Generic Hibernate DAO

I intended to create a post about Hibernate subselects, but I decided to post the whole Generic Hibernate DAO.

A short briefing of the surrounding system.
I have different child classes of "BasicObject" they all got an according "ObjectRef" which is a small object (id,name,locale) used as reference on the larger BasicObject (like in a tree or document content). The reference object and the BasicObject have the same id (UUID).
The whole software is a server/client application using Eclipse EMF to model, generate and handle the business objects, Eclipse Riena for remoting and Hibernate/Teneo for persistence. Ohh and for sure Eclipse RCP as client. Isn't the Eclipse movement great :-).

To the subselects, I used them in the search(...) method.
The search() restricts the select on BasicObject fields and returns a list of ObjectRefs. This saves us a lot of bandwidth since BasicObjects can have n fields of any size and the ObjectRef only has three.
The first query (DetachedCriteria) which is restricted based on the BasicObject fields (i.e. name LIKE 'test' AND description LIKE 'Start%') is used to restrict the actual query on ObjectRef using the result (ids) of the DetachedCriteria query.

As for the rest of the class, it's a Generic Hibernate Data Access Object even though the name ends in "Service". I just combined the Service and DAO, since in our case, it doesn't make sense to separate them.
Maybe the create() method is a bit confusing, that's because we use the Eclipse Modeling Framework to create the business objects.

BasicObjectService.java

/*******************************************************************************
 * $RCSfile: $ Copyright (c) 2007 henzler informatik gmbh, CH-4106 Therwil
 *******************************************************************************/
package com.softmodeler.service.impl;

import java.lang.reflect.ParameterizedType;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import javax.persistence.EntityManager;
import javax.persistence.EntityTransaction;

import org.eclipse.emf.ecore.EClass;
import org.eclipse.emf.ecore.EPackage;
import org.eclipse.emf.ecore.EStructuralFeature;
import org.eclipse.emf.ecore.util.EcoreUtil;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.criterion.DetachedCriteria;
import org.hibernate.criterion.Property;
import org.hibernate.criterion.Restrictions;

import com.softmodeler.model.BasicObject;
import com.softmodeler.model.ObjectRef;
import com.softmodeler.service.IBasicObjectService;
import com.softmodeler.service.ModelUtil;

/**
 * The BasicObjectService implements the default handling for all BasicObject sub services
 * 
 * @author created by Author: fdo, last update by $Author: $
 * @version $Revision: $, $Date: $
 */
public abstract class BasicObjectService implements
  IBasicObjectService {
 /** The Hibernate Session */
 protected Session session;
 /** The Entity Manager */
 protected EntityManager entityManager;

 /**
  * The constructor
  * 
  * @param session
  * @param entityManager
  */
 public BasicObjectService(Session session, EntityManager entityManager) {
  this.session = session;
  this.entityManager = entityManager;
 }

 /**
  * Returns the class of the BasicObject
  * 
  * @return
  */
 @SuppressWarnings("unchecked")
 protected Class getObjectClass() {
  return (Class) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[0];

 }

 /**
  * Returns the class of the ObjectRef
  * 
  * @return
  */
 @SuppressWarnings("unchecked")
 protected Class getRefClass() {
  return (Class) ((ParameterizedType) getClass().getGenericSuperclass()).getActualTypeArguments()[1];
 }

 /**
  * Begins a Transaction
  * 
  * @return
  */
 protected EntityTransaction beginTransaction() {
  EntityTransaction transaction = entityManager.getTransaction();
  if (!transaction.isActive()) {
   transaction.begin();
  }
  return transaction;
 }

 @SuppressWarnings("unchecked")
 @Override
 public K create() {
  // create the objects using the according EPackage
  EPackage modelPackage = ModelUtil.getModelPackage();
  EPackage refPackage = ModelUtil.getRefPackage();
  EClass objectEClass = (EClass) modelPackage.getEClassifier(getObjectClass().getSimpleName());
  EClass refEClass = (EClass) refPackage.getEClassifier(getRefClass().getSimpleName());
  K object = (K) modelPackage.getEFactoryInstance().create(objectEClass);
  V ref = (V) refPackage.getEFactoryInstance().create(refEClass);

  // set the ids
  object.setId(EcoreUtil.generateUUID());
  ref.setId(object.getId());

  // store objects in the database
  EntityTransaction transaction = beginTransaction();
  session.save(object);
  session.save(ref);
  transaction.commit();
  return object;
 }

 @SuppressWarnings("unchecked")
 @Override
 public void delete(K object) {
  EntityTransaction transaction = beginTransaction();

  // load first, to prevent delete problems
  Criteria criteria = session.createCriteria(getObjectClass());
  criteria.add(Restrictions.eq(ID, object.getId()));
  K loadedObject = (K) criteria.uniqueResult();

  Criteria criteriaRef = session.createCriteria(getRefClass());
  criteriaRef.add(Restrictions.eq(ID, object.getId()));
  V loadedRef = (V) criteria.uniqueResult();

  session.delete(loadedObject);
  session.delete(loadedRef);
  transaction.commit();
 }

 @SuppressWarnings("unchecked")
 @Override
 public List findAllRefs() {
  Criteria critica = session.createCriteria(getRefClass());
  return critica.list();
 }

 @SuppressWarnings("unchecked")
 @Override
 public K findById(String uuid) {
  Criteria criteria = session.createCriteria(getObjectClass());
  criteria.add(Restrictions.eq(ID, uuid));
  return (K) criteria.uniqueResult();
 }

 @SuppressWarnings("unchecked")
 @Override
 public K findByRef(V ref) {
  Criteria criteria = session.createCriteria(getObjectClass());
  criteria.add(Restrictions.eq(ID, ref.getId()));
  return (K) criteria.uniqueResult();
 }

 @SuppressWarnings("unchecked")
 @Override
 public V getRef(K object) {
  Criteria criteria = session.createCriteria(getRefClass());
  criteria.add(Restrictions.eq(ID, object.getId()));
  return (V) criteria.uniqueResult();
 }

 @Override
 public void store(K object) {
  EntityTransaction transaction = beginTransaction();
  entityManager.merge(object);
  transaction.commit();
 }

 @Override
 public void storeRef(ObjectRef ref) {
  EntityTransaction transaction = beginTransaction();
  entityManager.merge(ref);
  transaction.commit();
 }


 @SuppressWarnings("unchecked")
 @Override
 public List search(Map fieldValues) {
  DetachedCriteria objCritica = DetachedCriteria.forEntityName(getObjectClass().getSimpleName(), "obj");
  for (String field : fieldValues.keySet()) {
   objCritica.add(Restrictions.like(field, fieldValues.get(field)));
  }
  objCritica.setProjection(Property.forName(ID));
  Criteria criteria = session.createCriteria(getRefClass());
  criteria.add(Property.forName(ID).in(objCritica));
  return criteria.list();
 }
}

Here the according interface:
IBasicObjectService.java

/*******************************************************************************
 * $RCSfile: $ Copyright (c) 2007 henzler informatik gmbh, CH-4106 Therwil
 *******************************************************************************/
package com.softmodeler.service;

import java.util.List;
import java.util.Map;

import com.softmodeler.model.BasicObject;
import com.softmodeler.model.ObjectRef;

/**
 * @author created by Author: fdo, last update by $Author: $
 * @version $Revision: $, $Date: $
 */
public interface IBasicObjectService {
 /** Id field */
 public static final String ID = "id";

 /**
  * Creates, stores and returns an object
  * 
  * @return
  */
 K create();

 /**
  * Creates, stores and returns an object reference
  * 
  * @return
  */
 V getRef(K object);

 /**
  * Deletes an object
  * 
  * @param object
  */
 void delete(K object);

 /**
  * Stores an object
  * 
  * @param object
  */
 void store(K object);

 /**
  * Stores a reference object
  * 
  * @param ref
  */
 void storeRef(V ref);

 /**
  * Finds an object, by it's uuid
  * 
  * @param AutoJobRef
  * @return
  */
 K findById(String uuid);

 /**
  * Finds an object, using it's reference object
  * 
  * @param ref
  * @return
  */
 K findByRef(V ref);

 /**
  * Returns a list containing all ref objects
  * 
  * @return
  */
 List findAllRefs();

 /**
  * Searches ObjectRefs using the passed map to create the query
  * 
  * @param fieldValues field name => value
  * @return
  */
 List search(Map fieldValues);
}

Spring Dynamic Modules and Hibernate

I'm currently working on a Sourceforge project.
On the server side I want to use Spring DM and Hibernate.
Eclipse RCP and Spring DM builds the client.

I spent the last few evenings trying and searching for a working Spring DM/Hibernate example. I had a lot of classloading issues.
Yesterday I got it to work, you can download the plug-in here.

It's a simple application handling a User object and using HSQL as database.

I added all the dependent jars in the /lib directory. You can create separated plug-ins for them if you want.
Here a list of all the jar files, because thats where I had my problems:

• cglib-nodep-2.1_3.jar
• commons-collections.jar
• commons-dbcp.jar
• commons-pool.jar
• dom4j-1.6.1.jar
• hibernate3.jar
• hsqldb.jar
• jta.jar
• spring-core.jar
• spring-jdbc.jar
• spring-orm.jar
• spring-tx.jar // why is the org.springframework.dao package in this jar?
  

You can access the service in the Test class:

package com.blogspot.swissdev.springservice;

import org.osgi.framework.BundleContext;

/**
*
* @author Flavio Donze 
*/
public class Test {

  private BundleContext context = Activator.getDefault().getContext();

  public void start() {
      System.out.println("starting the test...");

      UserService service = (UserService) context.getService(context.getServiceReference(UserService.class.getName()));
   
      User user = (User) context.getService(context.getServiceReference(User.class.getName()));
      user.setPassword("pass");
      user.setUsername("user");
      service.store(user);

      for (User u : service.findAll())
      {
          System.out.println("User: "+u.getId() + ", " + u.getUsername() + ", " + u.getPassword());
      }
  }
}

And here is my Spring configuration:

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">

  <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
      <property name="location" value="META-INF/spring/database.properties"/>
  </bean>

  <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
      <property name="driverClassName" value="${jdbc.driverClassName}"/>
      <property name="url" value="${jdbc.url}"/>
      <property name="username" value="${jdbc.username}"/>
      <property name="password" value="${jdbc.password}"/>
  </bean>

  <bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
      <property name="dataSource" ref="dataSource"/>
      <property name="mappingResources">
      <list>
          <value>User.hbm.xml</value>
      </list>
      </property>
      <property name="hibernateProperties">
          <props>
              <prop key="hibernate.dialect">${hibernate.dialect}</prop>
              <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
              <prop key="hibernate.hbm2ddl.auto">${hibernate.hbm2ddl.auto}</prop>
          </props>
      </property>
  </bean>

  <bean id="test" init-method="start" class="com.blogspot.swissdev.springservice.Test"/>

  <!-- USER beans, POJO, DAO, Service -->
  <bean id="user" class="com.blogspot.swissdev.springservice.UserImpl" scope="prototype">
  </bean>

  <bean id="userDao" class="com.blogspot.swissdev.springservice.UserDaoImpl">
      <property name="sessionFactory" ref="sessionFactory"/>
  </bean>

  <bean id="userService" class="com.blogspot.swissdev.springservice.UserServiceImpl">
      <property name="userDao" ref="userDao"/>
  </bean>

</beans>

Since I just wanted to get Spring DM and Hibernate to work, I didn't really test the rest, just in case you encounter some bugs.

To setup your workspace with Spring DM read the first part of my previous post.

For this example I used:
Eclipse 3.4 RC3
Spring Dynamic Modules for OSGi(tm) 1.0.2