@PersistenceContext(unitName = "JPAUNIT", type = PersistenceContextType.EXTENDED)
private EntityManager em;

public boolean saveUsr(User user){
    em.getTransaction().begin();
    try {
        em.persist(user);
        em.getTransaction().commit();
        return true;
    }catch (Exception e){
        System.out.println("User exists");
        return false;
    }
}

<persistence-unit name="JPAUNIT">
                <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

    <class>classes</class>

    <properties>
        <property name="hibernate.connection.url" value="jdbc:postgresql://localhost:5432/points"/>
        <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
        <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQL9Dialect"/>
        <property name="hibernate.connection.username" value="postgres"/>
        <property name="hibernate.connection.password" value="1234"/>
    </properties>

</persistence-unit>

<dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.3.7.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate.javax.persistence</groupId>
        <artifactId>hibernate-jpa-2.1-api</artifactId>
        <version>1.0.0.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>5.3.7.Final</version>
    </dependency>