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About Persistence Context

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Tutorial
261

Step 3: Add a Context Listener Class

of the new source file with the following code: package guest; import javax.persistence.*; import ... = Persistence.createEntityManagerFactory("$objectdb/db/guest.odb"); e.getServletContext ... it as an application scope attribute in the servlet context - when the web application starts
Tutorial
261

Step 3: Add a Context Listener Class

guest; import javax.persistence.*; import javax.servlet.*; public class GuestListener ... .*"); EntityManagerFactory emf = Persistence.createEntityManagerFactory("$objectdb/db ... context - when the web application starts (contextInitialized). Retrieves the EntityManagerFactory
Manual
111

Working with JPA Entity Objects

. The Persistence Context The persistence context is the collection of all the managed objects of an EntityManager. If an entity object that has to be retrieved already exists in the persistence context ... object within the same EntityManager. Every EntityManager manages its own persistence context
Manual
56

JPA Persistence Unit

A JPA Persistence Unit is a logical grouping of user defined persistable classes (entity classes, embeddable classes and mapped superclasses) with related settings. Defining a persistence unit is optional when using ObjectDB, but required by JPA. persistence.xml Persistence units are defined in
Manual
56

Storing JPA Entity Objects

. Therefore, holding 1,000,000 managed Point instances in the persistence context might consume too much memory. The sample code above clears the persistence context after every 10,000 persists. Updates ... New entity objects can be stored in the database either explicitly by invoking the persist method
Tutorial
55

Step 2: Entity Class and Persistence Unit

) and selecting New > Entity Class... (or New > Other... > Persistence > Entity Class and clicking ... the [Provider and Database] step just click Finish to generate a default persistence.xml file with a default persistence unit (that will be configured later). If the Finish button is disabled
Tutorial
55

Step 2: Entity Class and Persistence Unit

) and selecting New > Entity Class... (or New > Other... > Persistence > Entity Class and clicking ... the [Provider and Database] step click Finish to generate a default persistence.xml file with a default persistence unit (that will be configured later). If the Finish button is disabled
Tutorial
54

Step 2: Entity Class and Persistence Unit

.Date; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; @Entity public class Guest implements Serializable { private static final long serialVersionUID = 1L; // Persistent Fields: @Id @GeneratedValue Long id
Tutorial
54

Step 2: Entity Class and Persistence Unit

.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; @Entity ... ; // Persistent Fields: @Id @GeneratedValue Long id; private String name ... guests in the database. We also need to configure JPA by setting a META-INF/persistence.xml file
Manual
51

Entity Management Settings

the persistence context of the EntityManager (which serves as a first level cache). The valid values are "weak ... " />   <persist serialization="false" /> persist always="auto" on-persist="false" on-commit="true" />