Moving towards Service Layer example.

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

@@ -1,16 +1,15 @@
 package com.iluwatar;
 
-import java.util.List;
 
 
 public class App {
     public static void main( String[] args ) {   
-    	WizardDao dao = new WizardDao();
+    	WizardDaoImpl dao = new WizardDaoImpl();
     	persistData(dao);
-    	queryData(dao);
+    	queryData();
     }
     
-    public static void persistData(WizardDao dao) {
+    public static void persistData(WizardDaoImpl dao) {
     	Spell spell = new Spell("Fireball");
     	Spellbook spellbook = new Spellbook("Book of fire");
     	spell.setSpellbook(spellbook);
@@ -21,16 +20,10 @@ public class App {
     	dao.persist(wizard);
     }
     
-    public static void queryData(WizardDao dao) {
-    	List<Wizard> wizards = dao.findAll();
-    	for (Wizard w: wizards) {
+    public static void queryData() {
+    	MagicService magicService = new MagicServiceImpl();
+    	for (Wizard w: magicService.findAllWizards()) {
     		System.out.println(w);
-    		for (Spellbook spellbook: w.getSpellbooks()) {
-    			System.out.println(spellbook);
-    			for (Spell spell: spellbook.getSpells()) {
-    				System.out.println(spell);
-    			}
-    		}
     	}
     }
 }

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

@@ -0,0 +1,16 @@
+package com.iluwatar;
+
+import java.util.List;
+
+public interface Dao<E extends BaseEntity> {
+
+	E find(Long id);
+	
+	void persist(E entity);
+	
+	E merge(E entity);
+	
+	void delete(E entity);
+	
+	List<E> findAll();
+}

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

@@ -10,7 +10,7 @@ import org.hibernate.Transaction;
 import org.hibernate.cfg.Configuration;
 import org.hibernate.criterion.Restrictions;
 
-public abstract class DaoBase<E extends BaseEntity> {
+public abstract class DaoBaseImpl<E extends BaseEntity> implements Dao<E> {
 	
 	@SuppressWarnings("unchecked")
 	protected Class<E> persistentClass = (Class<E>) ((ParameterizedType) getClass()
@@ -36,7 +36,8 @@ public abstract class DaoBase<E extends BaseEntity> {
 		return sessionFactory.openSession();
 	}
 	
-	E find(Long id) {
+	@Override
+	public E find(Long id) {
 		Session session = getSession();
 		Transaction tx = null;
 		E result = null;
@@ -57,7 +58,8 @@ public abstract class DaoBase<E extends BaseEntity> {
 		return result;
 	}
 	
-	void persist(E entity) {
+	@Override
+	public void persist(E entity) {
 		Session session = getSession();
 		Transaction tx = null;
 		try {
@@ -74,7 +76,8 @@ public abstract class DaoBase<E extends BaseEntity> {
 		}		
 	}
 	
-	E merge(E entity) {
+	@Override
+	public E merge(E entity) {
 		Session session = getSession();
 		Transaction tx = null;
 		E result = null;
@@ -93,7 +96,8 @@ public abstract class DaoBase<E extends BaseEntity> {
 		return result;
 	}
 	
-	void delete(E entity) {
+	@Override
+	public void delete(E entity) {
 		Session session = getSession();
 		Transaction tx = null;
 		try {
@@ -110,7 +114,8 @@ public abstract class DaoBase<E extends BaseEntity> {
 		}		
 	}
 	
-	List<E> findAll() {
+	@Override
+	public List<E> findAll() {
 		Session session = getSession();
 		Transaction tx = null;
 		List<E> result = null;

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

@@ -0,0 +1,13 @@
+package com.iluwatar;
+
+import java.util.List;
+
+public interface MagicService {
+
+	List<Wizard> findAllWizards();
+
+	List<Spellbook> findAllSpellbooks();
+	
+	List<Spell> findAllSpells();
+	
+}

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

@@ -0,0 +1,21 @@
+package com.iluwatar;
+
+import java.util.List;
+
+public class MagicServiceImpl implements MagicService {
+
+	@Override
+	public List<Wizard> findAllWizards() {
+		return new WizardDaoImpl().findAll();
+	}
+
+	@Override
+	public List<Spellbook> findAllSpellbooks() {
+		return new SpellbookDaoImpl().findAll();
+	}
+
+	@Override
+	public List<Spell> findAllSpells() {
+		return new SpellDaoImpl().findAll();
+	}
+}

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

@@ -4,8 +4,6 @@ import javax.persistence.Column;
 import javax.persistence.Entity;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
-import javax.persistence.Inheritance;
-import javax.persistence.InheritanceType;
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
 import javax.persistence.Table;

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

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

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

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

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

@@ -9,8 +9,6 @@ import javax.persistence.Entity;
 import javax.persistence.FetchType;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
-import javax.persistence.Inheritance;
-import javax.persistence.InheritanceType;
 import javax.persistence.JoinColumn;
 import javax.persistence.ManyToOne;
 import javax.persistence.OneToMany;
@@ -48,7 +46,7 @@ public class Spellbook extends BaseEntity {
 	@JoinColumn(name="WIZARD_ID_FK", referencedColumnName="WIZARD_ID")
 	private Wizard wizard;
 
-	@OneToMany(mappedBy = "spellbook", orphanRemoval = true, fetch = FetchType.EAGER, cascade = CascadeType.ALL)
+	@OneToMany(mappedBy = "spellbook", orphanRemoval = true, fetch = FetchType.LAZY, cascade = CascadeType.ALL)
 	private Set<Spell> spells;
 	
 	public String getName() {

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

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

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

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

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

@@ -9,8 +9,6 @@ import javax.persistence.Entity;
 import javax.persistence.FetchType;
 import javax.persistence.GeneratedValue;
 import javax.persistence.Id;
-import javax.persistence.Inheritance;
-import javax.persistence.InheritanceType;
 import javax.persistence.OneToMany;
 import javax.persistence.Table;
 
@@ -42,7 +40,7 @@ public class Wizard extends BaseEntity {
 	
 	private String name;
 
-	@OneToMany(mappedBy = "wizard", orphanRemoval = true, fetch = FetchType.EAGER, cascade = CascadeType.ALL)
+	@OneToMany(mappedBy = "wizard", orphanRemoval = true, fetch = FetchType.LAZY, cascade = CascadeType.ALL)
 	private Set<Spellbook> spellbooks;
 	
 	public String getFirstName() {

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

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

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

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