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Difference between revisions of "EclipseLink/UserGuide/JPA/Basic JPA Development/Configuration/JPA/persistence.xml"

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m (Replacing page with ' '''Warning See "About the Persistence Unit" in the [http://www.eclipse.org/eclipselink/documentation/ EclipseLink Concepts Guide]'''')
 
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= 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.
 
  
<blockquote><source lang="xml">
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'''[[Image:Elug_draft_icon.png|Warning]] See "About the Persistence Unit" in the [http://www.eclipse.org/eclipselink/documentation/ EclipseLink Concepts Guide]'''
<persistence-unit name="default" transaction-type="RESOURCE_LOCAL">
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  <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
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  <!-- By default your mappings can be defined in orm.xml file, -->
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  <!-- which is discovered automatically.                      -->                                   
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  <mapping-file>META-INF/my-mappings.xml</mapping-file>
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  ...
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  <jar-file>my-additional-jar.jar</jar-file>
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  ...
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  <!-- Enables auto discovery of persistent classes, -->
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  <!-- otherwise they must be listed using <class>  -->
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  <exclude-unlisted-classes>false</exclude-unlisted-classes>
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  <properties>
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    ...
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  </properties>
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</persistence-unit>
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</source> </blockquote>
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==How to Specify the Persistence Unit Name==
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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:
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<persistence-unit name="EmployeeService">
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For more information, see Section 6.2.1.1 "name" of the JPA Specification.
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<br> {{EclipseLink_JPA
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|previous=[[EclipseLink/UserGuide/JPA/Basic_JPA_Development/Configuration/JPA|JPA]]
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|next=[[EclipseLink/UserGuide/JPA/Basic_JPA_Development/Configuration/JPA/Annotations|Annotations]]
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|up=[[EclipseLink/UserGuide/JPA/Basic JPA Development/Configuration|Configuration]]}}
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Latest revision as of 11:47, 25 January 2013


Warning See "About the Persistence Unit" in the EclipseLink Concepts Guide