java.util.stream.StreamSupport#stream ( )源码实例Demo

private void processDeletion(ResourceChange change) {
    String path = change.getPath();
    LOG.debug("Process resource deletion at path {}", path);

    Resource parent = resolver.getResource(BINDINGS_PARENT_PATH);
    Iterator<Resource> resourceIterator = parent.listChildren();

    Stream<Resource> targetStream = StreamSupport.stream(Spliterators.spliteratorUnknownSize(resourceIterator, Spliterator.ORDERED),
        false);

    targetStream.filter(res -> {
        ValueMap properties = res.getValueMap();
        LOG.debug("Checking the binding at {}", res.getPath());
        String cqConf = properties.get(Constants.PN_CONF, "");
        if (StringUtils.isEmpty(cqConf)) {
            return false;
        }
        return path.equals(cqConf + "/" + Constants.COMMERCE_BUCKET_PATH);
    }).findFirst().ifPresent(res -> {
        LOG.debug("Found a binding at {} that uses {}, we'll delete it", res.getPath(), path);
        deleteJcrNode(res);
    });
}
 

/**
 * @hide
 */
public static Stream<SliceItem> stream(SliceItem slice) {
    Queue<SliceItem> items = new LinkedList();
    items.add(slice);
    Iterator<SliceItem> iterator = new Iterator<SliceItem>() {
        @Override
        public boolean hasNext() {
            return items.size() != 0;
        }

        @Override
        public SliceItem next() {
            SliceItem item = items.poll();
            if (compareTypes(item, SliceItem.FORMAT_SLICE)
                    || compareTypes(item, SliceItem.FORMAT_ACTION)) {
                items.addAll(item.getSlice().getItems());
            }
            return item;
        }
    };
    return StreamSupport.stream(Spliterators.spliteratorUnknownSize(iterator, 0), false);
}
 

/**
 * @return a {@link Stream} that lazily binds to this {@link Spliterator} when evaluated.
 */
public Stream<T> stream() {
    return StreamSupport.stream(
        () -> this,
        Spliterator.ORDERED | Spliterator.IMMUTABLE | Spliterator.NONNULL,
        false
    );
}
 

@Override
public <A extends Annotation> Stream<MergedAnnotation<A>> stream(Class<A> annotationType) {
	if (this.annotationFilter == FILTER_ALL) {
		return Stream.empty();
	}
	return StreamSupport.stream(spliterator(annotationType), false);
}
 

@SuppressWarnings("unchecked")
@Override
public <N> Stream<K> getKeys(String state, N namespace) {
	RocksDbKvStateInfo columnInfo = kvStateInformation.get(state);
	if (columnInfo == null || !(columnInfo.metaInfo instanceof RegisteredKeyValueStateBackendMetaInfo)) {
		return Stream.empty();
	}

	RegisteredKeyValueStateBackendMetaInfo<N, ?> registeredKeyValueStateBackendMetaInfo =
		(RegisteredKeyValueStateBackendMetaInfo<N, ?>) columnInfo.metaInfo;

	final TypeSerializer<N> namespaceSerializer = registeredKeyValueStateBackendMetaInfo.getNamespaceSerializer();
	final DataOutputSerializer namespaceOutputView = new DataOutputSerializer(8);
	boolean ambiguousKeyPossible = RocksDBKeySerializationUtils.isAmbiguousKeyPossible(getKeySerializer(), namespaceSerializer);
	final byte[] nameSpaceBytes;
	try {
		RocksDBKeySerializationUtils.writeNameSpace(
			namespace,
			namespaceSerializer,
			namespaceOutputView,
			ambiguousKeyPossible);
		nameSpaceBytes = namespaceOutputView.getCopyOfBuffer();
	} catch (IOException ex) {
		throw new FlinkRuntimeException("Failed to get keys from RocksDB state backend.", ex);
	}

	RocksIteratorWrapper iterator = RocksDBOperationUtils.getRocksIterator(db, columnInfo.columnFamilyHandle);
	iterator.seekToFirst();

	final RocksStateKeysIterator<K> iteratorWrapper = new RocksStateKeysIterator<>(iterator, state, getKeySerializer(), keyGroupPrefixBytes,
		ambiguousKeyPossible, nameSpaceBytes);

	Stream<K> targetStream = StreamSupport.stream(Spliterators.spliteratorUnknownSize(iteratorWrapper, Spliterator.ORDERED), false);
	return targetStream.onClose(iteratorWrapper::close);
}
 

@Override
public Stream<VideoMetadata> streamVideoMetadata(VideoQuery query) {
	Preconditions.checkNotNull(query.getPlaceId(), "Must specify placeid");
	
	UUID start = start(query);
	UUID end = end(query);
	
	logger.debug("Querying recordings by: types: {} deleted: {} tags: {} cameras: {} in range [{} - {}] limit [{}]", query.getRecordingType(), query.isListDeleted(), query.getTags(), query.getCameras(), start, end, query.getLimit());
	Predicate<VideoMetadata> predicate = queryPredicate(query);
	Iterator<VideoRecordingSize> recordingIds = queryPlan(query, start, end);
	Iterator<VideoMetadata> result = Iterators.transform(recordingIds, (r) -> fetchVideoMetadata(r, predicate));
     Spliterator<VideoMetadata> stream = Spliterators.spliteratorUnknownSize(result, Spliterator.IMMUTABLE | Spliterator.NONNULL);
     return StreamSupport.stream(stream, false);
	
}
 

@SuppressWarnings("unchecked")
@Override
public <N> Stream<K> getKeys(String state, N namespace) {
	RocksDbKvStateInfo columnInfo = kvStateInformation.get(state);
	if (columnInfo == null || !(columnInfo.metaInfo instanceof RegisteredKeyValueStateBackendMetaInfo)) {
		return Stream.empty();
	}

	RegisteredKeyValueStateBackendMetaInfo<N, ?> registeredKeyValueStateBackendMetaInfo =
		(RegisteredKeyValueStateBackendMetaInfo<N, ?>) columnInfo.metaInfo;

	final TypeSerializer<N> namespaceSerializer = registeredKeyValueStateBackendMetaInfo.getNamespaceSerializer();
	final DataOutputSerializer namespaceOutputView = new DataOutputSerializer(8);
	boolean ambiguousKeyPossible = RocksDBKeySerializationUtils.isAmbiguousKeyPossible(getKeySerializer(), namespaceSerializer);
	final byte[] nameSpaceBytes;
	try {
		RocksDBKeySerializationUtils.writeNameSpace(
			namespace,
			namespaceSerializer,
			namespaceOutputView,
			ambiguousKeyPossible);
		nameSpaceBytes = namespaceOutputView.getCopyOfBuffer();
	} catch (IOException ex) {
		throw new FlinkRuntimeException("Failed to get keys from RocksDB state backend.", ex);
	}

	RocksIteratorWrapper iterator = RocksDBOperationUtils.getRocksIterator(db, columnInfo.columnFamilyHandle);
	iterator.seekToFirst();

	final RocksStateKeysIterator<K> iteratorWrapper = new RocksStateKeysIterator<>(iterator, state, getKeySerializer(), keyGroupPrefixBytes,
		ambiguousKeyPossible, nameSpaceBytes);

	Stream<K> targetStream = StreamSupport.stream(Spliterators.spliteratorUnknownSize(iteratorWrapper, Spliterator.ORDERED), false);
	return targetStream.onClose(iteratorWrapper::close);
}
 

@NonNull
@Override
public <T> Stream<T> entityStream(@NonNull ResultSet resultSet, @Nullable String prefix, @NonNull Class<T> rootEntity) {
    ArgumentUtils.requireNonNull("resultSet", resultSet);
    ArgumentUtils.requireNonNull("rootEntity", rootEntity);
    TypeMapper<ResultSet, T> mapper = new SqlResultEntityTypeMapper<>(prefix, getEntity(rootEntity), columnNameResultSetReader, jsonCodec);
    Iterable<T> iterable = () -> new Iterator<T>() {
        boolean nextCalled = false;

        @Override
        public boolean hasNext() {
            try {
                if (!nextCalled) {
                    nextCalled = true;
                    return resultSet.next();
                } else {
                    return nextCalled;
                }
            } catch (SQLException e) {
                throw new DataAccessException("Error retrieving next JDBC result: " + e.getMessage(), e);
            }
        }

        @Override
        public T next() {
            nextCalled = false;
            return mapper.map(resultSet, rootEntity);
        }
    };
    return StreamSupport.stream(iterable.spliterator(), false);
}
 

@Override
public Stream<Place> streamAll() {
   Context timer = streamAllTimer.time();
   Iterator<Row> rows = session.execute(streamAll.bind()).iterator();
   Iterator<Place> result = TimingIterator.time(
         Iterators.transform(rows, (row) -> buildEntity(row)),
         timer
   );
   Spliterator<Place> stream = Spliterators.spliteratorUnknownSize(result, Spliterator.IMMUTABLE | Spliterator.NONNULL);
   return StreamSupport.stream(stream, false);
}
 

public static <T> Stream<T> enumerationAsStream(final Enumeration<T> e) {
    return StreamSupport.stream(Spliterators.spliteratorUnknownSize(new Iterator<T>() {
        public T next() {
            return e.nextElement();
        }

        public boolean hasNext() {
            return e.hasMoreElements();
        }
    }, Spliterator.ORDERED), false);
}
 

@Override
public Stream<Person> streamAll() {
   try(Context ctxt = streamAllTimer.time()) {
      Iterator<Row> rows = session.execute(new BoundStatement(findAllPeople)).iterator();
      Iterator<Person> result = Iterators.transform(rows, (row) -> buildEntity(row));
      Spliterator<Person> stream = Spliterators.spliteratorUnknownSize(result, Spliterator.IMMUTABLE | Spliterator.NONNULL);
      return StreamSupport.stream(stream, false);
   }
}
 

/**
 * Returns a {@code Stream}, the elements of which are lines read from
 * this {@code BufferedReader}.  The {@link Stream} is lazily populated,
 * i.e., read only occurs during the
 * <a href="../util/stream/package-summary.html#StreamOps">terminal
 * stream operation</a>.
 *
 * <p> The reader must not be operated on during the execution of the
 * terminal stream operation. Otherwise, the result of the terminal stream
 * operation is undefined.
 *
 * <p> After execution of the terminal stream operation there are no
 * guarantees that the reader will be at a specific position from which to
 * read the next character or line.
 *
 * <p> If an {@link IOException} is thrown when accessing the underlying
 * {@code BufferedReader}, it is wrapped in an {@link
 * UncheckedIOException} which will be thrown from the {@code Stream}
 * method that caused the read to take place. This method will return a
 * Stream if invoked on a BufferedReader that is closed. Any operation on
 * that stream that requires reading from the BufferedReader after it is
 * closed, will cause an UncheckedIOException to be thrown.
 *
 * @return a {@code Stream<String>} providing the lines of text
 *         described by this {@code BufferedReader}
 *
 * @since 1.8
 */
public Stream<String> lines() {
    Iterator<String> iter = new Iterator<String>() {
        String nextLine = null;

        @Override
        public boolean hasNext() {
            if (nextLine != null) {
                return true;
            } else {
                try {
                    nextLine = readLine();
                    return (nextLine != null);
                } catch (IOException e) {
                    throw new UncheckedIOException(e);
                }
            }
        }

        @Override
        public String next() {
            if (nextLine != null || hasNext()) {
                String line = nextLine;
                nextLine = null;
                return line;
            } else {
                throw new NoSuchElementException();
            }
        }
    };
    return StreamSupport.stream(Spliterators.spliteratorUnknownSize(
            iter, Spliterator.ORDERED | Spliterator.NONNULL), false);
}
 

@Override
public List<CandidateSnapshot> findCandidates(String group) {
    Stream<CandidateSnapshot> candidates = StreamSupport.stream(Iterables.concat(
            configDao.findCurrentSnapshotsInGroup(group), referenceDao.findCurrentSnapshotsInGroup(group)).spliterator(), false);
    return candidates.collect(Collectors.toList());
}
 

private Stream<CSVRecord> readCsvFile(Reader reader, String... header) throws IOException
{
    return StreamSupport.stream(csvFormat.withHeader(header).parse(reader).spliterator(), false);
}
 

@Override
public <A extends Annotation> Stream<MergedAnnotation<A>> stream(Class<A> annotationType) {
	return StreamSupport.stream(spliterator(annotationType), false);
}
 

@Override
public Stream<MergedAnnotation<Annotation>> stream() {
	return StreamSupport.stream(spliterator(), false);
}
 

default Stream<T> stream() {
	return StreamSupport.stream(spliterator(), false);
}
 

public static <T> Stream<T> toStream(Iterator<T> it) {
    return StreamSupport.stream(toIterable(it).spliterator(), false);
}
 

/**
 * Returns a sequential {@code Stream} with this collection as its source.
 *
 * <p>This method should be overridden when the {@link #spliterator()}
 * method cannot return a spliterator that is {@code IMMUTABLE},
 * {@code CONCURRENT}, or <em>late-binding</em>. (See {@link #spliterator()}
 * for details.)
 *
 * @implSpec
 * The default implementation creates a sequential {@code Stream} from the
 * collection's {@code Spliterator}.
 *
 * @return a sequential {@code Stream} over the elements in this collection
 * @since 1.8
 */
default Stream<E> stream() {
    return StreamSupport.stream(spliterator(), false);
}
 

/**
 * Returns a sequential {@code Stream} with this collection as its source.
 *
 * <p>This method should be overridden when the {@link #spliterator()}
 * method cannot return a spliterator that is {@code IMMUTABLE},
 * {@code CONCURRENT}, or <em>late-binding</em>. (See {@link #spliterator()}
 * for details.)
 *
 * @implSpec
 * The default implementation creates a sequential {@code Stream} from the
 * collection's {@code Spliterator}.
 *
 * @return a sequential {@code Stream} over the elements in this collection
 * @since 1.8
 */
default Stream<E> stream() {
    return StreamSupport.stream(spliterator(), false);
}