Apache Kafka是一个开源项目,用于基于容错消息系统发布和订阅消息。它是快速,可伸缩的。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.learnfk.com/apache_kafka/
在本章中,无涯教程将了解如何在Spring Boot应用程序中实现Apache Kafka。
首先,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。
<dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId> <version>2.1.0.RELEASE</version> </dependency>
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,需要为Producer配置定义Configuration类,如下所示:
package com.learnfk.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<String, String> producerFactory() { Map<String, Object> 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<String, String> 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<String, String> kafkaTemplate; public void sendMessage(String msg) { kafkaTemplate.send(topicName, msg); }
要使用消息,需要编写一个Consumer配置类文件,如下所示。
package com.learnfk.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<String, String> consumerFactory() { Map<String, Object> 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<String, String> kafkaListenerContainerFactory() { ConcurrentKafkaListenerContainerFactory<String, String> factory=new ConcurrentKafkaListenerContainerFactory<>(); factory.setConsumerFactory(consumerFactory()); return factory; } }
接下来,编写一个监听器来监听消息。
链接:https://www.learnfk.comhttps://www.learnfk.com/spring-boot/spring-boot-apache-kafka.html
来源:LearnFk无涯教程网
@KafkaListener(topics="learnfk", groupId="group-id") public void listen(String message) { System.out.println("Received Messasge in group - group-id: " + message); }
让无涯教程从主Spring Boot应用程序类文件的ApplicationRunner类run方法调用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.learnfk.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<String, String> kafkaTemplate; public void sendMessage(String msg) { kafkaTemplate.send("learnfk", msg); } public static void main(String[] args) { SpringApplication.run(KafkaDemoApplication.class, args); } @KafkaListener(topics="learnfk", 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
<?xml version="1.0" encoding="UTF-8"?> <project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.learnfk</groupId> <artifactId>kafka-demo</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>kafka-demo</name> <description>Demo project for Spring Boot</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.9.RELEASE</version> <relativePath /> <!-- lookup parent from repository --> </parent> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding> <java.version>1.8</java.version> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.springframework.kafka</groupId> <artifactId>spring-kafka</artifactId> <version>2.1.0.RELEASE</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
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.learnfk' 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 <JARFILE>
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