如何使用kafka客户端以便使用Java语言从主题中进行消费

Question

我正在尝试使用我知道会产生消息的主题中的消息（kafka生产者已经通过设计存在，我要做的就是编写使用消息的代码）。

这是我的代码：

public class ConsumerManager extends ShutdownableThread {

    //    private final KafkaConsumer<String, String> kafkaConsumer;
//    static String brokers = Configuration.prop.getProperty("suite.pusher.defaultParams.kafkaBrokers");
    static String brokers = "<kafka_server_ip>:9092";
    static private Producer<String, String> m_kafkaProducers;
    static private int m_CurrentProducerIndex;
    static private int maxKafkaMessageSizeInMb = 8;
    static private String kafkaCompressionCodec = "lz4";
    static private String maxKafkaAcks = "1";
    static private int maxKafkaRetries;
    static private int kafkaBatchSize = 16384;
    static private int kafkaBufferMemory = 33554432;
    static private int kafkaConnectionsMaxIdleMs = 540000;
    static private int kafkaLingerMs = 0;
    static private int kafkaMaxBlocks = 100;
    static private int kafkaMaxRequestSize = 1048576;
    static private int kafkaRequestTimeoutMs = 300000;
    static private int kafkaMaxInFlightRequestsPerConnection = 5;
    static private int kafkaBatchNumMessages = 10000;
    static private int kafkeQueueBufferingMaxMs = 10;
    static private int kafkaFetchWaitMaxMs = 10;
    static private int kafkaSocketBlockingMaxMs = 10;
    static private boolean kafkaSocketNagleDisable = false;
    String kafkaPrefix = Configuration.prop.getProperty("suite.pusher.defaultParams.kafkaTopicPrefix");

    private final Boolean isAsync = false;
    static String TOPIC = "proc_422_26952";//"proc_69686_61";//" "qa_69313_2";
    private final KafkaConsumer<String, String> consumer;
    private final String topics;

    public ConsumerManager(String topic) {
        super("KafkaConsumerExample", false);
        Properties props = new Properties();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "CageConsumerGroup");
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "true");
        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "1000");
        props.put(ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG, "30000");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, "org.apache.kafka.common.serialization.StringDeserializer");
        consumer = new KafkaConsumer<String, String>(props);
        this.topics = topic;

    }
    @Override
    public void doWork() {
        consumer.subscribe(Collections.singletonList(this.topics));
        ConsumerRecords<String, String> records = consumer.poll(10000);
        for (ConsumerRecord<String, String> record : records) {
            System.out.println("Received message: (" + record.key() + ", " + record.value() + ") at offset " + record.offset());
        }
    }

    @Override
    public String name() {
        return null;
    }

    @Override
    public boolean isInterruptible() {
        return false;
    }
}

但是，当我上一行时： ConsumerRecords<String, String> records = consumer.poll(10000); 没有任何反应，测试完成，我无法查看记录或知道该主题收到了消息，然后可以将它们显示在控制台上。

我想念什么？

Answer 1

好，

我从头开始更改了所有消费者类，现在似乎可以使用了，这是我的代码：

public class ConsumerManager  {

    static String brokers = "<kafka_host>:9092";
    private ExecutorService executor;
    String kafkaPrefix = "proc_422_26952";
    private final Boolean isAsync = false;
    static String TOPIC; //"proc_69686_61";//" "qa_69313_2";

    public ConsumerManager(String topicName) {

        TOPIC = topicName;
        Properties props = new Properties();

        props.put("bootstrap.servers", brokers);
        props.put("group.id", "CageConsumerGroupIO");
        props.put("enable.auto.commit", "true");
        props.put("auto.commit.interval.ms", "1000");
        props.put("session.timeout.ms", "30000");
        props.put("max.poll.records", "500");
        props.put("key.deserializer",
                "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer",
                "org.apache.kafka.common.serialization.StringDeserializer");
        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);

        consumer.subscribe(Arrays.asList(TOPIC));
        System.out.println("Subscribed to topic " + TOPIC);
        int i = 0;

        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);

            for (ConsumerRecord<String, String> record : records) {
                System.out.printf("offset = %d, key = %s, value = %s\n",
                        record.offset(), record.key(), record.value());
                System.out.println(record.value());
            }


        }
    }