Work on DAO example.

dao/src/main/java/com/iluwatar/DaoBase.java

@@ -1,24 +1,131 @@
 package com.iluwatar;
 
-public abstract class DaoBase<E extends BaseEntity> {
+import java.lang.reflect.ParameterizedType;
+import java.util.List;
 
+import org.hibernate.Criteria;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.criterion.Restrictions;
+
+public abstract class DaoBase<E extends BaseEntity> {
+	
+	@SuppressWarnings("unchecked")
+	protected Class<E> persistentClass = (Class<E>) ((ParameterizedType) getClass()
+            .getGenericSuperclass()).getActualTypeArguments()[0];
+
+	protected final SessionFactory sessionFactory = createSessionFactory();
+	
+	private SessionFactory createSessionFactory() {
+    	SessionFactory sessionFactory = new Configuration()
+  	  		.addAnnotatedClass(Wizard.class)
+  	  		.addAnnotatedClass(Spellbook.class)
+  	  		.addAnnotatedClass(Spell.class)
+  	  		.setProperty("hibernate.dialect", "org.hibernate.dialect.H2Dialect")
+  	  		.setProperty("hibernate.connection.url", "jdbc:h2:mem:test;DB_CLOSE_DELAY=-1")
+  	  		.setProperty("hibernate.current_session_context_class", "thread")
+  	  		.setProperty("hibernate.show_sql", "true")
+  	  		.setProperty("hibernate.hbm2ddl.auto", "create")
+  	  		.buildSessionFactory();
+    	return sessionFactory;
+	}
+	
+	private Session getSession() {
+		return sessionFactory.openSession();
+	}
+	
 	E find(Long id) {
-		
+		Session session = getSession();
+		Transaction tx = null;
+		E result = null;
+		try {
+			tx = session.beginTransaction();
+			Criteria criteria = sessionFactory.getCurrentSession().createCriteria(persistentClass);
+			criteria.add(Restrictions.idEq(id));
+			result = (E) criteria.uniqueResult();
+			tx.commit();
+		}
+		catch (Exception e) {
+			if (tx!=null) tx.rollback();
+			throw e;
+		}
+		finally {
+			session.close();
+		}		
+		return result;
 	}
 	
-	void persist(E e) {
-		
+	void persist(E entity) {
+		Session session = getSession();
+		Transaction tx = null;
+		try {
+			tx = session.beginTransaction();
+			session.persist(entity);
+			tx.commit();
+		}
+		catch (Exception e) {
+			if (tx!=null) tx.rollback();
+			throw e;
+		}
+		finally {
+			session.close();
+		}		
 	}
 	
-	E merge(E e) {
-		
+	E merge(E entity) {
+		Session session = getSession();
+		Transaction tx = null;
+		E result = null;
+		try {
+			tx = session.beginTransaction();
+			result = (E) session.merge(entity);
+			tx.commit();
+		}
+		catch (Exception e) {
+			if (tx!=null) tx.rollback();
+			throw e;
+		}
+		finally {
+			session.close();
+		}		
+		return result;
 	}
 	
-	void remove(E e) {
-		
+	void delete(E entity) {
+		Session session = getSession();
+		Transaction tx = null;
+		try {
+			tx = session.beginTransaction();
+			session.delete(entity);
+			tx.commit();
+		}
+		catch (Exception e) {
+			if (tx!=null) tx.rollback();
+			throw e;
+		}
+		finally {
+			session.close();
+		}		
 	}
 	
 	List<E> findAll() {
-		
+		Session session = getSession();
+		Transaction tx = null;
+		List<E> result = null;
+		try {
+			tx = session.beginTransaction();
+			Criteria criteria = session.createCriteria(persistentClass);
+			result = criteria.list();
+		}
+		catch (Exception e) {
+			if (tx!=null) tx.rollback();
+			throw e;
+		}
+		finally {
+			session.close();
+		}		
+		return result;
 	}
 }