GenericDao.java

/*******************************************************************************
 *   Gisgraphy Project 
 * 
 *   This library is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU Lesser General Public
 *   License as published by the Free Software Foundation; either
 *   version 2.1 of the License, or (at your option) any later version.
 * 
 *   This library is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 *   Lesser General Public License for more details.
 * 
 *   You should have received a copy of the GNU Lesser General Public
 *   License along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA
 * 
 *  Copyright 2008  Gisgraphy project 
 *  David Masclet <davidmasclet@gisgraphy.com>
 *  
 *  
 *******************************************************************************/
package com.gisgraphy.dao;

import java.io.Serializable;
import java.util.List;

/**
 * Generic DAO (Data Access Object) with common methods to CRUD POJOs.
 * 
 * Extend this interface if you want typesafe (no casting necessary) DAO's for
 * your domain objects.
 * 
 * @author <a href="mailto:bwnoll@gmail.com">Bryan Noll</a>
 * @author <a href="mailto:david.masclet@gisgraphy.com">David Masclet</a>
 * @param <T>
 *                a type variable
 * @param <PK>
 *                the primary key for that type
 */
public interface GenericDao<T, PK extends Serializable> {

    /**
     * Generic method used to get all objects of a particular type. This is the
     * same as lookup up all rows in a table.
     * 
     * @return List of populated objects
     */
    List<T> getAll();

    /**
     * Generic method to get an object based on class and identifier. An
     * ObjectRetrievalFailureException Runtime Exception is thrown if nothing is
     * found.
     * 
     * @param id
     *                the identifier (primary key) of the object to get
     * @return a populated object
     * @see org.springframework.orm.ObjectRetrievalFailureException
     */
    T get(PK id);

    /**
     * Checks for existence of an object of type T using the id arg.
     * 
     * @param id
     *                the id of the entity
     * @return - true if it exists, false if it doesn't
     */
    boolean exists(PK id);

    /**
     * Generic method to save an object - handles both update and insert.
     * 
     * @param object
     *                the object to save
     * @return the persisted object
     */
    T save(T object);

    /**
     * Generic method to delete an object based on class and id
     * 
     * @param id
     *                the identifier (primary key) of the object to remove
     */
    void remove(PK id);
}