1 /*

     2  * Copyright (c) 2007-2008 Nokia Corporation and/or its subsidiary(-ies).

     3  * All rights reserved.

     4  * This component and the accompanying materials are made available

     5  * under the terms of the License "Eclipse Public License v1.0"

     6  * which accompanies this distribution, and is available

     7  * at the URL "http://www.eclipse.org/legal/epl-v10.html".

     8  *

     9  * Initial Contributors:

    10  * Nokia Corporation - initial contribution.

    11  *

    12  * Contributors:

    13  *

    14  * Description:  

    15  *

    16  */

    17 package com.nokia.helium.metadata;

    18 

    19 import java.io.Serializable;

    20 import java.lang.reflect.ParameterizedType;

    21 import java.util.List;

    22 

    23 import javax.persistence.EntityManager;

    24 import javax.persistence.PersistenceContext;

    25 

    26 /**

    27  * Abstract class which implement the DAO pattern for the JPA

    28  * API. 

    29  *

    30  * @param <T> implementing the DAO for T.

    31  */

    32 public abstract class JpaDAO<T> implements DAO<T> {

    33     

    34     private Class<T> entityBeanType;

    35    

    36     @PersistenceContext

    37     private EntityManager entityManager;

    38 

    39     /**

    40      * Default constructor. Does some basic internal configuration.

    41      */

    42     @SuppressWarnings("unchecked")

    43     public JpaDAO() {

    44         this.entityBeanType = (Class<T>) ((ParameterizedType) getClass()

    45                 .getGenericSuperclass()).getActualTypeArguments()[0];

    46     }

    47     

    48     /**

    49      * @param entityManager the entityManager to set

    50      */

    51     public void setEntityManager(EntityManager entityManager) {

    52         this.entityManager = entityManager;

    53     }

    54 

    55     /**

    56      * @return the entityManager

    57      */

    58     protected EntityManager getEntityManager() {

    59         return entityManager;

    60     }

    61     

    62     /**

    63      * {@inheritDoc}

    64      */

    65     public T findById(Serializable id) {

    66         return entityManager.find(getEntityBeanType(), id);

    67     }

    68    

    69     /**

    70      * {@inheritDoc}

    71      */

    72     public List<T> findAll() {

    73         return entityManager.createQuery("from " +

    74                 getEntityBeanType().getName(), getEntityBeanType()).getResultList();

    75     }

    76    

    77     /**

    78      * Get the class this object is implementing the DAO for.  

    79      * @return the class this object is implementing the DAO for.

    80      */

    81     protected Class<T> getEntityBeanType() {

    82         return entityBeanType;

    83     }

    84     

    85     /**

    86      * {@inheritDoc}

    87      */

    88     public void persist(T data) {

    89         entityManager.persist(data);

    90     }

    91 

    92     /**

    93      * {@inheritDoc}

    94      */

    95     public void remove(T data) {

    96         entityManager.remove(data);

    97     }

    98    

    99 }

   100