Spring Boot Kafka Producer and Consumer Example

You need to start with following read

https://medium.com/@ergulcu/kafka-with-kafkaui-to-test-kafka-listener-localy-65e3d556854b

or start kafka broker on localhost:9092

creating message producer project with spring initializer

add properties to application.properties file

add service

package com.ergulcu.kafkaproducer.service;

public interface MessageService {
    void sendMessage(String message);
}

add service impl

@Service
@RequiredArgsConstructor
public class MessageServiceImpl implements MessageService {
    private final KafkaTemplate<String, String> kafkaTemplate;
    @Override
    public void sendMessage(String message){
        kafkaTemplate.send("TestTopic", message);
    }

}

add controller

package com.ergulcu.kafkaproducer.controller;

import com.ergulcu.kafkaproducer.service.MessageService;
import lombok.RequiredArgsConstructor;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequiredArgsConstructor
public class MessageController {
    private final MessageService messageService;
    @PostMapping("/message")
    public void postMessage(@RequestBody String message){
        messageService.sendMessage(message);
    }
}

creating message consumer project with spring initializer

add properties to application.properties file

server.port=8788
spring.application.name=kafkaproducer
spring.kafka.bootstrap-servers=localhost:9092
spring.kafka.consumer.group-id=myGroup

add service

package com.ergulcu.kafkaconsumer.service;

public interface MessageService {
}

add service impl

package com.ergulcu.kafkaconsumer.service.impl;

import com.ergulcu.kafkaconsumer.service.MessageService;
import lombok.RequiredArgsConstructor;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Service;

@Service
@RequiredArgsConstructor
public class MessageServiceImpl implements MessageService {
    @KafkaListener(topics = "TestTopic",groupId = "TestGroup")
    public void listenGroupFoo(String message) {
        System.out.println("Received Message from TestTopic:" + message);
    }

}

send message to producer with postman

endpoint: localhost:8787/message

request body: testing message {{$randomWord}} {{$isoTimestamp}}

see messages on consumer console

ready to run projects if you want to try directly

https://github.com/ergulcu/kafkaconsumer

https://github.com/ergulcu/kafkaproducer