Kafka学习（二）消费者

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消费者：

（1）配置：

@Configuration
@EnableKafka
public class KafkaConsumerConfig {
    @Value("${spring.kafka.bootstrap-servers}")
    private String brokers;

    @Value("${spring.kafka.consumer.group-id}")
    private String group;

    @Value("${spring.kafka.consumer.key-deserializer}")
    private String keyType;

    @Value("${spring.kafka.consumer.value-deserializer}")
    private String valueType;

    @Bean
    public KafkaListenerContainerFactory<ConcurrentMessageListenerContainer<String, String>> kafkaListenerContainerFactory() {

        ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<String, String>();
        factory.setConsumerFactory(consumerFactory());
        factory.setConcurrency(4);
        factory.getContainerProperties().setPollTimeout(4000);
        return factory;
    }

    @Bean
    public KafkaListeners kafkaListeners() {
        return new KafkaListeners() {
            @Override
            public boolean equals(Object obj) {
                return false;
            }

            @Override
            public int hashCode() {
                return 0;
            }

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

            @Override
            public Class<? extends Annotation> annotationType() {
                return null;
            }

            @Override
            public KafkaListener[] value() {
                return new KafkaListener[0];
            }
        };
    }

    public ConsumerFactory<String, String> consumerFactory() {

        Map<String, Object> properties = new HashMap<String, Object>();

        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokers);
        properties.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, false);
        properties.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, "100");
        properties.put(ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG, "15000");
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, keyType);
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, valueType);
        properties.put(ConsumerConfig.GROUP_ID_CONFIG, group);
        properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "latest");

        return new DefaultKafkaConsumerFactory<String, String>(properties);
    }
}

（2）消费：

@Component
public class KafkaConsumer {

    private static final Logger log = LoggerFactory.getLogger(KafkaConsumer.class);

    @Autowired
    private ObjectMapper objectMapper;

    @Autowired
    private RestTemplate restTemplate;

    @Autowired
    private KafkaTemplate kafkaTemplate;

    @KafkaListener(topics = {KafkaMessageConfig.BUSINESS_SERVICE_TOPIC})
    public void processMessage(ConsumerRecord<String, String> consumer) {
        try {
            String topic = "";
            String key = "";
            String message = "";
            if (consumer.topic() != null) {
                topic = consumer.topic();
            }
            if (consumer.key() != null) {
                key = consumer.key();
            }
            if (consumer.value() != null) {
                message = consumer.value();
            }

            if (topic == null || "".equals(topic.trim()) || " ".equals(topic)) {
                log.warn("[processMessage] invalid topic {}", topic);
                return;
            }
            if (key == null || "".equals(key.trim()) || " ".equals(key)) {
                log.warn("[processMessage] invalid key {}", key);
                return;
            }
            if (!new JsonValidator().validate(message)) {
                log.warn("[processMessage] invalid message string {}", message);
                return;
            }

            Map<String, Object> body = JsonUtil.json2Bean(message, Map.class);
            Map<String, Object> params = new HashMap<>();
            if (body == null || body.isEmpty() || !body.containsKey("OperationType")) {
                log.warn("[processMessage] invalid message string {}", message);
                return;
            }
}