Apache Kafka是一个开源项目,用于根据容错消息传递系统发布和订阅消息.它设计快速,可扩展和分布.如果您是Kafka的初学者,或想要更好地了解它,请参阅此链接 : www.it1352.com/apache_kafka/
在本章中,我们将看看如何在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.
<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'
要向Apache Kafka生成消息,我们需要为Producer配置定义Configuration类,如下所示 :
package com.it1352.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对象并生成消息,如图所示.
@Autowired private KafkaTemplate<String, String> kafkaTemplate; public void sendMessage(String msg) { kafkaTemplate.send(topicName, msg); }
要使用消息,我们需要编写Consumer配置类文件如下所示.
package com.it1352.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,编写一个监听器来收听消息.
@KafkaListener(topics ="it1352",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应用程序类文件中调用ApplicationRunner类run方法的sendMessage()方法,并使用来自相同的类文件.
您的主要Spring Boot应用程序类文件代码在下面和下面给出;
package com.it1352.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("it1352", msg); } public static void main(String[] args) { SpringApplication.run(KafkaDemoApplication.class, args); } @KafkaListener(topics = "it1352", 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"); } }
完整构建配置文件的代码如下所示.
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.IT屋</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.it1352' 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JA R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.
使用运行JAR文件这里给出的命令 :
java -jar <JARFILE>
您可以在控制台窗口中看到输出.