JPA - createEntityManagerFactory returns Null
Noob question here. I'm following this example/tutorial to try and isolate a problem I keep getting on my main project. Problem is, the entityManagerFactory keeps returning null (thus, I get a NullPointerExcept when trying to run the first JUnit test.)
I'm currently on Eclipse Indigo (JavaEE) - JRE7 - Hibernate 3.6.7 and JBoss 7
And here's my persistence.xml (again, a copipasta taken right from the tutorial)
<persistence>
<persistence-unit name="examplePersistenceUnit"
transaction-type="RESOURCE_LOCAL">
<properties>
<property name="hibernate.show_sql" value="false" />
<prop开发者_如何学编程erty name="hibernate.format_sql" value="false" />
<property name="hibernate.connection.driver_class"
value="org.hsqldb.jdbcDriver" />
<property name="hibernate.connection.url"
value="jdbc:hsqldb:mem:mem:aname" />
<property name="hibernate.connection.username" value="sa" />
<property name="hibernate.dialect"
value="org.hibernate.dialect.HSQLDialect" />
<property name="hibernate.hbm2ddl.auto" value="create" />
</properties>
</persistence-unit>
</persistence>
Things I've already tried/found out so far:
Seems this problem tends to occur if you try to create a factory with a persistence unit that is not listed in the persistence.xml
Double-checked that the necessary JARs are included in Eclipse's Build Path Libraries, which Google suggested may be a possible cause for a createEntityManagerFactory() call to short-circuit and return null (instead of just throwing an exception or logging a message)
Might be due to a possible error whilst configuring Hibernate connection?
I've been hitting this wall for the past couple of weeks, so it goes without saying that any help/general direction tips are MUCH appreciated :D
Gaston, I have some suggestions/questions for you:
1 - Is this the code you're trying to execute?
package entity;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class PersonTest {
private EntityManagerFactory emf;
private EntityManager em;
@Before
public void initEmfAndEm() {
BasicConfigurator.configure();
Logger.getLogger("org").setLevel(Level.ERROR);
emf = Persistence.createEntityManagerFactory("examplePersistenceUnit");
em = emf.createEntityManager();
}
@After
public void cleanup() {
em.close();
}
@Test
public void emptyTest() {
}
}
If it is, try to comment this line: "Logger.getLogger("org").setLevel(Level.ERROR);". Or change it to "Logger.getLogger("org").setLevel(Level.ALL);". Then you should see the errors on the output console.
2 - In your persistence.xml I see you're using hsqldb database. Did you installed/configured it properly?
If you dont't know this database, I suggest you use MySQL, PostgreSQL, or some database you are familiar with.
3 - Check you persistence.xml. Mine is a little bite different:
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0" 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_2_0.xsd">
<persistence-unit name="App1PU" transaction-type="RESOURCE_LOCAL">
<provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
<class>com.entities.User</class>
<class>com.entities.Group</class>
<properties>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql://myIP:3306/mydatabase"/>
<property name="javax.persistence.jdbc.password" value="secret"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.jdbc.Driver"/>
<property name="javax.persistence.jdbc.user" value="myUser"/>
</properties>
</persistence-unit>
</persistence>
Notice the header has some XML declarations that might be important, since Hibernate is telling you that your file is incorrect.
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