net.craftforge.essential.example.persistence
Class CrudDao<T>

java.lang.Object
  net.craftforge.essential.example.persistence.CrudDao<T>

Type Parameters:

T - The entity type

public class CrudDao<T>
extends Object

A CRUD DAO generalizes the simple create, read, update and delete methods for entities of a given type. Each operations opens, commits and closes transactions itself.

Do not use this DAO for a sequence of operations if they shall share one transaction.

Since:

09.08.11

Author:

Christian Bick

Constructor Summary

CrudDao(javax.persistence.EntityManager entityManager)
Initializes the CRUD DAO with the entity manager to use for its operations.

Method Summary

T	createEntity(T entity) Creates an entity by making it persistent.
void	deleteEntity(Class<T> clazz, Integer id) Deletes an entity of the given class with the specified id by removing it from the persistence context.
T	readEntity(Class<T> clazz, Integer id) Reads an entity of the given class with the specified id by finding it in the the persistence context.
protected void	requireExistence(T entity) Requires the existence of an entity.
T	updateEntity(Integer id, T entity) Updates an entity by merging it into the persistence context.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CrudDao

public CrudDao(javax.persistence.EntityManager entityManager)

Initializes the CRUD DAO with the entity manager to use for its operations.

Parameters:

entityManager - The entity manager

Method Detail

createEntity

public T createEntity(T entity)
               throws net.craftforge.essential.controller.ControllerException

Creates an entity by making it persistent.

Parameters:

entity - The entity to persist

Returns:

The now persistent entity

Throws:

net.craftforge.essential.controller.ControllerException - if the entity has already been persistent

updateEntity

public T updateEntity(Integer id,
                      T entity)
               throws net.craftforge.essential.controller.ControllerException

Updates an entity by merging it into the persistence context.

Parameters:

id - The entity id

entity - The entity to merge

Returns:

The merged entity

Throws:

net.craftforge.essential.controller.ControllerException - if no entity with the given id has already been persistent

deleteEntity

public void deleteEntity(Class<T> clazz,
                         Integer id)
                  throws net.craftforge.essential.controller.ControllerException

Deletes an entity of the given class with the specified id by removing it from the persistence context.

Parameters:

clazz - The entity class

id - The entity id

Throws:

net.craftforge.essential.controller.ControllerException - if no entity with the given id has already been persistent

readEntity

public T readEntity(Class<T> clazz,
                    Integer id)
             throws net.craftforge.essential.controller.ControllerException

Reads an entity of the given class with the specified id by finding it in the the persistence context.

Parameters:

clazz - The entity class

id - The entity id

Returns:

The found entity

Throws:

net.craftforge.essential.controller.ControllerException - if no entity with the given id has already been persistent

requireExistence

protected void requireExistence(T entity)
                         throws net.craftforge.essential.controller.ControllerException

Requires the existence of an entity.

Parameters:

entity - The entity

Throws:

net.craftforge.essential.controller.ControllerException - if the entity is null