org.josef.jpa

Class AbstractEntity

java.lang.Object

org.josef.jpa.AbstractEntity

All Implemented Interfaces:

Serializable, Persistable

Direct Known Subclasses:

AbstractEntityIdentifiedById, AbstractEntityIdentifiedByObjectId, HtmlTag, Moon, NobelPrizeCategory

@Status(stage=PRODUCTION,
        unitTests=PARTIAL)
 @Review(by="Kees Schotanus",
        at="2009-09-28")
 @MappedSuperclass
public abstract class AbstractEntity
extends Object
implements Persistable, Serializable

Ultimate base class for JPA Entities.
This class defines the version field that is used by JPA providers to support the "Optimistic Locking Strategy". It is assumed that the column in the database table that stores the version, is named "VERSION". To redefine the column name for the version field, add the following annotation to your own JPA Entity:
@AttributeOverride(name = "version", column = @Column(name = "UPDATE_CT"))
This defines that the database column holding the version information is named "UPDATE_CT" in the database table.
Note: This class does not override equals, nor does it override hashCode. The rationale for this decision is given here.

Version:

1.0 $Revision: 6432 $

Author:

Kees Schotanus

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
AbstractEntity() Default constructor as required by JPA specifications.

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object object) Determines whether this AbstractEntity is equal to the supplied object.
Integer	getVersion() Gets the version (number of times this Entity has been updated) of this Entity.
int	hashCode() Computes the hash code of this AbstractEntity.
void	setVersion(Integer version) Sets the version (number of times this Entity has been updated) for this Entity.

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.josef.jpa.Persistable

getPrimaryKey

Constructor Detail

AbstractEntity

public AbstractEntity()

Default constructor as required by JPA specifications.
At least for unenhanced entities.

Method Detail

getVersion

public Integer getVersion()

Gets the version (number of times this Entity has been updated) of this Entity.
The version is used for optimistic locking by the JPA provider.

Specified by:

getVersion in interface Persistable

Returns:

The version of this Entity.
This method returns one for an Entity that has been created, but not updated.

setVersion

public void setVersion(Integer version)

Sets the version (number of times this Entity has been updated) for this Entity.
Used for optimistic locking by the JPA provider.
This method should not be used directly since it could compromise the integrity of this Entity.

Parameters:

version - The version for this Entity.

equals

public boolean equals(Object object)

Determines whether this AbstractEntity is equal to the supplied object.
Both Objects are equal when:

• The supplied Object is an AbstractEntity
• The primary key of both Objects are equal (and non-null)

Overrides:

equals in class Object

Parameters:

object - The Object to compare to.

Returns:

True when both Objects are equal, false otherwise.

hashCode

public int hashCode()

Computes the hash code of this AbstractEntity.
The hash code is 0 when the primary key of this AbstractEntity is null, otherwise it is equal to the hashCode of the primary key.

Overrides:

hashCode in class Object

Returns:

Hash code of this Object.