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本文主要简单梳理梳理java应用中生产/消费kafka消息的一些使用选择。

可用类库

• kafka client
• spring for apache kafka
• spring integration kafka
• spring cloud stream binder kafka

除了官方的java api类库外，spring生态中又额外包装了很多，这里一一简单介绍下。

spring for apache kafka

基于java版的kafka client与spring进行集成

<dependency>
  <groupId>org.springframework.kafka</groupId>
  <artifactId>spring-kafka</artifactId>
  <version>1.2.2.RELEASE</version>
</dependency>

与springboot的集成

对于springboot 1.5版本之前的话，需要自己去配置java configuration，而1.5版本以后则提供了auto config，具体详见org.springframework.boot.autoconfigure.kafka这个包，主要有

• KafkaAutoConfiguration
  spring-boot-autoconfigure-1.5.7.RELEASE-sources.jar!/org/springframework/boot/autoconfigure/kafka/KafkaAutoConfiguration.java

@Configuration
@ConditionalOnClass(KafkaTemplate.class)
@EnableConfigurationProperties(KafkaProperties.class)
@Import(KafkaAnnotationDrivenConfiguration.class)
public class KafkaAutoConfiguration {

    private final KafkaProperties properties;

    public KafkaAutoConfiguration(KafkaProperties properties) {
        this.properties = properties;
    }

    @Bean
    @ConditionalOnMissingBean(KafkaTemplate.class)
    public KafkaTemplate<?, ?> kafkaTemplate(
            ProducerFactory<Object, Object> kafkaProducerFactory,
            ProducerListener<Object, Object> kafkaProducerListener) {
        KafkaTemplate<Object, Object> kafkaTemplate = new KafkaTemplate<Object, Object>(
                kafkaProducerFactory);
        kafkaTemplate.setProducerListener(kafkaProducerListener);
        kafkaTemplate.setDefaultTopic(this.properties.getTemplate().getDefaultTopic());
        return kafkaTemplate;
    }

    @Bean
    @ConditionalOnMissingBean(ProducerListener.class)
    public ProducerListener<Object, Object> kafkaProducerListener() {
        return new LoggingProducerListener<Object, Object>();
    }

    @Bean
    @ConditionalOnMissingBean(ConsumerFactory.class)
    public ConsumerFactory<?, ?> kafkaConsumerFactory() {
        return new DefaultKafkaConsumerFactory<Object, Object>(
                this.properties.buildConsumerProperties());
    }

    @Bean
    @ConditionalOnMissingBean(ProducerFactory.class)
    public ProducerFactory<?, ?> kafkaProducerFactory() {
        return new DefaultKafkaProducerFactory<Object, Object>(
                this.properties.buildProducerProperties());
    }

}

• KafkaAnnotationDrivenConfiguration
  spring-boot-autoconfigure-1.5.7.RELEASE-sources.jar!/org/springframework/boot/autoconfigure/kafka/KafkaAnnotationDrivenConfiguration.java

@Configuration
@ConditionalOnClass(EnableKafka.class)
class KafkaAnnotationDrivenConfiguration {

    private final KafkaProperties properties;

    KafkaAnnotationDrivenConfiguration(KafkaProperties properties) {
        this.properties = properties;
    }

    @Bean
    @ConditionalOnMissingBean
    public ConcurrentKafkaListenerContainerFactoryConfigurer kafkaListenerContainerFactoryConfigurer() {
        ConcurrentKafkaListenerContainerFactoryConfigurer configurer = new ConcurrentKafkaListenerContainerFactoryConfigurer();
        configurer.setKafkaProperties(this.properties);
        return configurer;
    }

    @Bean
    @ConditionalOnMissingBean(name = "kafkaListenerContainerFactory")
    public ConcurrentKafkaListenerContainerFactory<?, ?> kafkaListenerContainerFactory(
            ConcurrentKafkaListenerContainerFactoryConfigurer configurer,
            ConsumerFactory<Object, Object> kafkaConsumerFactory) {
        ConcurrentKafkaListenerContainerFactory<Object, Object> factory = new ConcurrentKafkaListenerContainerFactory<Object, Object>();
        configurer.configure(factory, kafkaConsumerFactory);
        return factory;
    }

    @EnableKafka
    @ConditionalOnMissingBean(name = KafkaListenerConfigUtils.KAFKA_LISTENER_ANNOTATION_PROCESSOR_BEAN_NAME)
    protected static class EnableKafkaConfiguration {

    }
}

• ConcurrentKafkaListenerContainerFactoryConfigurer
  spring-boot-autoconfigure-1.5.7.RELEASE-sources.jar!/org/springframework/boot/autoconfigure/kafka/ConcurrentKafkaListenerContainerFactoryConfigurer.java

public class ConcurrentKafkaListenerContainerFactoryConfigurer {

    private KafkaProperties properties;

    /**
     * Set the {@link KafkaProperties} to use.
     * @param properties the properties
     */
    void setKafkaProperties(KafkaProperties properties) {
        this.properties = properties;
    }

    /**
     * Configure the specified Kafka listener container factory. The factory can be
     * further tuned and default settings can be overridden.
     * @param listenerContainerFactory the {@link ConcurrentKafkaListenerContainerFactory}
     * instance to configure
     * @param consumerFactory the {@link ConsumerFactory} to use
     */
    public void configure(
            ConcurrentKafkaListenerContainerFactory<Object, Object> listenerContainerFactory,
            ConsumerFactory<Object, Object> consumerFactory) {
        listenerContainerFactory.setConsumerFactory(consumerFactory);
        Listener container = this.properties.getListener();
        ContainerProperties containerProperties = listenerContainerFactory
                .getContainerProperties();
        if (container.getAckMode() != null) {
            containerProperties.setAckMode(container.getAckMode());
        }
        if (container.getAckCount() != null) {
            containerProperties.setAckCount(container.getAckCount());
        }
        if (container.getAckTime() != null) {
            containerProperties.setAckTime(container.getAckTime());
        }
        if (container.getPollTimeout() != null) {
            containerProperties.setPollTimeout(container.getPollTimeout());
        }
        if (container.getConcurrency() != null) {
            listenerContainerFactory.setConcurrency(container.getConcurrency());
        }
    }

}

创建并发的多个KafkaMessageListenerContainer，相当于一个应用实例创建多个consumer

如果是1.5版本及以上的springboot，使用起来就比较简单了，注入kafkaTemplate直接发消息，然后简单配置一下就可以消费消息

spring integration kafka

spring integration是spring关于Enterprise Integration Patterns的实现，而spring integration kafka则基于spring for apache kafka提供了inbound以及outbound channel的适配器
Starting from version 2.0 version this project is a complete rewrite based on the new spring-kafka project which uses the pure java Producer and Consumer clients provided by Kafka 0.9.x.x and 0.10.x.x

这个的话，没有自动配置，又引入了integration相关的概念，整体来讲，相对复杂一些。

consumer配置

    @Bean
    public KafkaMessageListenerContainer<String, String> container(
            ConsumerFactory<String, String> kafkaConsumerFactory) {
        return new KafkaMessageListenerContainer<>(kafkaConsumerFactory,
                new ContainerProperties(new TopicPartitionInitialOffset(topic, 0)));
    }

    /**
     * KAFKA consumer.
     */
    @Bean
    public ConsumerFactory<?, ?> kafkaConsumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, brokerAddress);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, consumerGroup);
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, true);
        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, 100);
        props.put(ConsumerConfig.SESSION_TIMEOUT_MS_CONFIG, 15000);
        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG,"earliest");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        return new DefaultKafkaConsumerFactory<>(props);
    }

    /**
     * Channel adapter for message.
     */
    @Bean
    public KafkaMessageDrivenChannelAdapter<String, String> adapter(KafkaMessageListenerContainer<String, String> container) {
        KafkaMessageDrivenChannelAdapter<String, String> kafkaMessageDrivenChannelAdapter =
                new KafkaMessageDrivenChannelAdapter<>(container);
        kafkaMessageDrivenChannelAdapter.setOutputChannel(fromKafka());
        return kafkaMessageDrivenChannelAdapter;
    }

    /**
     * Channel for KAFKA message received.
     */
    @Bean
    public PollableChannel fromKafka() {
        return new QueueChannel();
    }

producer配置

    @Bean
    @ServiceActivator(inputChannel = "toKafka")
    public MessageHandler handler() throws Exception {
        KafkaProducerMessageHandler<String, String> handler =
                new KafkaProducerMessageHandler<>(kafkaTemplate());
        handler.setTopicExpression(new LiteralExpression(topic));
        handler.setMessageKeyExpression(new LiteralExpression(messageKey));
        return handler;
    }

    @Bean
    public ProducerFactory<String, String> kafkaProducerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, brokerAddress);
        props.put(ProducerConfig.RETRIES_CONFIG, 0);
        props.put(ProducerConfig.BATCH_SIZE_CONFIG, 16384);
        props.put(ProducerConfig.LINGER_MS_CONFIG, 1);
        props.put(ProducerConfig.BUFFER_MEMORY_CONFIG, 33554432);
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        return new DefaultKafkaProducerFactory<>(props);
    }

    @Bean
    public KafkaTemplate<String, String> kafkaTemplate() {
        return new KafkaTemplate<>(kafkaProducerFactory());
    }

收发信息

    @Autowired
    @Qualifier("fromKafka")
    private PollableChannel fromKafka;

    @Autowired
    @Qualifier("toKafka")
    MessageChannel toKafka;

    Message msg = fromKafka.receive(10000l);
    toKafka.send(new GenericMessage<Object>(UUID.randomUUID().toString()));

spring cloud stream

基于Spring Integration构建，在spring cloud环境中又稍作加工，也稍微有点封装了.
具体详见spring cloud stream kafka实例以及spring-cloud-stream-binder-kafka属性配置

doc

• spring-kafka
• spring-integration
• spring-integration-kafka
• spring-integration-samples-kafka
• spring-cloud-stream
• spring boot与kafka集成
• 总结kafka的consumer消费能力很低的情况下的处理方案