openJPA on Java SE

问题

I try to develop JPA project on ibm RAD. And i can run it on Webpshere successfully, but the problem is my machine is quite old. So deploying in Java EE container isn't reasonable.And i want to run it on JSE.But it gives following error:

94  test  INFO   [main] openjpa.Runtime - Starting OpenJPA 1.2.1-SNAPSHOT
235  test  INFO   [main] openjpa.jdbc.JDBC - Using dictionary class "com.ibm.ws.persistence.jdbc.sql.DB2Dictionary".
1797  test  WARN   [main] openjpa.Enhance - This configuration disallows runtime optimization, but the following listed types were not enhanced at build time or at class load time with a javaagent: "[class Customer]".
Exception in thread "main" <openjpa-1.2.1-SNAPSHOT-r422266:686069 fatal user error> org.apache.openjpa.persistence.ArgumentException: The type "class Customer" has not been enhanced.
    at org.apache.openjpa.meta.ClassMetaData.resolveMeta(ClassMetaData.java:1650)
    at org.apache.openjpa.meta.ClassMetaData.resolve(ClassMetaData.java:1624)
    at org.apache.openjpa.meta.MetaDataRepository.processBuffer(MetaDataRepository.java:717)
    at org.apache.openjpa.meta.MetaDataRepository.resolveMeta(MetaDataRepository.java:616)
    at org.apache.openjpa.meta.MetaDataRepository.resolve(MetaDataRepository.java:541)
    at org.apache.openjpa.meta.MetaDataRepository.getMetaData(MetaDataRepository.java:308)
    at org.apache.openjpa.kernel.BrokerImpl.newObjectId(BrokerImpl.java:1114)
    at org.apache.openjpa.kernel.DelegatingBroker.newObjectId(DelegatingBroker.java:268)
    at org.apache.openjpa.persistence.EntityManagerImpl.find(EntityManagerImpl.java:451)
    at deneme.main(deneme.java:21)

What i'm missing?

By the my persistent.xml is:

**<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
    <persistence-unit name="test" transaction-type="RESOURCE_LOCAL">
    <provider>
        com.ibm.websphere.persistence.PersistenceProviderImpl
    </provider> 
        <class>Customer</class>
        <properties>
            <property name="openjpa.ConnectionDriverName" value="com.ibm.db2.jcc.DB2Driver"/>
            <property name="openjpa.ConnectionURL" value="jdbc:db2://localhost:50000/PARUD:retrieveMessagesFromServerOnGetMessage=true;"/>
            <property name="openjpa.ConnectionUserName" value="db2admin"/>
            <property name="openjpa.ConnectionPassword" value="xxxxx"/>
            <property name="openjpa.jdbc.Schema" value="POOL"/>
        </properties>
    </persistence-unit>
</persistence>**

回答1:

Just a pointer: You need to enhance your classes e.g. at runtime via -javaagent:yourlib.jar or even while compiling. You could learn more on this topic here:

"The second and recommended way get runtime enhancement is to provide a javaagent when launching the JVM that OpenJPA is going run in."

回答2:

I just went through the exercise of getting OpenJPA 2.1.0 to run on Tomcat 7.0. I was simply unable to get run-time enhancement to work under Tomcat so I gave up and decided to use build-time enhancement. I am developing my code under Eclipse so I followed the instructions here:

http://openjpa.apache.org/enhancement-with-eclipse.html

Note however that the instructions on this page are for generic java projects. If you are working with Dynamic Web Projects, be sure to specify the build directory argument correctly. I used -Dbuild.dir=build/classes which is the typical location for the compiled code.

One more annoying quirk you have to live with. You must manually invoke the builder using the "Project > Build Project" menu item. When the enhancer runs, it modifies the previously built classes. Consequently, you need to hit F5 or Refresh for the project before you publish to Tomcat.

来源：https://stackoverflow.com/questions/2127263/openjpa-on-java-se