Work on DAO example.

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

@@ -2,39 +2,27 @@ package com.iluwatar;
 
 import java.util.List;
 
-import org.hibernate.Query;
-import org.hibernate.Session;
-import org.hibernate.SessionFactory;
-import org.hibernate.cfg.Configuration;
 
-public class App 
-{
+public class App {
     public static void main( String[] args ) {   
+    	WizardDao dao = new WizardDao();
+    	persistData(dao);
+    	queryData(dao);
+    }
     
-    	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();
-    	  
-    	  Session session = sessionFactory.getCurrentSession();
-    	  session.beginTransaction();
-    	  Wizard wizard = new Wizard();
-    	  wizard.setFirstName("Jugga");
-    	  Spellbook spellbook = new Spellbook();
-    	  Spell spell = new Spell();
+    public static void persistData(WizardDao dao) {
+    	Spell spell = new Spell("Fireball");
+    	Spellbook spellbook = new Spellbook("Book of fire");
     	spellbook.getSpells().add(spell);
+    	Wizard wizard = new Wizard("Jugga");
     	wizard.getSpellbooks().add(spellbook);
-    	  session.persist(wizard);
-    	  Query query = session.createQuery("from Wizard");
-    	  List<?> list = query.list();
-    	  Wizard p1 = (Wizard) list.get(0);
-    	  System.out.println(String.format("id=%d firstName=%s", p1.getId(), p1.getFirstName()));
-    	  session.getTransaction().commit();    	
+    	dao.persist(wizard);
+    }
+    
+    public static void queryData(WizardDao dao) {
+    	List<Wizard> wizards = dao.findAll();
+    	for (Wizard w: wizards) {
+    		System.out.println(w);
+    	}
     }
 }

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

@@ -1,24 +1,131 @@
 package com.iluwatar;
 
+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;
 	}
 }

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

@@ -11,6 +11,14 @@ public class Spell extends BaseEntity {
 	
 	private String name;
 	
+	public Spell() {
+	}
+	
+	public Spell(String name) {
+		this();
+		this.name = name;
+	}
+
 	@ManyToOne
 	@JoinColumn(name="SPELLBOOK_ID_FK", referencedColumnName="ID")
 	private Spellbook spellbook;
@@ -22,4 +30,9 @@ public class Spell extends BaseEntity {
 	public void setName(String name) {
 		this.name = name;
 	}
+	
+	@Override
+	public String toString() {
+		return name;
+	}	
 }

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

@@ -0,0 +1,5 @@
+package com.iluwatar;
+
+public class SpellDao extends DaoBase<Spell> {
+
+}

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

@@ -18,6 +18,11 @@ public class Spellbook extends BaseEntity {
 		spells = new HashSet<Spell>();
 	}
 	
+	public Spellbook(String name) {
+		this();
+		this.name = name;
+	}
+
 	private String name;
 
 	@ManyToOne
@@ -50,4 +55,9 @@ public class Spellbook extends BaseEntity {
 	public void setSpells(Set<Spell> spells) {
 		this.spells = spells;
 	}
+	
+	@Override
+	public String toString() {
+		return name;
+	}	
 }

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

@@ -0,0 +1,5 @@
+package com.iluwatar;
+
+public class SpellbookDao extends DaoBase<Spellbook> {
+
+}

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

@@ -16,17 +16,22 @@ public class Wizard extends BaseEntity {
 		spellbooks = new HashSet<Spellbook>();
 	}
 	
-	private String firstName;
+	public Wizard(String name) {
+		this();
+		this.name = name;
+	}
+	
+	private String name;
 
 	@OneToMany(mappedBy = "wizard", orphanRemoval = true, cascade = CascadeType.ALL)
 	private Set<Spellbook> spellbooks;
 	
 	public String getFirstName() {
-		return firstName;
+		return name;
 	}
 
 	public void setFirstName(String firstName) {
-		this.firstName = firstName;
+		this.name = firstName;
 	}
 
 	public Set<Spellbook> getSpellbooks() {
@@ -36,4 +41,9 @@ public class Wizard extends BaseEntity {
 	public void setSpellbooks(Set<Spellbook> spellbooks) {
 		this.spellbooks = spellbooks;
 	}
+
+	@Override
+	public String toString() {
+		return name;
+	}	
 }

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

@@ -0,0 +1,5 @@
+package com.iluwatar;
+
+public class WizardDao extends DaoBase<Wizard> {
+
+}