我在我的应用程序中使用hibernate jpa,它可以自动创建表但不能删除它,我已经将“hibernate.hbm2ddl.auto”设置为“create-drop”。这是我的设置:
<persistence-unit name="jobs-postgres">
<properties>
<property name="javax.persistence.jdbc.driver" value="org.postgresql.Driver" />
<property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect" />
<property name="hibernate.connection.provider_class" value="org.hibernate.connection.C3P0ConnectionProvider" />
<property name="hibernate.hbm2ddl.auto" value="create-drop" />
<!-- Connection provider properties. -->
<property name="hibernate.c3p0.max_size" value="100" />
<property name="hibernate.c3p0.min_size" value="1" />
<property name="hibernate.c3p0.acquire_increment" value="1" />
<property name="hibernate.c3p0.idle_test_period" value="60" />
<property name="hibernate.c3p0.max_statements" value="0" />
<property name="hibernate.c3p0.timeout" value="30" />
<!-- Miscellaneous Hibernate properties. -->
<property name="hibernate.max_fetch_depth" value="3" />
<property name="hibernate.cache.use_query_cache" value="false" />
<property name="hibernate.cache.use_second_level_cache" value="false" />
<property name="hibernate.search.autoregister_listeners" value="false" />
<property name="hibernate.jdbc.batch_size" value="1000"/>
<property name="hibernate.generate_statistics" value="false" />
<property name="hibernate.show_sql" value="false" />
</properties>
</persistence-unit>
存储库.java
public class JPATagsRepository {
private static final Logger LOGGER = LoggerFactory.getLogger(JPATagsRepository.class);
private final EntityManagerFactory _emf;
public JPATagsRepository(EntityManagerFactory emf) {
if (emf == null) {
throw new IllegalArgumentException("Entity manager cannot be null.");
}
this._emf = emf;
}
public void store(Set<String> tagStr, int type) {
if (tagStr.size() == 0) {
throw new IllegalArgumentException("Tags are empty.");
}
EntityManager em = null;
EntityTransaction tx = null;
try {
em = _emf.createEntityManager();
tx = em.getTransaction();
tx.begin();
int i = 0;
for (String s : tagStr) {
Tag tag = new Tag(s, type);
if (getByName(tag.getName()) == null) {
em.persist(tag);
}
if (++i % 1000 == 0) {
em.flush();
em.clear();
}
}
tx.commit();
}
finally {
if (tx != null && tx.isActive()) {
tx.rollback();
}
if (em != null) {
em.close();
em = null;
}
}
}
}
应用程序.java
Properties config = new Properties();
FileInputStream in = new FileInputStream(DEFAULT_OP_CONFIG_LOCATION);
config.load(in);
in.close();
Map<String, String> properties = Maps.newHashMap();
properties.put("javax.persistence.jdbc.url", config.getProperty("db_url"));
properties.put("javax.persistence.jdbc.user", config.getProperty("db_user"));
properties.put("javax.persistence.jdbc.password", config.getProperty("db_password"));
EntityManagerFactory emf = Persistence.createEntityManagerFactory("jobs-postgres", properties);
JPATagsRepository tagRepository = new JPATagsRepository(emf);