JPAConnection.java 文件源码

public JPAConnection() {
    if (entityManager == null) {
        EntityManagerFactory emf;
        if (DB.equals(DERBY)) {
            emf = Persistence.createEntityManagerFactory(DERBY);
        } else {
            Map<String, String> propertyMap = new HashMap<>();
            propertyMap.put(CassandraConstants.CQL_VERSION, CassandraConstants.CQL_VERSION_3_0);
            emf = Persistence.createEntityManagerFactory(CASSANDRA, propertyMap);
        }
        entityManager = emf.createEntityManager();
    }
}