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Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Configuration/JPA/persistence.xml"
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− | =persistence.xml= | + | = persistence.xml = |
− | A persistence unit configures various details that are required when you acquire an entity manager. You specify a persistence unit by name when you acquire an entity manager factory. | + | A persistence unit configures various details that are required when you acquire an entity manager. You specify a persistence unit by name when you acquire an entity manager factory. |
− | You configure persistence units in the JPA persistence descriptor file: '''persistence.xml'''. | + | You configure persistence units in the JPA persistence descriptor file: '''persistence.xml'''. This file should be in the '''meta-inf/''' directory of your persistence unit jar file, or classpath. |
− | In this file, you can specify the vendor extensions that this reference describes by using a ''' | + | In this file, you can specify the vendor extensions that this reference describes by using a '''<properties>''' element. |
+ | <blockquote><source lang="xml"> | ||
+ | <persistence-unit name="default" transaction-type="RESOURCE_LOCAL"> | ||
+ | <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> | ||
− | {{EclipseLink_JPA | + | <!-- By default your mappings can be defined in orm.xml file, --> |
+ | <!-- which is discovered automatically. --> | ||
+ | <mapping-file>META-INF/my-mappings.xml</mapping-file> | ||
+ | ... | ||
+ | <jar-file>my-additional-jar.jar</jar-file> | ||
+ | ... | ||
+ | <!-- Enables auto discovery of persistent classes, --> | ||
+ | <!-- otherwise they must be listed using <class> --> | ||
+ | <exclude-unlisted-classes>false</exclude-unlisted-classes> | ||
+ | |||
+ | <properties> | ||
+ | ... | ||
+ | </properties> | ||
+ | </persistence-unit> | ||
+ | </source> </blockquote> | ||
+ | |||
+ | |||
+ | ==How to Specify the Persistence Unit Name== | ||
+ | |||
+ | If you are developing your application in a Java EE environment, ensure that the persistence unit name is unique within each module. For example, you can define only one persistence unit with the name "EmployeeService" in an emp_ejb.jar file. The following example shows how to define the name of the persistence unit: | ||
+ | |||
+ | <persistence-unit name="EmployeeService"> | ||
+ | |||
+ | For more information, see Section 6.2.1.1 "name" of the JPA Specification. | ||
+ | |||
+ | |||
+ | |||
+ | <br> {{EclipseLink_JPA | ||
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Revision as of 10:51, 15 June 2010
persistence.xml
A persistence unit configures various details that are required when you acquire an entity manager. You specify a persistence unit by name when you acquire an entity manager factory.
You configure persistence units in the JPA persistence descriptor file: persistence.xml. This file should be in the meta-inf/ directory of your persistence unit jar file, or classpath.
In this file, you can specify the vendor extensions that this reference describes by using a <properties> element.
<persistence-unit name="default" transaction-type="RESOURCE_LOCAL"> <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider> <!-- By default your mappings can be defined in orm.xml file, --> <!-- which is discovered automatically. --> <mapping-file>META-INF/my-mappings.xml</mapping-file> ... <jar-file>my-additional-jar.jar</jar-file> ... <!-- Enables auto discovery of persistent classes, --> <!-- otherwise they must be listed using <class> --> <exclude-unlisted-classes>false</exclude-unlisted-classes> <properties> ... </properties> </persistence-unit>
How to Specify the Persistence Unit Name
If you are developing your application in a Java EE environment, ensure that the persistence unit name is unique within each module. For example, you can define only one persistence unit with the name "EmployeeService" in an emp_ejb.jar file. The following example shows how to define the name of the persistence unit:
<persistence-unit name="EmployeeService">
For more information, see Section 6.2.1.1 "name" of the JPA Specification.
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