Java Code Examples for kafka.javaapi.consumer.SimpleConsumer#fetch()

public static void main(String[] args) throws Exception {
	final String topic = "topic1";
	String clientID = "DemoLowLevelConsumer1";
	SimpleConsumer simpleConsumer = new SimpleConsumer("kafka0", 9092, 100000, 64 * 1000000, clientID);
	FetchRequest req = new FetchRequestBuilder().clientId(clientID)
			.addFetch(topic, 0, 0L, 50).addFetch(topic, 1, 0L, 5000).addFetch(topic, 2, 0L, 1000000).build();
	FetchResponse fetchResponse = simpleConsumer.fetch(req);
	ByteBufferMessageSet messageSet = (ByteBufferMessageSet) fetchResponse.messageSet(topic, 0);
	for (MessageAndOffset messageAndOffset : messageSet) {
		ByteBuffer payload = messageAndOffset.message().payload();
		long offset = messageAndOffset.offset();
		byte[] bytes = new byte[payload.limit()];
		payload.get(bytes);
		System.out.println("Offset:" + offset + ", Payload:" + new String(bytes, "UTF-8"));
	}
}
 

public List<byte[]> readMessages(String topic) {
  SimpleConsumer consumer = new SimpleConsumer("localhost", 6667, 100000, 64 * 1024, "consumer");
  FetchRequest req = new FetchRequestBuilder()
          .clientId("consumer")
          .addFetch(topic, 0, 0, 100000)
          .build();
  FetchResponse fetchResponse = consumer.fetch(req);
  Iterator<MessageAndOffset> results = fetchResponse.messageSet(topic, 0).iterator();
  List<byte[]> messages = new ArrayList<>();
  while(results.hasNext()) {
    ByteBuffer payload = results.next().message().payload();
    byte[] bytes = new byte[payload.limit()];
    payload.get(bytes);
    messages.add(bytes);
  }
  consumer.close();
  return messages;
}
 

public static void main(String[] args) throws Exception {
    generateData();

    SimpleConsumer simpleConsumer = new SimpleConsumer(KafkaProperties.KAFKA_SERVER_URL,
        KafkaProperties.KAFKA_SERVER_PORT,
        KafkaProperties.CONNECTION_TIMEOUT,
        KafkaProperties.KAFKA_PRODUCER_BUFFER_SIZE,
        KafkaProperties.CLIENT_ID);

    System.out.println("Testing single fetch");
    FetchRequest req = new FetchRequestBuilder()
        .clientId(KafkaProperties.CLIENT_ID)
        .addFetch(KafkaProperties.TOPIC2, 0, 0L, 100)
        .build();
    FetchResponse fetchResponse = simpleConsumer.fetch(req);
    printMessages(fetchResponse.messageSet(KafkaProperties.TOPIC2, 0));

    System.out.println("Testing single multi-fetch");
    Map<String, List<Integer>> topicMap = new HashMap<String, List<Integer>>();
    topicMap.put(KafkaProperties.TOPIC2, Collections.singletonList(0));
    topicMap.put(KafkaProperties.TOPIC3, Collections.singletonList(0));
    req = new FetchRequestBuilder()
        .clientId(KafkaProperties.CLIENT_ID)
        .addFetch(KafkaProperties.TOPIC2, 0, 0L, 100)
        .addFetch(KafkaProperties.TOPIC3, 0, 0L, 100)
        .build();
    fetchResponse = simpleConsumer.fetch(req);
    int fetchReq = 0;
    for (Map.Entry<String, List<Integer>> entry : topicMap.entrySet()) {
        String topic = entry.getKey();
        for (Integer offset : entry.getValue()) {
            System.out.println("Response from fetch request no: " + ++fetchReq);
            printMessages(fetchResponse.messageSet(topic, offset));
        }
    }
}
 

/**
 * Makes a call to kafka to fetch messages.
 */
private FetchResponse fetchMessages(SimpleConsumer consumer, long offset) {
  FetchRequest request = new FetchRequestBuilder()
    .clientId(consumer.clientId())
    .addFetch(topicPart.getTopic(), topicPart.getPartition(), offset, FETCH_SIZE)
    .maxWait(MAX_WAIT)
    .build();
  return consumer.fetch(request);
}
 

private void initializeLastProcessingOffset()
{
  // read last received kafka message
  TopicMetadata tm = KafkaMetadataUtil.getTopicMetadata(Sets.newHashSet((String)getConfigProperties().get(KafkaMetadataUtil.PRODUCER_PROP_BROKERLIST)), this.getTopic());

  if (tm == null) {
    throw new RuntimeException("Failed to retrieve topic metadata");
  }

  partitionNum = tm.partitionsMetadata().size();

  lastMsgs = new HashMap<Integer, Pair<byte[],byte[]>>(partitionNum);

  for (PartitionMetadata pm : tm.partitionsMetadata()) {

    String leadBroker = pm.leader().host();
    int port = pm.leader().port();
    String clientName = this.getClass().getName().replace('$', '.') + "_Client_" + tm.topic() + "_" + pm.partitionId();
    SimpleConsumer consumer = new SimpleConsumer(leadBroker, port, 100000, 64 * 1024, clientName);

    long readOffset = KafkaMetadataUtil.getLastOffset(consumer, tm.topic(), pm.partitionId(), kafka.api.OffsetRequest.LatestTime(), clientName);

    FetchRequest req = new FetchRequestBuilder().clientId(clientName).addFetch(tm.topic(), pm.partitionId(), readOffset - 1, 100000).build();

    FetchResponse fetchResponse = consumer.fetch(req);
    for (MessageAndOffset messageAndOffset : fetchResponse.messageSet(tm.topic(), pm.partitionId())) {

      Message m = messageAndOffset.message();

      ByteBuffer payload = m.payload();
      ByteBuffer key = m.key();
      byte[] valueBytes = new byte[payload.limit()];
      byte[] keyBytes = new byte[key.limit()];
      payload.get(valueBytes);
      key.get(keyBytes);
      lastMsgs.put(pm.partitionId(), new Pair<byte[], byte[]>(keyBytes, valueBytes));
    }
  }
}
 

private synchronized FetchResponse getFetchResponseForFetchRequest(FetchRequest fetchRequest,
    KafkaPartition partition) {
  SimpleConsumer consumer = getSimpleConsumer(partition.getLeader().getHostAndPort());

  FetchResponse fetchResponse = consumer.fetch(fetchRequest);
  if (fetchResponse.hasError()) {
    throw new RuntimeException(
        String.format("error code %d", fetchResponse.errorCode(partition.getTopicName(), partition.getId())));
  }
  return fetchResponse;
}
 

private synchronized FetchResponse getFetchResponseForFetchRequest(FetchRequest fetchRequest, KafkaPartition partition) {
  SimpleConsumer consumer = getSimpleConsumer(partition.getLeader().getHostAndPort());

  FetchResponse fetchResponse = consumer.fetch(fetchRequest);
  if (fetchResponse.hasError()) {
    throw new RuntimeException(String.format("error code %d",
        fetchResponse.errorCode(partition.getTopicName(), partition.getId())));
  }
  return fetchResponse;
}
 

public static ByteBufferMessageSet fetchMessages(KafkaConfig config, SimpleConsumer consumer, Partition partition, long offset) {
    ByteBufferMessageSet msgs = null;
    String topic = config.topic;
    int partitionId = partition.partition;
    for (int errors = 0; errors < 2 && msgs == null; errors++) {
        FetchRequestBuilder builder = new FetchRequestBuilder();
        FetchRequest fetchRequest = builder.addFetch(topic, partitionId, offset, config.fetchSizeBytes).
                clientId(config.clientId).build();
        FetchResponse fetchResponse;
        try {
            fetchResponse = consumer.fetch(fetchRequest);
        } catch (Exception e) {
            if (e instanceof ConnectException) {
                throw new FailedFetchException(e);
            } else {
                throw new RuntimeException(e);
            }
        }
        if (fetchResponse.hasError()) {
            KafkaError error = KafkaError.getError(fetchResponse.errorCode(topic, partitionId));
            if (error.equals(KafkaError.OFFSET_OUT_OF_RANGE) && config.useStartOffsetTimeIfOffsetOutOfRange && errors == 0) {
                long startOffset = getOffset(consumer, topic, partitionId, config.startOffsetTime);
                LOG.warn("Got fetch request with offset out of range: [" + offset + "]; " +
                        "retrying with default start offset time from configuration. " +
                        "configured start offset time: [" + config.startOffsetTime + "] offset: [" + startOffset + "]");
                offset = startOffset;
            } else {
                String message = "Error fetching data from [" + partition + "] for topic [" + topic + "]: [" + error + "]";
                LOG.error(message);
                throw new FailedFetchException(message);
            }
        } else {
            msgs = fetchResponse.messageSet(topic, partitionId);
        }
    }
    return msgs;
}
 

public List<Message> getMesage(String topicName, int partitionID, int offset, int count) {
    Topic topic = kafkaService.getTopic(topicName);
    Partition partition = topic.getPartition(partitionID);
    Broker broker = kafkaService.getBrokerById(partition.getLeader().getId());

    SimpleConsumer consumer = new SimpleConsumer(broker.getHost(), broker.getPort(), 10000, 10000, "");
    FetchRequestBuilder requestBuilder = new FetchRequestBuilder()
            .clientId("kafkaMonitor")
            .maxWait(5000)
            .minBytes(1);
    List<Message> messageList = new ArrayList<>(count);
    long currentOffset = offset;
    while (messageList.size() < count) {
        kafka.api.FetchRequest request = requestBuilder.addFetch(topicName, partitionID, currentOffset, 1024 * 1024).build();

        kafka.javaapi.FetchResponse response = consumer.fetch(request);
        ByteBufferMessageSet messageSet = response.messageSet(topicName, partitionID);
        if (messageSet.validBytes() <= 0) break;

        int oldSize = messageList.size();
        StreamSupport.stream(messageSet.spliterator(), false)
                .limit(count - messageList.size())
                .map(MessageAndOffset::message)
                .map((msg) -> {
                    Message mmsg = new Message();
                    if (msg.hasKey()) {
                        mmsg.setKey(readString(msg.key()));
                    }
                    if (!msg.isNull()) {
                        mmsg.setMessage(readString(msg.payload()));
                    }
                    mmsg.setValid(msg.isValid());
                    mmsg.setCompressionCodec(msg.compressionCodec().name());
                    mmsg.setChecksum(msg.checksum());
                    return mmsg;
                }).forEach(messageList::add);
        currentOffset += messageList.size() - oldSize;

    }
    consumer.close();
    return messageList;
}
 

private static void consumeMessage(Arguments arguments) {

        Properties properties = new Properties();
        properties.put(SimpleConsumer.HTTP_SERVICE_URL, arguments.httpServiceUrl);
        SimpleConsumer consumer = new SimpleConsumer(arguments.serviceUrl, 0, 0, 0, "clientId", properties);

        long readOffset = kafka.api.OffsetRequest.EarliestTime();
        kafka.api.FetchRequest fReq = new FetchRequestBuilder().clientId("c1")
                .addFetch(arguments.topicName, arguments.partitionIndex, readOffset, 100000).build();
        FetchResponse fetchResponse = consumer.fetch(fReq);

        TestDecoder decoder = new TestDecoder();
        int count = 0;
        while (count < arguments.totalMessages || arguments.totalMessages == -1) {
            // 1. Read from topic without subscription/consumer-group name.
            for (MessageAndOffset messageAndOffset : fetchResponse.messageSet(arguments.topicName,
                    arguments.partitionIndex)) {
                MessageId msgIdOffset = (messageAndOffset instanceof PulsarMsgAndOffset)
                        ? ((PulsarMsgAndOffset) messageAndOffset).getFullOffset()
                        : null;
                long currentOffset = messageAndOffset.offset();
                if (currentOffset < readOffset) {
                    continue;
                }

                ByteBuffer payload = messageAndOffset.message().payload();

                byte[] bytes = new byte[payload.limit()];
                payload.get(bytes);
                Tweet tweet = decoder.fromBytes(bytes);
                log.info("Received tweet: {}-{}", tweet.userName, tweet.message);
                count++;

                TopicAndPartition topicPartition = new TopicAndPartition(arguments.topicName, arguments.partitionIndex);
                OffsetMetadataAndError offsetError = new OffsetMetadataAndError(msgIdOffset, null, (short) 0);
                Map<TopicAndPartition, OffsetMetadataAndError> requestInfo = Collections.singletonMap(topicPartition,
                        offsetError);
                // 2. Commit offset for a given topic and subscription-name/consumer-name.
                OffsetCommitRequest offsetReq = new OffsetCommitRequest(arguments.groupName, requestInfo, (short) -1, 0,
                        "c1");
                consumer.commitOffsets(offsetReq);
            }
        }

        consumer.close();
    }
 

private Message getMessage(TopicPartition topicPartition, long offset,
                           SimpleConsumer consumer) {
    LOG.debug("fetching message topic {} partition {} offset {}",
            topicPartition.getTopic(), topicPartition.getPartition(), offset);
    final int MAX_MESSAGE_SIZE_BYTES = mConfig.getMaxMessageSizeBytes();
    final String clientName = getClientName(topicPartition);
    kafka.api.FetchRequest request = new FetchRequestBuilder().clientId(clientName)
            .addFetch(topicPartition.getTopic(), topicPartition.getPartition(), offset,
                      MAX_MESSAGE_SIZE_BYTES)
            .build();
    FetchResponse response = consumer.fetch(request);
    if (response.hasError()) {
        consumer.close();
        int errorCode = response.errorCode(topicPartition.getTopic(), topicPartition.getPartition());

        if (errorCode == Errors.OFFSET_OUT_OF_RANGE.code()) {
          throw new MessageDoesNotExistException();
        } else {
          throw new RuntimeException("Error fetching offset data. Reason: " + errorCode);
        }
    }
    MessageAndOffset messageAndOffset = response.messageSet(
            topicPartition.getTopic(), topicPartition.getPartition()).iterator().next();
    byte[] keyBytes = null;
    if (messageAndOffset.message().hasKey()) {
        ByteBuffer key = messageAndOffset.message().key();
        keyBytes = new byte[key.limit()];
        key.get(keyBytes);
    }
    byte[] payloadBytes = null;
    if (!messageAndOffset.message().isNull()) {
        ByteBuffer payload = messageAndOffset.message().payload();
        payloadBytes = new byte[payload.limit()];
        payload.get(payloadBytes);
    }
    long timestamp = (mConfig.useKafkaTimestamp())
            ? mKafkaMessageTimestampFactory.getKafkaMessageTimestamp().getTimestamp(messageAndOffset)
            : 0l;

    return new Message(topicPartition.getTopic(), topicPartition.getPartition(),
            messageAndOffset.offset(), keyBytes, payloadBytes, timestamp, null);
}
 

@Test
public void testDefaultParameters() throws IOException {
    TopicCommand.createTopic(zk.getZkClient(),
            new TopicCommand.TopicCommandOptions(new String[]{
                    "--zookeeper", "dummy", "--create", "--topic", TOPIC_NAME,
                    "--replication-factor", "2", "--partitions", "1"}));
    String description = "{\n" +
            "    \"type\": \"kafka\",\n" +
            "    \"client.id\": \"kafkasink\",\n" +
            "    \"bootstrap.servers\": \"" + kafkaServer.getBrokerListStr() + "\",\n" +
            "    \"acks\": 1\n" +
            "}";


    KafkaSink sink = jsonMapper.readValue(description, new TypeReference<Sink>(){});
    sink.open();
    Iterator<Message> msgIterator = new MessageSetReader(createMessageSet(TOPIC_NAME, 2)).iterator();
    while (msgIterator.hasNext()) {
        sink.writeTo(new StringMessage(msgIterator.next()));
    }
    assertTrue(sink.getNumOfPendingMessages() > 0);
    sink.close();
    assertEquals(sink.getNumOfPendingMessages(), 0);
    System.out.println(sink.getStat());

    // get the leader
    Option<Object> leaderOpt = ZkUtils.getLeaderForPartition(zk.getZkClient(), TOPIC_NAME, 0);
    assertTrue("Leader for topic new-topic partition 0 should exist", leaderOpt.isDefined());
    int leader = (Integer) leaderOpt.get();

    KafkaConfig config;
    if (leader == kafkaServer.getServer(0).config().brokerId()) {
        config = kafkaServer.getServer(0).config();
    } else {
        config = kafkaServer.getServer(1).config();
    }
    SimpleConsumer consumer = new SimpleConsumer(config.hostName(), config.port(), 100000, 100000, "clientId");
    FetchResponse response = consumer.fetch(new FetchRequestBuilder().addFetch(TOPIC_NAME, 0, 0, 100000).build());

    List<MessageAndOffset> messageSet = Lists.newArrayList(response.messageSet(TOPIC_NAME, 0).iterator());
    assertEquals("Should have fetched 2 messages", 2, messageSet.size());

    assertEquals(new String(extractMessage(messageSet, 0)), "testMessage" + 0);
    assertEquals(new String(extractMessage(messageSet, 1)), "testMessage" + 1);
}
 

@Test
public void testDefaultParameters() throws IOException {
    TopicCommand.createTopic(zk.getZkClient(),
            new TopicCommand.TopicCommandOptions(new String[]{
                    "--zookeeper", "dummy", "--create", "--topic", TOPIC_NAME,
                    "--replication-factor", "2", "--partitions", "1"}));
    String description = "{\n" +
            "    \"type\": \"kafka\",\n" +
            "    \"client.id\": \"kafkasink\",\n" +
            "    \"metadata.broker.list\": \"" + kafkaServer.getBrokerListStr() + "\",\n" +
            "    \"request.required.acks\": 1\n" +
            "}";

    ObjectMapper jsonMapper = new DefaultObjectMapper();
    jsonMapper.registerSubtypes(new NamedType(KafkaSinkV2.class, "kafka"));
    KafkaSinkV2 sink = jsonMapper.readValue(description, new TypeReference<Sink>(){});
    sink.open();
    // create send test messages to Kafka
    Iterator<Message> msgIterator = new MessageSetReader(createMessageSet(TOPIC_NAME, 2)).iterator();
    HashSet<String> sentPayloads = new HashSet<String>(); // track sent messages for comparison later
    while (msgIterator.hasNext()) {
        StringMessage next = new StringMessage(msgIterator.next());
        sink.writeTo(next); // send
        sentPayloads.add( new String( next.getMessage().getPayload() ) ); // record
    }
    sink.close();
    assertEquals(sink.getNumOfPendingMessages(), 0);
    System.out.println(sink.getStat());

    // get the leader
    Option<Object> leaderOpt = ZkUtils.getLeaderForPartition(zk.getZkClient(), TOPIC_NAME, 0);
    assertTrue("Leader for topic new-topic partition 0 should exist", leaderOpt.isDefined());
    int leader = (Integer) leaderOpt.get();

    KafkaConfig config;
    if (leader == kafkaServer.getServer(0).config().brokerId()) {
        config = kafkaServer.getServer(0).config();
    } else {
        config = kafkaServer.getServer(1).config();
    }
    // get data back from Kafka
    SimpleConsumer consumer = new SimpleConsumer(config.hostName(), config.port(), 100000, 100000, "clientId");
    FetchResponse response = consumer.fetch(new FetchRequestBuilder().addFetch(TOPIC_NAME, 0, 0, 100000).build());

    List<MessageAndOffset> messageSet = Lists.newArrayList(response.messageSet(TOPIC_NAME, 0).iterator());
    assertEquals("Should have fetched 2 messages", 2, messageSet.size());

    for( int i=0; i<messageSet.size(); i++ ){
        // ensure that received message was one that was sent
        String receivedPayload = new String(extractMessage(messageSet, i));
        System.out.println( "Got message: " + new String( receivedPayload ) );
        assert( sentPayloads.remove( receivedPayload ) );
    }
    assertEquals(sentPayloads.size(), 0); // all sent messages should have been received
}
 

public ByteBufferMessageSet fetchMessages(int partition, long offset) throws IOException {

        String topic = config.topic;
        FetchRequest req = new FetchRequestBuilder().clientId(config.clientId).addFetch(topic, partition, offset, config.fetchMaxBytes)
                .maxWait(config.fetchWaitMaxMs).build();
        FetchResponse fetchResponse = null;
        SimpleConsumer simpleConsumer = null;
        try {
            simpleConsumer = findLeaderConsumer(partition);
            if (simpleConsumer == null) {
                // LOG.error(message);
                return null;
            }
            fetchResponse = simpleConsumer.fetch(req);
        } catch (Exception e) {
            if (e instanceof ConnectException || e instanceof SocketTimeoutException || e instanceof IOException
                    || e instanceof UnresolvedAddressException) {
                LOG.warn("Network error when fetching messages:", e);
                if (simpleConsumer != null) {
                    String host = simpleConsumer.host();
                    int port = simpleConsumer.port();
                    simpleConsumer = null;
                    throw new KafkaException("Network error when fetching messages: " + host + ":" + port + " , " + e.getMessage(), e);
                }

            } else {
                throw new RuntimeException(e);
            }
        }
        if (fetchResponse.hasError()) {
            short code = fetchResponse.errorCode(topic, partition);
            if (code == ErrorMapping.OffsetOutOfRangeCode() && config.resetOffsetIfOutOfRange) {
                long startOffset = getOffset(topic, partition, config.startOffsetTime);
                offset = startOffset;
            }
            if(leaderBroker != null) {
                LOG.error("fetch data from kafka topic[" + config.topic + "] host[" + leaderBroker.host() + ":" + leaderBroker.port() + "] partition["
                    + partition + "] error:" + code);
            }else {
                
            }
            return null;
        } else {
            ByteBufferMessageSet msgs = fetchResponse.messageSet(topic, partition);
            return msgs;
        }
    }