spring整合kafka如何实现消息分发

在Spring中整合Kafka以实现消息分发，你需要遵循以下步骤：

添加依赖

在你的项目中，添加Spring Boot Kafka的依赖。在Maven项目的pom.xml文件中添加以下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-kafka</artifactId>
</dependency>

配置Kafka

在application.properties或application.yml文件中，配置Kafka相关的属性，例如：

# application.properties
spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.group-id=my-group
spring.kafka.consumer.auto-offset-reset=earliest
spring.kafka.consumer.key-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.value-deserializer=org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer=org.apache.kafka.common.serialization.StringSerializer

创建Kafka配置类

创建一个Kafka配置类，用于设置Kafka的生产者和消费者模板。

@Configuration
public class KafkaConfig {

    @Value("${spring.kafka.bootstrap-servers}")
    private String bootstrapServers;

    @Bean
    public ProducerFactory<String, String> producerFactory() {
        Map<String, Object> configProps = new HashMap<>();
        configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        return new DefaultKafkaProducerFactory<>(configProps);
    }

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

    @Bean
    public ConsumerFactory<String, String> consumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "my-group");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
        return new DefaultKafkaConsumerFactory<>(props);
    }

    @Bean
    public ConcurrentKafkaListenerContainerFactory<String, String> kafkaListenerContainerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, String> factory = new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(consumerFactory());
        return factory;
    }
}

创建消息监听器

创建一个消息监听器类，用于处理接收到的消息。这个类需要实现ConsumerAwareErrorHandler接口，以便在发生错误时进行处理。

@Service
public class MyKafkaListener implements ConsumerAwareErrorHandler {

    @Override
    public void handle(Exception thrownException, ConsumerRecord<?, ?> data) {
        System.out.println("Error occurred while processing message: " + thrownException.getMessage());
    }
}

创建Kafka消息处理器

创建一个类，用于处理接收到的消息。这个类需要实现MessageListener接口。

public class MyKafkaMessageListener implements MessageListener {

    @Override
    public void onMessage(ConsumerRecord<?, ?> record) {
        System.out.println("Received message: " + record.value());
    }
}

创建Kafka消息分发器

创建一个类，用于分发消息。这个类需要注入KafkaTemplate和MyKafkaMessageListener。

@Service
public class KafkaMessageDistributor {

    @Autowired
    private KafkaTemplate<String, String> kafkaTemplate;

    @Autowired
    private MyKafkaMessageListener myKafkaMessageListener;

    public void distributeMessage(String topic, String message) {
        kafkaTemplate.send(topic, message);
    }

    public void startListening(String topic) {
        kafkaTemplate.execute(new KafkaCallback<String, String>() {
            @Override
            public void doWithKafka(String topic, ConsumerRecord<String, String> data) {
                myKafkaMessageListener.onMessage(data);
            }
        });
    }
}

在主应用中启动Kafka监听

在你的主应用类中，注入KafkaMessageDistributor并启动Kafka监听。

@SpringBootApplication
public class KafkaApplication {

    public static void main(String[] args) {
        SpringApplication.run(KafkaApplication.class, args);
    }

    @Autowired
    private KafkaMessageDistributor kafkaMessageDistributor;

    @PostConstruct
    public void startKafkaListener() {
        kafkaMessageDistributor.startListening("my-topic");
    }
}

现在，当你的应用程序接收到发送到my-topic主题的消息时，MyKafkaMessageListener将处理这些消息。你可以根据需要修改这些类以实现自定义的消息分发逻辑。

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