Apache Kafka is a distributed event streaming platform that facilitates real-time data processing. This guide demonstrates how to send and consume JSON messages in a Spring Boot application using Kafka.
Apache Kafka is a distributed event streaming platform that facilitates real-time data processing. This guide demonstrates how to send and consume JSON messages in a Spring Boot application using Kafka.
In this section, we clarify Why Use Kafka? and summarize the key points you will apply in implementation.
🕊 Ensure you have the following:
To integrate Kafka into your Spring Boot project, add the following dependencies:
<dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId> </dependency>
implementation 'org.springframework.kafka:spring-kafka'
Set up Kafka connection in your application.properties or application.yml file:
spring.kafka.bootstrap-servers=localhost:9092 spring.kafka.consumer.group-id=my-group spring.kafka.consumer.auto-offset-reset=earliest spring.kafka.producer.key-serializer=org.apache.kafka.common.serialization.StringSerializer spring.kafka.producer.value-serializer=org.springframework.kafka.support.serializer.JsonSerializer spring.kafka.consumer.value-deserializer=org.springframework.kafka.support.serializer.JsonDeserializer spring.kafka.consumer.properties.spring.json.trusted.packages=*
In this section, we clarify Step 3: Create a Model for JSON Messages and summarize the key points you will apply in implementation.
This model defines the message contract shared across producer, consumer, and controller layers.
In this section, we clarify Step 4: Implement Kafka Producer and Consumer and summarize the key points you will apply in implementation.
This producer example shows how to publish messages consistently to the target topic.
This consumer example demonstrates how incoming messages are read and processed.
This controller exposes a simple endpoint so you can trigger and verify messaging behavior.
Run the application using the following command:
./mvnw spring-boot:run
You can test the Kafka Producer endpoint using cURL or Postman:
curl -X POST "http://localhost:8080/kafka/publish" \ -H "Content-Type: application/json" \ -d '{"id": "123", "content": "Hello Kafka!"}'
You now have a practical Spring Boot Kafka Integration implementation with a clear, production-friendly Spring Boot structure. As a next step, adapt configuration and tests to your own domain, then validate behavior under realistic traffic and failure scenarios.
package com.example.kafka.model; import lombok.AllArgsConstructor; import lombok.Data; import lombok.NoArgsConstructor; @Data @NoArgsConstructor @AllArgsConstructor public class Message { private String id; private String content; }
package com.example.kafka.model data class Message( val id: String, val content: String )
package com.example.kafka.producer; import com.example.kafka.model.Message; import lombok.RequiredArgsConstructor; import org.springframework.kafka.core.KafkaTemplate; import org.springframework.stereotype.Service; @Service @RequiredArgsConstructor public class KafkaProducer { private final KafkaTemplate<String, Message> kafkaTemplate; public void sendMessage(String topic, Message message) { kafkaTemplate.send(topic, message); } }
package com.example.kafka.producer import com.example.kafka.model.Message import org.springframework.kafka.core.KafkaTemplate import org.springframework.stereotype.Service @Service class KafkaProducer(private val kafkaTemplate: KafkaTemplate<String, Message>) { fun sendMessage(topic: String, message: Message) { kafkaTemplate.send(topic, message) } }
package com.example.kafka.consumer; import com.example.kafka.model.Message; import org.springframework.kafka.annotation.KafkaListener; import org.springframework.stereotype.Service; @Service public class KafkaConsumer { @KafkaListener(topics = "my-topic", groupId = "my-group") public void consumeMessage(Message message) { System.out.println("Received message: " + message); } }
package com.example.kafka.consumer import com.example.kafka.model.Message import org.springframework.kafka.annotation.KafkaListener import org.springframework.stereotype.Service @Service class KafkaConsumer { @KafkaListener(topics = ["my-topic"], groupId = "my-group") fun consumeMessage(message: Message) { println("Received message: $message") } }
package com.example.kafka.controller; import com.example.kafka.model.Message; import com.example.kafka.producer.KafkaProducer; import lombok.RequiredArgsConstructor; import org.springframework.web.bind.annotation.*; @RestController @RequestMapping("/kafka") @RequiredArgsConstructor public class KafkaController { private final KafkaProducer kafkaProducer; @PostMapping("/publish") public String publishMessage(@RequestParam String topic, @RequestBody Message message) { kafkaProducer.sendMessage(topic, message); return "Message sent to topic: " + topic; } }
package com.example.kafka.controller import com.example.kafka.model.Message import com.example.kafka.producer.KafkaProducer import org.springframework.web.bind.annotation.* @RestController @RequestMapping("/kafka") class KafkaController(private val kafkaProducer: KafkaProducer) { @PostMapping("/publish") fun publishMessage(@RequestParam topic: String, @RequestBody message: Message): String { kafkaProducer.sendMessage(topic, message) return "Message sent to topic: $topic" } }
