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

/**
   * JPA 2.2 defines the {@code getResultStream} method so to get a {@link Stream} from the JDBC {@link java.sql.ResultSet}.
   *
   * Hibernate 5.2 already defines the {@link Query#stream()} method, so {@code getResultStream} can delegate to it.
   *
   * @return The results Stream
   * @since 5.2.11
   */
  default Stream<R> getResultStream() {
    return stream();
  }
}

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

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

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

@Test
public void testStreamMethod() {
  final String entityName = "expected";
  insertTestEntity( entityName );
  try (Session session = openSession()) {
    final CriteriaQuery<TestEntity> query = createTestEntityCriteriaQuery(
        entityName,
        session
    );
    final Stream<TestEntity> stream = session.createQuery( query ).stream();
    assertThat( stream.count(), is( 1L ) );
  }
}

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

Object result = session.createQuery( "From MyEntity" ).stream().findFirst().orElse( null );
assertTyping( MyEntity.class, result );
result = session.createQuery( "From MyEntity", MyEntity.class ).stream().findFirst().orElse( null );
assertTyping( MyEntity.class, result );
session.createQuery( "From MyEntity", MyEntity.class ).stream().forEach( i -> {
  assertTyping( MyEntity.class, i );
} );
Stream<Object[]> data = session.createQuery( "SELECT me.id, me.name FROM MyEntity me" ).stream();
data.forEach( i -> {
  assertTyping( Integer.class, i[0] );

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

@Test
public void test_hql_api_stream_projection_example() {
  doInJPA( this::entityManagerFactory, entityManager -> {
    Session session = entityManager.unwrap( Session.class );
    //tag::hql-api-stream-projection-example[]
    try ( Stream<Object[]> persons = session.createQuery(
      "select p.name, p.nickName " +
      "from Person p " +
      "where p.name like :name" )
    .setParameter( "name", "J%" )
    .stream() ) {
      persons
      .map( row -> new PersonNames(
          (String) row[0],
          (String) row[1] ) )
      .forEach( this::process );
    }
    //end::hql-api-stream-projection-example[]
  });
}

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

@Test
public void test_hql_api_stream_example() {
  doInJPA( this::entityManagerFactory, entityManager -> {
    Session session = entityManager.unwrap( Session.class );
    //tag::hql-api-stream-example[]
    try( Stream<Person> persons = session.createQuery(
      "select p " +
      "from Person p " +
      "where p.name like :name" )
    .setParameter( "name", "J%" )
    .stream() ) {
      Map<Phone, List<Call>> callRegistry = persons
          .flatMap( person -> person.getPhones().stream() )
          .flatMap( phone -> phone.getCalls().stream() )
          .collect( Collectors.groupingBy( Call::getPhone ) );
      process(callRegistry);
    }
    //end::hql-api-stream-example[]
  });
}

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

@Test
@TestForIssue(jiraKey = "HHH-11743")
public void testTupleStream() {
  doInHibernate( this::sessionFactory, session -> {
    MyEntity entity = new MyEntity();
    entity.id = 2;
    entity.name = "an entity";
    session.persist( entity );
  } );
  //test tuple stream using criteria
  doInHibernate( this::sessionFactory, session -> {
    CriteriaBuilder cb = session.getCriteriaBuilder();
    CriteriaQuery<Tuple> criteria = cb.createTupleQuery();
    Root<MyEntity> me = criteria.from( MyEntity.class );
    criteria.multiselect( me.get( "id" ), me.get( "name" ) );
    Stream<Tuple> data = session.createQuery( criteria ).stream();
    data.forEach( tuple -> assertTyping( Tuple.class, tuple ) );
  } );
  //test tuple stream using JPQL
  doInHibernate( this::sessionFactory, session -> {
    Stream<Tuple> data = session.createQuery( "SELECT me.id, me.name FROM MyEntity me", Tuple.class ).stream();
    data.forEach( tuple -> assertTyping( Tuple.class, tuple ) );
  } );
}

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

@Test
public void basicStreamTest() {
  Session session = openSession();
  session.getTransaction().begin();
  // mainly we want to make sure that closing the Stream releases the ScrollableResults too
  assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( false ) );
  final Stream<MyEntity> stream = session.createQuery( "from MyEntity", MyEntity.class ).stream();
  assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( true ) );
  stream.forEach( System.out::println );
  assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( true ) );
  stream.close();
  assertThat( ( (SessionImplementor) session ).getJdbcCoordinator().getLogicalConnection().getResourceRegistry().hasRegisteredResources(), is( false ) );
  session.getTransaction().commit();
  session.close();
}

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

private void stream(EntityManager entityManager) {
  final AtomicLong sum = new AtomicLong();
  try(Stream<Post> postStream = entityManager
    .createQuery("select p from Post p", Post.class)
    .setMaxResults(resultSetSize)
    .unwrap(Query.class)
    .stream()) {
    postStream.forEach(post -> sum.incrementAndGet());
  }
  assertEquals(resultSetSize, sum.get());
}

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

private void stream(EntityManager entityManager) {
  final AtomicLong sum = new AtomicLong();
  try(Stream<Post> postStream = entityManager
      .createQuery("select p from Post p", Post.class)
      .setMaxResults(resultSetSize)
      .setHint(QueryHints.HINT_FETCH_SIZE, Integer.MIN_VALUE)
      .unwrap(Query.class)
      .stream()) {
    postStream.forEach(post -> sum.incrementAndGet());
  }
  assertEquals(resultSetSize, sum.get());
}

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

@Test
public void testStreamWithoutMaxResult() {
  List<Post> posts = doInJPA(entityManager -> {
    try(Stream<Post> postStream = entityManager
      .createQuery(
        "select p " +
        "from Post p " +
        "order by p.createdOn desc", Post.class)
      .unwrap(Query.class)
      .stream()
    ) {
      return postStream.limit( 50 ).collect( Collectors.toList() );
    }
  });
  assertEquals(50, posts.size());
}

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

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

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

@Test
public void testStream() {
  List<Post> posts = doInJPA(entityManager -> {
    try(Stream<Post> postStream = entityManager
      .createQuery(
        "select p " +
        "from Post p " +
        "order by p.createdOn desc", Post.class)
      .setHint(QueryHints.HINT_FETCH_SIZE, 50)
      .unwrap(Query.class)
      .stream()
    ) {
      return postStream
        .limit(50)
        .collect(Collectors.toList());
    }
  });
  assertEquals(50, posts.size());
}

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