GenericRepository.java

package org.opennaas.core.persistence;

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

/**
 * Generic Repository, providing basic CRUD operations
 * 
 * @author Jurgen Lust
 * 
 * @param <T>
 *            the entity type
 * @param <ID>
 *            the primary key type
 */
public interface GenericRepository<T, ID extends Serializable> {
	// ~ Methods ----------------------------------------------------------------

	/**
	 * Get the Class of the entity
	 * 
	 * @return the class
	 */
	Class<T> getEntityClass();

	/**
	 * Find an entity by its primary key
	 * 
	 * @param id
	 *            the primary key
	 * @return the entity
	 */
	T findById(final ID id);

	/**
	 * Load all entities
	 * 
	 * @return the list of entities
	 */
	List<T> findAll();

	/**
	 * Find entities based on an example
	 * 
	 * @param exampleInstance
	 *            the example
	 * @return the list of entities
	 */
	List<T> findByExample(final T exampleInstance);

	/**
	 * Find using a named query
	 * 
	 * @param queryName
	 *            the name of the query
	 * @param params
	 *            the query parameters
	 * 
	 * @return the list of entities
	 */
	List<T> findByNamedQuery(
			final String queryName,
			Object... params
			);

	/**
	 * Find using a named query
	 * 
	 * @param queryName
	 *            the name of the query
	 * @param params
	 *            the query parameters
	 * 
	 * @return the list of entities
	 */
	List<T> findByNamedQueryAndNamedParams(
			final String queryName,
			final Map<String, ? extends Object> params
			);

	/**
	 * Count all entities
	 * 
	 * @return the number of entities
	 */
	int countAll();

	/**
	 * Count entities based on an example
	 * 
	 * @param exampleInstance
	 *            the search criteria
	 * @return the number of entities
	 */
	int countByExample(final T exampleInstance);

	/**
	 * save an entity. This can be either a INSERT or UPDATE in the database
	 * 
	 * @param entity
	 *            the entity to save
	 * 
	 * @return the saved entity
	 */
	T save(final T entity);

	/**
	 * delete an entity from the database
	 * 
	 * @param entity
	 *            the entity to delete
	 */
	void delete(final T entity);
}