Java Reference
In-Depth Information
In the
Summary
Page
click on
Finish
. The entity bean class
model.Catalog
gets
created. The
persistence.xml
deployment descriptor gets created in the
META-INF
directory.
The Entity class
The entity bean class is just a POJO class annotated with the
@Entity
annotation. A
@NamedQuery
specifies a
findAll
query, which selects all the entity instances. An
entity bean, which is persisted to a database and has caching enabled, is serialized
by caches. Therefore, the entity bean class implements the
java.io.Serializable
interface. Specify a
serialVersionUID
variable, which is used by serialization
runtime to associate a version number with the serializable class:
private static final long serialVersionUID = 7422574264557894633L;
The database columns are mapped to entity bean properties, which are defined as
private
variables. The getter setter methods for the properties are also defined. The
identifier property is specified with the
@Id
annotation. The
@Column
annotation
specifies that the
id
column is not nullable:
@Id
@Column(nullable = false)
private long id;
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