Kafka श्रोता कंटेनर बनाना

package com.example.kafkaconsumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.EnableKafka;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

@SpringBootApplication
@EnableKafka
public class KafkaConsumerApplication {
  public static void main(String[] args) {
    // In a real app, SpringApplication.run() starts the context
    // and registers the @KafkaListener methods.
    System.out.println("Spring Boot Kafka Consumer App Started (simulated)");
    // For a runnable snippet, we just show the listener logic.
    // In a full app, this would run indefinitely, waiting for messages.
  }
}

@Component
class MyStringListener {
  @KafkaListener(topics = "my-topic", groupId = "my-group")
  public void listen(String message) {
    System.out.println("Received String: " + message);
  }
}

package com.example.kafkaconsumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.EnableKafka;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

@SpringBootApplication
@EnableKafka
public class KafkaConsumerApplication {
  public static void main(String[] args) {
    System.out.println("Spring Boot Kafka Consumer App Started (simulated)");
  }
}

@Component
class MultiTopicListener {
  @KafkaListener(topics = {"topic-a", "topic-b"}, groupId = "multi-group")
  public void listenMultipleTopics(String message) {
    System.out.println("Received from multiple topics: " + message);
  }
}

package com.example.kafkaconsumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.EnableKafka;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;

// A simple data class representing an event
class MyEvent {
  private String id;
  private String description;

  // Getters and setters are essential for deserialization
  public String getId() { return id; }
  public void setId(String id) { this.id = id; }
  public String getDescription() { return description; }
  public void setDescription(String description) { this.description = description; }

  @Override
  public String toString() {
    return "MyEvent{id='" + id + "', description='" + description + "'}";
  }
}

@SpringBootApplication
@EnableKafka
public class KafkaConsumerApplication {
  public static void main(String[] args) {
    System.out.println("Spring Boot Kafka Consumer App Started (simulated)");
  }
}

@Component
class MyObjectListener {
  @KafkaListener(topics = "object-topic", groupId = "object-group")
  public void listenObject(MyEvent event) {
    System.out.println("Received object: " + event);
  }
}

package com.example.kafkaconsumer;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.EnableKafka;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.messaging.handler.annotation.Header;
import org.springframework.messaging.handler.annotation.Payload;
import org.springframework.stereotype.Component;

@SpringBootApplication
@EnableKafka
public class KafkaConsumerApplication {
  public static void main(String[] args) {
    System.out.println("Spring Boot Kafka Consumer App Started (simulated)");
  }
}

@Component
class MyMetadataListener {
  @KafkaListener(topics = "metadata-topic", groupId = "meta-group")
  public void listenWithMetadata(
      @Payload String message,
      @Header("kafka_receivedTopic") String topic,
      @Header("kafka_receivedPartitionId") int partition,
      @Header("kafka_offset") long offset) {
    System.out.println("Topic: " + topic + ", Partition: " + partition + ", Offset: " + offset);
    System.out.println("Message: " + message);
  }
}