapter or a PlatformTransactionManager. Especially the first one might be necessary to make sure the persistence provider evaluates an orm.xml. This unfortunately rules out using the packages to scan feature of Spring's LCEMFB.

I've filed https://jira.springsource.org/browse/SPR-11260 to potentially remove the need for this workaround in Spring itself.

spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/orm/jpa/JpaBaseConfiguration.java

@@ -34,6 +34,7 @@ import org.springframework.context.EnvironmentAware;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
+import org.springframework.orm.jpa.EntityManagerFactoryInfo;
 import org.springframework.orm.jpa.JpaTransactionManager;
 import org.springframework.orm.jpa.JpaVendorAdapter;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
@@ -51,6 +52,7 @@ import org.springframework.web.servlet.config.annotation.WebMvcConfigurerAdapter
  * 
  * @author Phillip Webb
  * @author Dave Syer
+ * @author Oliver Gierke
  */
 public abstract class JpaBaseConfiguration implements BeanFactoryAware, EnvironmentAware {
 
@@ -64,14 +66,16 @@ public abstract class JpaBaseConfiguration implements BeanFactoryAware, Environm
 	}
 
 	@Bean
+	@ConditionalOnMissingBean(PlatformTransactionManager.class)
 	public PlatformTransactionManager transactionManager() {
-		return new JpaTransactionManager(entityManagerFactory().getObject());
+		return new JpaTransactionManager();
 	}
 
 	@Bean
-	public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
+	@ConditionalOnMissingBean(EntityManagerFactoryInfo.class)
+	public LocalContainerEntityManagerFactoryBean entityManagerFactory(JpaVendorAdapter jpaVendorAdapter) {
 		LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
-		entityManagerFactoryBean.setJpaVendorAdapter(jpaVendorAdapter());
+		entityManagerFactoryBean.setJpaVendorAdapter(jpaVendorAdapter);
 		entityManagerFactoryBean.setDataSource(getDataSource());
 		entityManagerFactoryBean.setPackagesToScan(getPackagesToScan());
 		entityManagerFactoryBean.getJpaPropertyMap().putAll(
@@ -81,6 +85,7 @@ public abstract class JpaBaseConfiguration implements BeanFactoryAware, Environm
 	}
 
 	@Bean
+	@ConditionalOnMissingBean(JpaVendorAdapter.class)
 	public JpaVendorAdapter jpaVendorAdapter() {
 		AbstractJpaVendorAdapter adapter = createJpaVendorAdapter();
 		adapter.setShowSql(this.environment.getProperty("show-sql", Boolean.class, true));

spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/orm/jpa/AbstractJpaAutoConfigurationTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.autoconfigure.orm.jpa;
 
+import java.util.Collections;
 import java.util.Map;
 
 import javax.sql.DataSource;
@@ -27,6 +28,7 @@ import org.springframework.boot.autoconfigure.ComponentScanDetectorConfiguration
 import org.springframework.boot.autoconfigure.PropertyPlaceholderAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.DataSourceTransactionManagerAutoConfiguration;
 import org.springframework.boot.autoconfigure.jdbc.EmbeddedDataSourceConfiguration;
+import org.springframework.boot.autoconfigure.orm.jpa.AbstractJpaAutoConfigurationTests.TestConfigurationWithTransactionManager.CustomJpaTransactionManager;
 import org.springframework.boot.autoconfigure.orm.jpa.test.City;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
@@ -34,11 +36,14 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.ComponentScan;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.orm.jpa.JpaTransactionManager;
+import org.springframework.orm.jpa.JpaVendorAdapter;
 import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
 import org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter;
 import org.springframework.orm.jpa.support.OpenEntityManagerInViewInterceptor;
+import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
 
+import static org.hamcrest.CoreMatchers.*;
 import static org.hamcrest.Matchers.equalTo;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotNull;
@@ -130,9 +135,35 @@ public abstract class AbstractJpaAutoConfigurationTests {
 		assertThat(map.get("a"), equalTo((Object) "b"));
 		assertThat(map.get("c"), equalTo((Object) "d"));
 	}
+	
+	@Test
+	public void usesManuallyDefinedEntityManagerFactoryBeanIfAvailable() {
+		
+		setupTestConfiguration(TestConfigurationWithEntityManagerFactory.class);
+		this.context.refresh();
+		
+		LocalContainerEntityManagerFactoryBean factoryBean = this.context.getBean(LocalContainerEntityManagerFactoryBean.class);
+		Map<String, Object> map = factoryBean.getJpaPropertyMap();
+		assertThat(map.get("configured"), is((Object) "manually"));
+	}
+	
+	@Test
+	public void usesManuallyDefinedTransactionManagerBeanIfAvailable() {
+		
+		setupTestConfiguration(TestConfigurationWithTransactionManager.class);
+		this.context.refresh();
+		
+		PlatformTransactionManager txManager = this.context.getBean(PlatformTransactionManager.class);
+		assertThat(txManager, is(instanceOf(CustomJpaTransactionManager.class)));
+	}
 
 	protected void setupTestConfiguration() {
-		this.context.register(TestConfiguration.class,
+		setupTestConfiguration(TestConfiguration.class);
+	}
+	
+	protected void setupTestConfiguration(Class<?> configClass) {
+		
+		this.context.register(configClass,
 				ComponentScanDetectorConfiguration.class,
 				EmbeddedDataSourceConfiguration.class,
 				PropertyPlaceholderAutoConfiguration.class, getAutoConfigureClass());
@@ -156,7 +187,34 @@ public abstract class AbstractJpaAutoConfigurationTests {
 		public OpenEntityManagerInViewFilter openEntityManagerInViewFilter() {
 			return new OpenEntityManagerInViewFilter();
 		}
-
 	}
-
+	
+	@Configuration
+	protected static class TestConfigurationWithEntityManagerFactory extends TestConfiguration {
+		
+		@Bean
+		public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter adapter) {
+			
+			LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
+			factoryBean.setJpaVendorAdapter(adapter);
+			factoryBean.setDataSource(dataSource);
+			factoryBean.setPersistenceUnitName("manually-configured");
+			factoryBean.setJpaPropertyMap(Collections.singletonMap("configured", "manually"));
+			return factoryBean;
+		}
+	}
+	
+	@Configuration
+	@ComponentScan(basePackageClasses = { City.class })
+	protected static class TestConfigurationWithTransactionManager {
+		
+		@Bean
+		public PlatformTransactionManager transactionManager() {
+			return new CustomJpaTransactionManager();
+		}
+		
+		static class CustomJpaTransactionManager extends JpaTransactionManager {
+			
+		}
+	}
 }

spring-boot-autoconfigure/src/test/resources/META-INF/persistence.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<persistence version="2.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
+	<persistence-unit name="manually-configured">
+		<class>org.springframework.boot.autoconfigure.orm.jpa.test.City</class>
+		<exclude-unlisted-classes>true</exclude-unlisted-classes>
+	</persistence-unit>
+</persistence>