Spring 3 + Hibernate + EntityManager autoscan entities

Возникают ситуации, когда entities находятся в неожиданном для Spring месте, и он не может их найти и объяснить hibernate где же их искать. Поэтому, что бы не указывать в файле persistance.xml все используемые entity, можно научить Spring искать их в заданном пакете.

Для этого необходимо создать свой bean, в котором указать пакет с enities:

<bean id="entitiesScanner" class="org.myapp.utils.EntitiesScanner">
     <property name="packagesToScan">
          <list>
               <value>org.some.greate.package</value>
          </list>
     </property>
 </bean>

А в bean LocalContainerEntityManagerFactoryBean добавить следующий аргумент:

<property name="persistenceUnitPostProcessors">
     <list>
          <ref bean="entitiesScanner"/>
     </list>
</property>

Ну и создать класс собственно EntitiesScanner:

import org.hibernate.MappingException;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.core.io.Resource;
import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
import org.springframework.core.io.support.ResourcePatternResolver;
import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
import org.springframework.core.type.classreading.MetadataReader;
import org.springframework.core.type.classreading.MetadataReaderFactory;
import org.springframework.core.type.filter.AnnotationTypeFilter;
import org.springframework.core.type.filter.TypeFilter;
import org.springframework.orm.jpa.persistenceunit.MutablePersistenceUnitInfo;
import org.springframework.orm.jpa.persistenceunit.PersistenceUnitPostProcessor;
import org.springframework.util.ClassUtils;

import javax.persistence.Embeddable;
import javax.persistence.Entity;
import javax.persistence.MappedSuperclass;
import java.io.IOException;
import java.util.HashSet;
import java.util.Set;

public class EntitiesScanner implements ApplicationContextAware, PersistenceUnitPostProcessor {

    private static final String RESOURCE_PATTERN = "**/*.class";
    private ApplicationContext applicationContext;
    private String[] packagesToScan;
    private ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();
    private TypeFilter[] entityTypeFilters = new TypeFilter[]{
            new AnnotationTypeFilter(Entity.class, false),
            new AnnotationTypeFilter(Embeddable.class, false),
            new AnnotationTypeFilter(MappedSuperclass.class, false)};

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }

    @Override
    public void postProcessPersistenceUnitInfo(MutablePersistenceUnitInfo pui) {
        String[] entities = scanPackages();
        for (String entity : entities) {
            pui.addManagedClassName(entity);
        }
    }

    /**
     * Set whether to use Spring-based scanning for entity classes in the
     * classpath instead of listing annotated classes explicitly.
     * <p/>
     * <p/>
     * <p/>
     * Default is none. Specify packages to search for autodetection of your
     * entity classes in the classpath. This is analogous to
     * <p/>
     * Spring's component-scan feature
     * (org.springframework.context.annotation.ClassPathBeanDefinitionScanner}).
     */
    public void setPackagesToScan(String[] packagesToScan) {
        this.packagesToScan = packagesToScan;
    }

    /**
     * Perform Spring-based scanning for entity classes.
     *
     * @see #setPackagesToScan
     */
    protected String[] scanPackages() {
        Set<String> entities = new HashSet<String>();
        if (this.packagesToScan != null) {
            try {
                for (String pkg : this.packagesToScan) {
                    String pattern = ResourcePatternResolver.CLASSPATH_ALL_URL_PREFIX
                            + ClassUtils.convertClassNameToResourcePath(pkg) + RESOURCE_PATTERN;
                    Resource[] resources = this.resourcePatternResolver.getResources(pattern);
                    MetadataReaderFactory readerFactory = new CachingMetadataReaderFactory(this.resourcePatternResolver);
                    for (Resource resource : resources) {
                        if (resource.isReadable()) {
                            MetadataReader reader = readerFactory.getMetadataReader(resource);
                            String className = reader.getClassMetadata().getClassName();
                            if (matchesFilter(reader, readerFactory)) {
                                entities.add(className);
                            }
                        }
                    }
                }
            } catch (IOException ex) {
                throw new MappingException("Failed to scan classpath for unlisted classes", ex);
            }
        }
        return entities.toArray(new String[entities.size()]);
    }

    /**
     * Check whether any of the configured entity type filters matches the
     * current class descriptor contained in the metadata
     * <p/>
     * reader.
     */
    private boolean matchesFilter(MetadataReader reader, MetadataReaderFactory readerFactory) throws IOException {
        if (this.entityTypeFilters != null) {
            for (TypeFilter filter : this.entityTypeFilters) {
                if (filter.match(reader, readerFactory)) {
                    return true;
                }
            }
        }
        return false;
    }
} 

via Spring, JPA, Hibernate Best Practices and Tips 

Но если вы используете spring 3.1.1, то достаточно такого конфига:

<bean id="myEmf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceProviderClass"
                  value="org.hibernate.ejb.HibernatePersistence"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter"/>
        </property>
        <property name="jpaProperties">
            <props>
                <prop key="hibernate.connection.datasource">${hibernate.connection.datasource}</prop>
                <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>
                <prop key="hibernate.show.sql">${hibernate.show.sql}</prop>
                <prop key="hibernate.dialect">${hibernate.dialect}</prop>
            </props>
        </property>

        <property name="packagesToScan">
            <list>
                <value>com.package.enities</value>
            </list>
        </property>
    </bean>

При этом от pesistence.xml можно полностью отказаться.