create entity manager programmatically without persistence file

Question

I'm trying to create entity Factory manager programmatically without persistence file

    EntityManagerFactory emf;
    Map<String, String> properties = new HashMap<String, String>();
    properties.put("hibernate.connection.driver_class", "com.mysql.jdbc.Driver");
    properties.put("hibernate.connection.url", "jdbc:mysql://173.194.25***************");
    properties.put("hibernate.connection.username", "etech****");
    properties.put("hibernate.connection.password", "A*****");
    properties.put("hibernate.dialect", "org.hibernate.dialect.MySQLDialect");
    properties.put("hibernate.show-sql", "true");
    properties.put("provider", "org.hibernate.ejb.HibernatePersistence");
    emf = Persistence.createEntityManagerFactory(idClient, properties);

On line

emf = Persistence.createEntityManagerFactory(idClient, properties);

I am getting the error:

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com****RepositoryFieldsFieldWorkerRepositoryImpl': Invocation of init method failed; nested exception is javax.persistence.PersistenceException: No Persistence provider for EntityManager named idClient

How can i resolve this problem ?

any help will be appreciated

Solution 1

Here is a pure programmatic way to build an entity manager without spring and without a persistence.xml. Constants are taken from org.hibernate.cfg.AvailableSettings :

entityManagerFactory = new HibernatePersistenceProvider().createContainerEntityManagerFactory(
            archiverPersistenceUnitInfo(),
            ImmutableMap.<String, Object>builder()
                    .put(JPA_JDBC_DRIVER, JDBC_DRIVER)
                    .put(JPA_JDBC_URL, JDBC_URL)
                    .put(DIALECT, Oracle12cDialect.class)
                    .put(HBM2DDL_AUTO, CREATE)
                    .put(SHOW_SQL, false)
                    .put(QUERY_STARTUP_CHECKING, false)
                    .put(GENERATE_STATISTICS, false)
                    .put(USE_REFLECTION_OPTIMIZER, false)
                    .put(USE_SECOND_LEVEL_CACHE, false)
                    .put(USE_QUERY_CACHE, false)
                    .put(USE_STRUCTURED_CACHE, false)
                    .put(STATEMENT_BATCH_SIZE, 20)
                    .build());

entityManager = entityManagerFactory.createEntityManager();

And the infamous PersistenceUnitInfo

private static PersistenceUnitInfo archiverPersistenceUnitInfo() {
    return new PersistenceUnitInfo() {
        @Override
        public String getPersistenceUnitName() {
            return "ApplicationPersistenceUnit";
        }

        @Override
        public String getPersistenceProviderClassName() {
            return "org.hibernate.jpa.HibernatePersistenceProvider";
        }

        @Override
        public PersistenceUnitTransactionType getTransactionType() {
            return PersistenceUnitTransactionType.RESOURCE_LOCAL;
        }

        @Override
        public DataSource getJtaDataSource() {
            return null;
        }

        @Override
        public DataSource getNonJtaDataSource() {
            return null;
        }

        @Override
        public List<String> getMappingFileNames() {
            return Collections.emptyList();
        }

        @Override
        public List<URL> getJarFileUrls() {
            try {
                return Collections.list(this.getClass()
                                            .getClassLoader()
                                            .getResources(""));
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            }
        }

        @Override
        public URL getPersistenceUnitRootUrl() {
            return null;
        }

        @Override
        public List<String> getManagedClassNames() {
            return Collections.emptyList();
        }

        @Override
        public boolean excludeUnlistedClasses() {
            return false;
        }

        @Override
        public SharedCacheMode getSharedCacheMode() {
            return null;
        }

        @Override
        public ValidationMode getValidationMode() {
            return null;
        }

        @Override
        public Properties getProperties() {
            return new Properties();
        }

        @Override
        public String getPersistenceXMLSchemaVersion() {
            return null;
        }

        @Override
        public ClassLoader getClassLoader() {
            return null;
        }

        @Override
        public void addTransformer(ClassTransformer transformer) {

        }

        @Override
        public ClassLoader getNewTempClassLoader() {
            return null;
        }
    };
}

Note that Spring offers streamlined way to configure the persistence, while supporting multiple hibernate versions. (Spring 4.2 supports Hibernate up to 5.1, Spring 4.3 supports Hibernate up to 5.2).

Solution 2

A persistence.xml file is mandatory to create your persistence unit at deployment time as per the JPA specs.

See Create JPA EntityManager without persistence.xml configuration file