org.hibernate.query.Query.stream()方法的使用及代码示例

x33g5p2x  于2022-01-28 转载在 其他  
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本文整理了Java中org.hibernate.query.Query.stream方法的一些代码示例，展示了Query.stream的具体用法。这些代码示例主要来源于Github/Stackoverflow/Maven等平台，是从一些精选项目中提取出来的代码，具有较强的参考意义，能在一定程度帮忙到你。Query.stream方法的具体详情如下：
包路径：org.hibernate.query.Query
类名称：Query
方法名：stream

Query.stream介绍

[英]Retrieve a Stream over the query results.

In the initial implementation (5.2) this returns a simple sequential Stream. The plan is to return a a smarter stream in 6.x leveraging the SQM model.

You should call java.util.stream.Stream#close() after processing the stream so that the underlying resources are deallocated right away.
[中]通过查询结果检索流。
在最初的实现（5.2）中，它返回一个简单的顺序流。计划是在6小时内返回一个更智能的流。x利用SQM模型。
你应该叫java。util。流动流#close（）在处理流后立即释放底层资源。

代码示例

代码示例来源：origin: hibernate/hibernate-orm

  1. /**
  2.    * JPA 2.2 defines the {@code getResultStream} method so to get a {@link Stream} from the JDBC {@link java.sql.ResultSet}.
  3.    *
  4.    * Hibernate 5.2 already defines the {@link Query#stream()} method, so {@code getResultStream} can delegate to it.
  5.    *
  6.    * @return The results Stream
  7.    * @since 5.2.11
  8.    */
  9.   default Stream<R> getResultStream() {
  10.     return stream();
  11.   }
  12. }

代码示例来源：origin: hibernate/hibernate-orm

  1. @Test
  2. public void testSetParameter() throws Exception {
  3.   try (Session session = openSession()) {
  4.     final Query<TestEntity> query = session.createQuery(
  5.         "SELECT e FROM TestEntity e WHERE e.date <= :ts",
  6.         TestEntity.class
  7.     ).setParameter( "ts", new DateAttribute( System.currentTimeMillis() ), TemporalType.TIMESTAMP );
  8.     final Stream<TestEntity> stream = query.stream();
  9.     assertThat( stream.count(), is( 1L ) );
  10.   }
  11. }

代码示例来源：origin: hibernate/hibernate-orm

  1. @Test
  2. public void testStreamMethod() {
  3.   final String entityName = "expected";
  4.   insertTestEntity( entityName );
  5.   try (Session session = openSession()) {
  6.     final CriteriaQuery<TestEntity> query = createTestEntityCriteriaQuery(
  7.         entityName,
  8.         session
  9.     );
  10.     final Stream<TestEntity> stream = session.createQuery( query ).stream();
  11.     assertThat( stream.count(), is( 1L ) );
  12.   }
  13. }

代码示例来源：origin: hibernate/hibernate-orm

  1. Object result = session.createQuery( "From MyEntity" ).stream().findFirst().orElse( null );
  2. assertTyping( MyEntity.class, result );
  3. result = session.createQuery( "From MyEntity", MyEntity.class ).stream().findFirst().orElse( null );
  4. assertTyping( MyEntity.class, result );
  5. session.createQuery( "From MyEntity", MyEntity.class ).stream().forEach( i -> {
  6.   assertTyping( MyEntity.class, i );
  7. } );
  8. Stream<Object[]> data = session.createQuery( "SELECT me.id, me.name FROM MyEntity me" ).stream();
  9. data.forEach( i -> {
  10.   assertTyping( Integer.class, i[0] );

代码示例来源：origin: hibernate/hibernate-orm

  1. @Test
  2. public void test_hql_api_stream_projection_example() {
  3.   doInJPA( this::entityManagerFactory, entityManager -> {
  4.     Session session = entityManager.unwrap( Session.class );
  5.     //tag::hql-api-stream-projection-example[]
  6.     try ( Stream<Object[]> persons = session.createQuery(
  7.       "select p.name, p.nickName " +
  8.       "from Person p " +
  9.       "where p.name like :name" )
  10.     .setParameter( "name", "J%" )
  11.     .stream() ) {
  12.       persons
  13.       .map( row -> new PersonNames(
  14.           (String) row[0],
  15.           (String) row[1] ) )
  16.       .forEach( this::process );
  17.     }
  18.     //end::hql-api-stream-projection-example[]
  19.   });
  20. }

代码示例来源：origin: hibernate/hibernate-orm

  1. @Test
  2. public void test_hql_api_stream_example() {
  3.   doInJPA( this::entityManagerFactory, entityManager -> {
  4.     Session session = entityManager.unwrap( Session.class );
  5.     //tag::hql-api-stream-example[]
  6.     try( Stream<Person> persons = session.createQuery(
  7.       "select p " +
  8.       "from Person p " +
  9.       "where p.name like :name" )
  10.     .setParameter( "name", "J%" )
  11.     .stream() ) {
  12.       Map<Phone, List<Call>> callRegistry = persons
  13.           .flatMap( person -> person.getPhones().stream() )
  14.           .flatMap( phone -> phone.getCalls().stream() )
  15.           .collect( Collectors.groupingBy( Call::getPhone ) );
  16.       process(callRegistry);
  17.     }
  18.     //end::hql-api-stream-example[]
  19.   });
  20. }

代码示例来源：origin: hibernate/hibernate-orm

  1. @Test
  2. @TestForIssue(jiraKey = "HHH-11743")
  3. public void testTupleStream() {
  4.   doInHibernate( this::sessionFactory, session -> {
  5.     MyEntity entity = new MyEntity();
  6.     entity.id = 2;
  7.     entity.name = "an entity";
  8.     session.persist( entity );
  9.   } );
  10.   //test tuple stream using criteria
  11.   doInHibernate( this::sessionFactory, session -> {
  12.     CriteriaBuilder cb = session.getCriteriaBuilder();
  13.     CriteriaQuery<Tuple> criteria = cb.createTupleQuery();
  14.     Root<MyEntity> me = criteria.from( MyEntity.class );
  15.     criteria.multiselect( me.get( "id" ), me.get( "name" ) );
  16.     Stream<Tuple> data = session.createQuery( criteria ).stream();
  17.     data.forEach( tuple -> assertTyping( Tuple.class, tuple ) );
  18.   } );
  19.   //test tuple stream using JPQL
  20.   doInHibernate( this::sessionFactory, session -> {
  21.     Stream<Tuple> data = session.createQuery( "SELECT me.id, me.name FROM MyEntity me", Tuple.class ).stream();
  22.     data.forEach( tuple -> assertTyping( Tuple.class, tuple ) );
  23.   } );
  24. }

代码示例来源：origin: hibernate/hibernate-orm

  1. @Test
  2. public void basicStreamTest() {
  3.   Session session = openSession();
  4.   session.getTransaction().begin();
  5.   // mainly we want to make sure that closing the Stream releases the ScrollableResults too
  6.   assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( false ) );
  7.   final Stream<MyEntity> stream = session.createQuery( "from MyEntity", MyEntity.class ).stream();
  8.   assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( true ) );
  9.   stream.forEach( System.out::println );
  10.   assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( true ) );
  11.   stream.close();
  12.   assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( false ) );
  13.   session.getTransaction().commit();
  14.   session.close();
  15. }

代码示例来源：origin: vladmihalcea/high-performance-java-persistence

  1. private void stream(EntityManager entityManager) {
  2.   final AtomicLong sum = new AtomicLong();
  3.   try(Stream<Post> postStream = entityManager
  4.     .createQuery("select p from Post p", Post.class)
  5.     .setMaxResults(resultSetSize)
  6.     .unwrap(Query.class)
  7.     .stream()) {
  8.     postStream.forEach(post -> sum.incrementAndGet());
  9.   }
  10.   assertEquals(resultSetSize, sum.get());
  11. }

代码示例来源：origin: vladmihalcea/high-performance-java-persistence

  1. private void stream(EntityManager entityManager) {
  2.   final AtomicLong sum = new AtomicLong();
  3.   try(Stream<Post> postStream = entityManager
  4.       .createQuery("select p from Post p", Post.class)
  5.       .setMaxResults(resultSetSize)
  6.       .setHint(QueryHints.HINT_FETCH_SIZE, Integer.MIN_VALUE)
  7.       .unwrap(Query.class)
  8.       .stream()) {
  9.     postStream.forEach(post -> sum.incrementAndGet());
  10.   }
  11.   assertEquals(resultSetSize, sum.get());
  12. }

代码示例来源：origin: vladmihalcea/high-performance-java-persistence

  1. @Test
  2. public void testStreamWithoutMaxResult() {
  3.   List<Post> posts = doInJPA(entityManager -> {
  4.     try(Stream<Post> postStream = entityManager
  5.       .createQuery(
  6.         "select p " +
  7.         "from Post p " +
  8.         "order by p.createdOn desc", Post.class)
  9.       .unwrap(Query.class)
  10.       .stream()
  11.     ) {
  12.       return postStream.limit( 50 ).collect( Collectors.toList() );
  13.     }
  14.   });
  15.   assertEquals(50, posts.size());
  16. }

代码示例来源：origin: org.nuiton.topia/topia-persistence

  1. Query query = prepareQuery(jpaql, parameters);
  2. Stream result = query.stream();
  3. Consumer<T> consumer = row -> {
  4.   List singleton = Collections.singletonList(row);

代码示例来源：origin: vladmihalcea/high-performance-java-persistence

  1. @Test
  2. public void testStream() {
  3.   List<Post> posts = doInJPA(entityManager -> {
  4.     try(Stream<Post> postStream = entityManager
  5.       .createQuery(
  6.         "select p " +
  7.         "from Post p " +
  8.         "order by p.createdOn desc", Post.class)
  9.       .setHint(QueryHints.HINT_FETCH_SIZE, 50)
  10.       .unwrap(Query.class)
  11.       .stream()
  12.     ) {
  13.       return postStream
  14.         .limit(50)
  15.         .collect(Collectors.toList());
  16.     }
  17.   });
  18.   assertEquals(50, posts.size());
  19. }

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