No persistence providers available for - jpa-2.0

Question

my file src / main / resources / META-INF / persistence.xml is:
<?xml version="1.0" encoding="UTF-8" ?>
<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"
version="2.0" xmlns="http://java.sun.com/xml/ns/persistence">
<persistence-unit name="todo" transaction-type="RESOURCE_LOCAL">
<class>com.testJPA.classes.Voiture</class>
<properties>
<property name="javax.persistence.jdbc.driver" value="org.hsqldb.jdbcDriver" />
<property name="javax.persistence.jdbc.url" value="jdbc:hsqldb:mem:todos" />
<property name="javax.persistence.jdbc.user" value="sa" />
<property name="javax.persistence.jdbc.password" value="" />
<property name="openjpa.jdbc.SynchronizeMappings" value="buildSchema(ForeignKeys=true)"/>
<property name="openjpa.RuntimeUnenhancedClasses" value="supported"/>
</properties>
</persistence-unit>
my main class is:
package com.testJPA.classes;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;
public class Main {
/**
* #param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
System.out.print("Hello");
EntityManagerFactory emf = Persistence
.createEntityManagerFactory("todo");
EntityManager em = emf.createEntityManager();
for (int i = 0; i < 10; i++) {
Voiture car = new Voiture("a", "b", "c");
em.persist(car);
}
em.getTransaction().commit();
// Find the number of Point objects in the database:
Query q1 = em.createQuery("SELECT COUNT(v) FROM Voiture v");
System.out.println("Le nombre d'enregistrement: "
+ q1.getSingleResult());
}
}
and my clase "Voiture" is :
package com.testJPA.classes;
import javax.persistence.Entity;
import javax.persistence.Id;
#Entity
public class Voiture {
#Id private String matricule;
String position;
String vitesse;
public Voiture(String matricule, String position, String vitesse) {
this.matricule = matricule;
this.position = position;
this.vitesse = vitesse;
}
public Voiture() {
this.matricule = "";
this.position = "";
this.vitesse = "";
}
public String getMatricule() {
return matricule;
}
public void setMatricule(String matricule) {
this.matricule = matricule;
}
public String getPosition() {
return position;
}
public void setPosition(String position) {
this.position = position;
}
public String getVitesse() {
return vitesse;
}
public void setVitesse(String vitesse) {
this.vitesse = vitesse;
}
}
i have this error : No persistence providers available for "todo" after trying the following discovered implementations
sorry i am begineer in JAva EE

Answer 1

This is a classpath issue. You need to have the META-INF directory in the root of your compiled classes directory.
target / classes /
/ com / testJPA / classes / Main.class
/ META-INF / persistence.xml
After you fix this problem, you need to get rid of the openjpa.RuntimeUnenhancedClasses property. That is an evil property that will cause you no end of headaches. Please read this documentation and this documentation on how to properly enhance your Entities.

Answer 2

If JPA is used standalone , you have to specify <provider> in the persistence.xml according to the JPA implementation that you used
For OpenJPA, it is org.apache.openjpa.persistence.PersistenceProviderImpl :
<persistence-unit name="todo" transaction-type="RESOURCE_LOCAL">
<class>com.testJPA.classes.Voiture</class>
<provider>org.apache.openjpa.persistence.PersistenceProviderImpl/provider>
.......................................................
</persistence-unit>