spring整合kafka如何實現消息分發

在Spring中整合Kafka以實現消息分發，你需要遵循以下步驟：

1. 添加依賴

在你的項目中，添加Spring Boot Kafka的依賴。在Maven項目的pom.xml文件中添加以下依賴：

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

2. 配置Kafka

在application.properties或application.yml文件中，配置Kafka相關的屬性，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

3. 創建Kafka配置類

創建一個Kafka配置類，用于設置Kafka的生產者和消費者模板。

@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;
    }
}

4. 創建消息監聽器

創建一個消息監聽器類，用于處理接收到的消息。這個類需要實現ConsumerAwareErrorHandler接口，以便在發生錯誤時進行處理。

@Service
public class MyKafkaListener implements ConsumerAwareErrorHandler {

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

5. 創建Kafka消息處理器

創建一個類，用于處理接收到的消息。這個類需要實現MessageListener接口。

public class MyKafkaMessageListener implements MessageListener {

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

6. 創建Kafka消息分發器

創建一個類，用于分發消息。這個類需要注入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);
            }
        });
    }
}

7. 在主應用中啟動Kafka監聽

在你的主應用類中，注入KafkaMessageDistributor并啟動Kafka監聽。

@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");
    }
}

現在，當你的應用程序接收到發送到my-topic主題的消息時，MyKafkaMessageListener將處理這些消息。你可以根據需要修改這些類以實現自定義的消息分發邏輯。