📅  最后修改于: 2020-11-11 05:53:09             🧑  作者: Mango
Apache Kafka是一个开源项目,用于基于容错消息传递系统发布和订阅消息。它是快速,可扩展的,并且可以按设计进行分发。如果您是Kafka的初学者,或者想对它有所了解,请参阅此链接-www.tutorialspoint.com/apache_kafka/
在本章中,我们将看到如何在Spring Boot应用程序中实现Apache Kafka。
首先,我们需要在构建配置文件中添加Spring Kafka依赖项。
Maven用户可以在pom.xml文件中添加以下依赖项。
org.springframework.kafka
spring-kafka
2.1.0.RELEASE
Gradle用户可以在build.gradle文件中添加以下依赖项。
compile group: 'org.springframework.kafka', name: 'spring-kafka', version: '2.1.0.RELEASE'
要将消息生成到Apache Kafka中,我们需要为Producer配置定义Configuration类,如下所示:
package com.tutorialspoint.kafkademo;
import java.util.HashMap;
import java.util.Map;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.common.serialization.StringSerializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.core.DefaultKafkaProducerFactory;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.core.ProducerFactory;
@Configuration
public class KafkaProducerConfig {
@Bean
public ProducerFactory producerFactory() {
Map configProps = new HashMap<>();
configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:9092");
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 kafkaTemplate() {
return new KafkaTemplate<>(producerFactory());
}
}
要发布消息,请自动连接Kafka Template对象并产生消息,如图所示。
@Autowired
private KafkaTemplate kafkaTemplate;
public void sendMessage(String msg) {
kafkaTemplate.send(topicName, msg);
}
要使用消息,我们需要编写一个Consumer配置类文件,如下所示。
package com.tutorialspoint.kafkademo;
import java.util.HashMap;
import java.util.Map;
import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.annotation.EnableKafka;
import org.springframework.kafka.config.ConcurrentKafkaListenerContainerFactory;
import org.springframework.kafka.core.ConsumerFactory;
import org.springframework.kafka.core.DefaultKafkaConsumerFactory;
@EnableKafka
@Configuration
public class KafkaConsumerConfig {
@Bean
public ConsumerFactory consumerFactory() {
Map props = new HashMap<>();
props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "localhost:2181");
props.put(ConsumerConfig.GROUP_ID_CONFIG, "group-id");
props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
return new DefaultKafkaConsumerFactory<>(props);
}
@Bean
public ConcurrentKafkaListenerContainerFactory kafkaListenerContainerFactory() {
ConcurrentKafkaListenerContainerFactory
factory = new ConcurrentKafkaListenerContainerFactory<>();
factory.setConsumerFactory(consumerFactory());
return factory;
}
}
接下来,编写一个监听器来监听消息。
@KafkaListener(topics = "tutorialspoint", groupId = "group-id")
public void listen(String message) {
System.out.println("Received Messasge in group - group-id: " + message);
}
让我们从主Spring Boot应用程序类文件的ApplicationRunner类run方法中调用sendMessage()方法,并使用同一类文件中的消息。
您的主要Spring Boot应用程序类文件代码如下所示-
package com.tutorialspoint.kafkademo;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.kafka.core.KafkaTemplate;
@SpringBootApplication
public class KafkaDemoApplication implements ApplicationRunner {
@Autowired
private KafkaTemplate kafkaTemplate;
public void sendMessage(String msg) {
kafkaTemplate.send("tutorialspoint", msg);
}
public static void main(String[] args) {
SpringApplication.run(KafkaDemoApplication.class, args);
}
@KafkaListener(topics = "tutorialspoint", groupId = "group-id")
public void listen(String message) {
System.out.println("Received Messasge in group - group-id: " + message);
}
@Override
public void run(ApplicationArguments args) throws Exception {
sendMessage("Hi Welcome to Spring For Apache Kafka");
}
}
完整的构建配置文件的代码如下。
Maven – pom.xml
4.0.0
com.tutorialspoint
kafka-demo
0.0.1-SNAPSHOT
jar
kafka-demo
Demo project for Spring Boot
org.springframework.boot
spring-boot-starter-parent
1.5.9.RELEASE
UTF-8
UTF-8
1.8
org.springframework.boot
spring-boot-starter
org.springframework.kafka
spring-kafka
2.1.0.RELEASE
org.springframework.boot
spring-boot-starter-test
test
org.springframework.boot
spring-boot-maven-plugin
Gradle – build.gradle
buildscript {
ext {
springBootVersion = '1.5.9.RELEASE'
}
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:${springBootVersion}")
}
}
apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'org.springframework.boot'
group = 'com.tutorialspoint'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = 1.8
repositories {
mavenCentral()
}
dependencies {
compile('org.springframework.boot:spring-boot-starter')
compile group: 'org.springframework.kafka', name: 'spring-kafka', version: '2.1.0.RELEASE'
testCompile('org.springframework.boot:spring-boot-starter-test')
}
现在,创建一个可执行的JAR文件,并使用下面的Maven或Gradle命令运行Spring Boot应用程序,如下所示-
对于Maven,使用如下所示的命令-
mvn clean install
在“ BUILD SUCCESS”之后,您可以在目标目录下找到JAR文件。
对于Gradle,使用如下所示的命令-
gradle clean build
在“ BUILD SUCCESSFUL”之后,您可以在build / libs目录下找到JAR文件。
使用此处给定的命令运行JAR文件-
java –jar
您可以在控制台窗口中看到输出。