<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="https://maven.apache.org/POM/4.0.0" xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="https://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <parent>
     <groupId>org.springframework.boot</groupId>
     <artifactId>spring-boot-starter-parent</artifactId>
     <version>2.1.6.RELEASE</version>
     <relativePath/> <!-- lookup parent from repository, not local -->
  </parent>
  <groupId>com.example</groupId>
  <artifactId>KafkaProducer</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <name>KafkaProducer</name>
  <description>Kafka Producer Demo Project</description>
  <properties>
     <java.version>11</java.version>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
     <spring-boot.version>2.1.6.RELEASE</spring-boot.version>
  </properties>
  <dependencies>
     <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter</artifactId>
     </dependency>
     <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
     </dependency>
     <dependency>
        <groupId>org.springframework.kafka</groupId>
        <artifactId>spring-kafka</artifactId>
     </dependency>

     <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
     </dependency>
  </dependencies>
  <dependencyManagement>
     <dependencies>
        <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-dependencies</artifactId>
           <version>${spring-boot.version}</version>
           <type>pom</type>
           <scope>import</scope>
        </dependency>
     </dependencies>
  </dependencyManagement>

  <build>
     <plugins>
        <plugin>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-maven-plugin</artifactId>
           <version>${spring-boot.version}</version>
           <executions>
              <execution>
                 <id>build-info</id>
                 <goals>
                    <goal>build-info</goal>
                    <goal>repackage</goal>
                 </goals>
              </execution>
           </executions>
        </plugin>
     </plugins>
  </build>
  <repositories>
     <repository>
        <id>mdcm</id>
        <name>mdcm</name>
        <url>https://nexuscimgmt.sgp.dbs.com:8443/nexus/content/repositories/MDCM</url>
        <snapshots>
           <enabled>false</enabled>
        </snapshots>
     </repository>
  </repositories>
  <pluginRepositories>
     <pluginRepository>
        <id>mdcm</id>
        <name>mdcm</name>
        <url>https://nexuscimgmt.sgp.dbs.com:8443/nexus/content/repositories/MDCM</url>
        <snapshots>
           <enabled>false</enabled>
        </snapshots>
     </pluginRepository>
  </pluginRepositories>

</project>

spring.kafka.producer.bootstrap-servers: localhost:9092
spring.kafka.producer.key-serializer: org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.value-serializer: org.apache.kafka.common.serialization.StringSerializer

package com.java4coding.kafka;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.stereotype.Service;

@Service
public class KafkaProducer {

   private static final Logger LOGGER = LoggerFactory.getLogger(KafkaProducer.class);

   @Autowired
   private KafkaTemplate<String, String> kafkaTemplate;

   public void sendMessage(String message) {
       LOGGER.info(String.format("Message sent -> %s", message));
       kafkaTemplate.send("demotopic", message);
   }
}

package com.java4coding.restcontroller;

import com.java4coding.kafka.KafkaProducer;

import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

@RestController
public class KafkaProducerController {

   private KafkaProducer kafkaProducer;

   public KafkaProducerController(KafkaProducer kafkaProducer) {
       this.kafkaProducer = kafkaProducer;
   }

   @GetMapping("/publish")
   public ResponseEntity<String> publish(@RequestParam("message") String message) {
       kafkaProducer.sendMessage(message);
       return ResponseEntity.ok("Message sent to kafka topic");
   }
}

package com.java4coding.main;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.context.annotation.ComponentScan;

@SpringBootApplication
@ComponentScan("com.java4coding")
public class DemoProducerApplication {

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

}