java.util.stream.Stream#findFirst ( )源码实例Demo

private Attestation createAttestation(
    final BeaconBlockAndState blockAndState,
    final boolean withValidSignature,
    final UnsignedLong slot) {
  UnsignedLong assignedSlot = slot;

  Optional<Attestation> attestation = Optional.empty();
  while (attestation.isEmpty()) {
    Stream<Attestation> attestations =
        withValidSignature
            ? streamAttestations(blockAndState, assignedSlot)
            : streamInvalidAttestations(blockAndState, assignedSlot);
    attestation = attestations.findFirst();
    assignedSlot = assignedSlot.plus(UnsignedLong.ONE);
  }

  return attestation.orElseThrow();
}
 

@Test
public void failsToProcessDeletedStream() {
    final String stream = generateStreamName();

    eventstore.deleteStream(stream, ExpectedVersion.NO_STREAM, true).join();

    Stream<ResolvedEvent> eventStream = eventstore.streamEventsForward(stream, 0, 5, false);

    try {
        eventStream.findFirst();
        fail("should fail with 'StreamDeletedException'");
    } catch (Exception e) {
        assertThat(e, instanceOf(StreamDeletedException.class));
        assertEquals(stream, ((StreamDeletedException) e).stream);
    }
}
 

@Test
public void failsToProcessDeletedStream() {
    final String stream = generateStreamName();

    eventstore.deleteStream(stream, ExpectedVersion.NO_STREAM, true).join();

    Stream<ResolvedEvent> eventStream = eventstore.streamEventsBackward(stream, 0, 5, false);

    try {
        eventStream.findFirst();
        fail("should fail with 'StreamDeletedException'");
    } catch (Exception e) {
        assertThat(e, instanceOf(StreamDeletedException.class));
        assertEquals(stream, ((StreamDeletedException) e).stream);
    }
}
 

/**
 * Try to find a parallel environment that can be used to get a number of cores on a single node
 *
 * @param coresPerNode
 *            number of cores to reserve on a node
 * @param queueName
 *            Name of the queue
 * @return optional parallel environment
 */
Optional<ParallelEnvironmentInfo> getSingleNodeParallelEnvironment(int coresPerNode, String queueName) {
    Stream<ParallelEnvironmentInfo> stream = this.parallelEnvironments.values().stream().filter(pe -> pe.canAllocateSingleNode(coresPerNode));
    // Filter pe on queue
    QueueInfo queue = queues.get(queueName);
    if (queue == null) {
        Set<String> pesOfQueues = new HashSet<>();
        for (QueueInfo q : queues.values()) {
            pesOfQueues.addAll(Arrays.asList(q.getParallelEnvironments()));
        }
        stream = stream.filter(pe -> pesOfQueues.contains(pe.getName()));
    } else {
        // don't know which queue the scheduler will pick, make sure at least one queue has the candidate pe
        Set<String> pesOfQueue = new HashSet<>(Arrays.asList(queue.getParallelEnvironments()));
        stream = stream.filter(pe -> pesOfQueue.contains(pe.getName()));
    }
    Optional<ParallelEnvironmentInfo> r = stream.findFirst();
    LOGGER.debug("Gridengine choose to use following pe: " + r.toString());
    return r;
}
 

/**
 * Tries to get the mac address of the first device in alphabetic order, should be eth or en in most cases.
 * <p>
 * Warning: this method can take seconds to execute
 *
 * @return the first found hardware address
 * @throws SocketException
 * 		if an I/O error occurs.
 * @throws InvalidResultException
 * 		if no non-loopback network device exists.
 * @throws NullPointerException
 * 		if no network device exists.
 */
static String getHardwareAddress() throws SocketException {
	//Use hardware addresses as seed
	Stream<NetworkInterface> sortedStream = Collections.list(NetworkInterface.getNetworkInterfaces()).stream().filter(i -> {
		try {
			return i.getHardwareAddress() != null;
		} catch (SocketException e) {
			return false;
		}
	}).sorted(Comparator.comparing(NetworkInterface::getName));
	Optional<NetworkInterface> result = sortedStream.findFirst();
	if (!result.isPresent()) {
		throw new InvalidResultException("No non-loopback network interface exists");
	}
	return DatatypeConverter.printHexBinary(result.get().getHardwareAddress());
}
 

/**
 * Peeks for the feature and outcome dimensions.
 * 
 * @param streamSupplier the supplier that gets streams.
 */
@VisibleForTesting
protected void peekDimensions(
    Supplier<Stream<FeatureOutcomePair>> streamSupplier) {
  Stream<FeatureOutcomePair> stream = Preconditions.checkNotNull(
      streamSupplier.get(), "Supplied a null stream!");
  Optional<FeatureOutcomePair> first = stream.findFirst();

  if (!first.isPresent()) {
    throw new IllegalArgumentException("Supplied an empty stream!");
  }

  FeatureOutcomePair firstExample = first.get();
  this.featureDimension = firstExample.getFeature().getDimension();
  this.outcomeDimension = firstExample.getOutcome().getDimension();
  this.numOutcomeClasses = Math.max(2, this.outcomeDimension);
}
 

private IFunctionHandler matchFunctionHandler(NettyHttpRequest request) throws IllegalPathNotFoundException, IllegalMethodNotAllowedException {

        AtomicBoolean matched = new AtomicBoolean(false);

        Stream<Path> stream = functionHandlerMap.keySet().stream()
                .filter(((Predicate<Path>) path -> {
                    /**
                     *过滤 Path URI 不匹配的
                     */
                    if (request.matched(path.getUri(), path.isEqual())) {
                        matched.set(true);
                        return matched.get();
                    }
                    return false;

                }).and(path -> {
                    /**
                     * 过滤 Method 匹配的
                     */
                    return request.isAllowed(path.getMethod());
                }));

        Optional<Path> optional = stream.findFirst();

        stream.close();

        if (!optional.isPresent() && !matched.get()){
            throw  new IllegalPathNotFoundException();
        }

        if (!optional.isPresent() && matched.get()){
            throw  new IllegalMethodNotAllowedException();
        }

        return functionHandlerMap.get(optional.get());
    }
 

@Override
public Stream<TestResultPayload> extract(Stream<TestStep> testSteps) {
    Stream<ScreenshotStepPayload> payloads = testSteps
            .flatMap(s -> s.getCombinedPayloadsOfType(ScreenshotStepPayload.class));

    Optional<ScreenshotStepPayload> first = payloads.findFirst();
    return first.map(screenshotStepPayload -> Stream.of(
            new TestResultPayload("screenshot", screenshotStepPayload.getBase64png())))
            .orElseGet(Stream::empty);
}
 

/**
 * Closes all {@link Producer producers} that have been produced by this pool.
 * <p>
 * Any subsequent invocation of this method is ignored.
 * </p>
 *
 * @throws IOException
 *             if an error occurs during producer closure.
 *
 * {@inheritDoc}
 */
@Override
public void close() throws IOException {
    writeLock.lock();
    try {
        if (!shutdown) {
            shutdown = true;
            final Stream<Exception> exceptions = pool.values().stream()
                    .flatMap(Collection::stream)
                    .flatMap(producer -> {
                        try {
                            producer.close();
                        } catch (Exception e) {
                            LOGGER.error("Could not close producer", e);
                            return Stream.of(e);
                        }
                        return Stream.empty();
                    });

            // Throw exception if any of the producers in the pool could not be closed.
            final Optional<Exception> exception = exceptions.findFirst();
            if (exception.isPresent()) {
                throw new IOException(exception.get());
            }
        }
    } finally {
        writeLock.unlock();
    }
}
 

@Test
public void testParseIdentifier() {
    String mockString = MCRMockIdentifier.MOCK_SCHEME + "http://google.de/";
    Stream<MCRPersistentIdentifier> mcrPersistentIdentifierStream = MCRPIManager
        .getInstance()
        .get(mockString);

    Optional<? extends MCRPersistentIdentifier> mcrMockIdentifier = mcrPersistentIdentifierStream
        .findFirst();
    Assert.assertEquals(mcrMockIdentifier.get().asString(), mockString);
}
 

@Programmatic
public Document findDocument(final String roleName) {
    final Stream<Document> documents = findDocumentsInRoleAsStream(roleName);
    final Optional<Document> documentIfAny = documents.findFirst();
    return documentIfAny.orElseThrow(() -> (RuntimeException)new ApplicationException(String.format(
            "Could not find document (via paperclip with role of '%s')",
            roleName)));
}
 

@Test
public void failsToProcessNonExistingStream() {
    final String stream = generateStreamName();

    Stream<ResolvedEvent> eventStream = eventstore.streamEventsBackward(stream, 0, 5, false);

    try {
        eventStream.findFirst();
        fail("should fail with 'StreamNotFoundException'");
    } catch (Exception e) {
        assertThat(e, instanceOf(StreamNotFoundException.class));
        assertEquals(stream, ((StreamNotFoundException) e).stream);
    }
}
 

@Test
public void shouldGiveLogsInStream() {
    containerId = dockerClient.createContainerCmd(WANTED_IMAGE).withEnv(singletonList("WAITING_TIME=1ms"))
        .exec()
        .getId();
    dockerClient.startContainerCmd(containerId).exec();
    Stream<String> logs = defaultDockerClient.logs(containerId);
    Optional<String> firstLine = logs.findFirst();
    assertThat(firstLine).isPresent()
        .hasValueSatisfying("started"::equals);
}
 

private static void initHttpAll(
        VxmsShared vxmsShared,
        Router router,
        Object service,
        Method restMethod,
        Path path,
        Stream<Method> errorMethodStream,
        Optional<Consumes> consumes) {
    final Optional<Method> errorMethod = errorMethodStream.findFirst();
    final Route route = router.route(URIUtil.cleanPath(path.value()));
    final Context context = getContext(vxmsShared);
    final String methodId =
            path.value() + HTTP_ALL + ConfigurationUtil.getCircuitBreakerIDPostfix(context.config());
    initHttpRoute(methodId, vxmsShared, service, restMethod, consumes, errorMethod, route);
}
 

public AnswerElement checkForwarding(NetworkSnapshot snapshot, HeaderQuestion question) {
  long totalTime = System.currentTimeMillis();
  HeaderQuestion q = new HeaderQuestion(question);
  q.setFailures(0);
  Tuple<Stream<Supplier<NetworkSlice>>, Long> ecs =
      findAllNetworkSlices(q, new Graph(_batfish, snapshot), true);
  Stream<Supplier<NetworkSlice>> stream = ecs.getFirst();
  Long timeAbstraction = ecs.getSecond();
  Optional<Supplier<NetworkSlice>> opt = stream.findFirst();
  if (!opt.isPresent()) {
    throw new BatfishException("Unexpected Error: checkForwarding");
  }
  long timeEc = System.currentTimeMillis();
  Supplier<NetworkSlice> sup = opt.get();
  NetworkSlice slice = sup.get();
  timeEc = System.currentTimeMillis() - timeEc;
  Graph g = slice.getGraph();
  q = new HeaderQuestion(q);
  q.setHeaderSpace(slice.getHeaderSpace());
  long timeEncoding = System.currentTimeMillis();
  Encoder encoder = new Encoder(g, q);
  encoder.computeEncoding();
  addEnvironmentConstraints(encoder, q.getBaseEnvironmentType());
  timeEncoding = System.currentTimeMillis() - timeEncoding;
  VerificationResult result = encoder.verify().getFirst();
  totalTime = System.currentTimeMillis() - totalTime;
  VerificationStats stats = result.getStats();
  if (q.getBenchmark()) {
    stats.setTimeCreateBdds((double) timeAbstraction);
    stats.setTotalTime(totalTime);
    stats.setAvgComputeEcTime(timeEc);
    stats.setMaxComputeEcTime(timeEc);
    stats.setMinComputeEcTime(timeEc);
    stats.setAvgEncodingTime(timeEncoding);
    stats.setMaxEncodingTime(timeEncoding);
    stats.setMinEncodingTime(timeEncoding);
    stats.setTimeCreateBdds((double) timeAbstraction);
  }
  return new SmtOneAnswerElement(result);
}
 

@Test(expected = IllegalStateException.class)
public void givenStream_whenStreamUsedTwice_thenThrowException() {
    Stream<String> stringStream = Stream.of("A", "B", "C", "D");
    Optional<String> result1 = stringStream.findAny();
    System.out.println(result1.get());
    Optional<String> result2 = stringStream.findFirst();
    System.out.println(result2.get());
}
 

@Override
public Comm getCommByTargetName(String targetName) {
  Stream<Map.Entry<String, Comm>> entryStream = commMap.entrySet().stream().filter(x -> x.getValue().getTargetName().equals(targetName));
  Optional<Map.Entry<String, Comm>> first = entryStream.findFirst();
  if (first.isPresent()) {
    return first.get().getValue();
  }
  return null;
}
 

public Optional<MediaSegmentDescriptor> lookUpSegment(String segmentId) {
  Stream<MediaSegmentDescriptor> descriptors =
      this.lookUpSegmentsByField(FIELDNAMES[0], segmentId);
  return descriptors.findFirst();
}
 

/**
 * Starts tests by compiling first generated DTO from maven plugin
 * @throws IOException if unable to start process
 * @throws InterruptedException if unable to wait the end of the process
 */
@Test(dependsOnGroups = "tools")
public void compileDTOAndLaunchTests() throws IOException, InterruptedException {

    // search DTO
    Path p = this.buildDirectory;
    final int maxDepth = 10;
    Stream<Path> matches = java.nio.file.Files.find( p, maxDepth, (path, basicFileAttributes) -> path.getFileName().toString().equals(GENERATED_DTO_NAME));

    // take first
    Optional<Path> optionalPath = matches.findFirst();
    if (!optionalPath.isPresent()) {
        throw new IllegalStateException("Unable to find generated DTO file named '" + GENERATED_DTO_NAME + "'. Check it has been generated first");
    }

    Path generatedDtoPath = optionalPath.get();

    //copy it in test resources folder where package.json is
    java.nio.file.Files.copy(generatedDtoPath, this.rootPath.resolve(DTO_FILENAME), StandardCopyOption.REPLACE_EXISTING);

    matches = java.nio.file.Files.find( p, maxDepth, (path, basicFileAttributes) -> path.getFileName().toString().equals(GENERATED_DTO_DTS_NAME));

    // take first
    optionalPath = matches.findFirst();
    if (!optionalPath.isPresent()) {
        throw new IllegalStateException("Unable to find generated DTO file named '" + GENERATED_DTO_DTS_NAME + "'. Check it has been generated first");
    }

    generatedDtoPath = optionalPath.get();

    //copy it in test resources folder where package.json is
    java.nio.file.Files.copy(generatedDtoPath, this.rootPath.resolve(DTO_DTS_FILENAME), StandardCopyOption.REPLACE_EXISTING);

    // setup command line
    List<String> command = getDockerExec();

    // avoid root permissions in generated files
    if (SystemInfo.isLinux()) {
        command.add(wrapLinuxCommand("npm test"));
    } else {
        command.add("npm test");
    }
    // setup typescript compiler
    ProcessBuilder processBuilder = new ProcessBuilder().command(command).directory(rootPath.toFile()).redirectErrorStream(true).inheritIO();
    Process process = processBuilder.start();

    LOG.info("Starting TypeScript tests...");
    int resultProcess = process.waitFor();

    if (resultProcess != 0) {
        throw new IllegalStateException("DTO has failed to compile");
    }
    LOG.info("TypeScript tests OK");

}
 

/**
 * Finds {@code "dom-module"} element inside the {@code parent}.
 * <p>
 * If {@code id} is provided then {@code "dom-module"} element is searched
 * with the given {@code id} value.
 *
 * @param parent
 *            the parent element
 * @param id
 *            optional id attribute value to search {@code "dom-module"}
 *            element, may be {@code null}
 * @return
 */
static Optional<Element> getDomModule(Element parent, String id) {
    Stream<Element> stream = parent.getElementsByTag("dom-module").stream();
    if (id != null) {
        stream = stream.filter(element -> id.equals(element.id()));
    }
    return stream.findFirst();
}