Spring Cloud - 8 (Spring Cloud Stream)
荆树
Spring Cloud Stream
Kafka
官方网页
主要用途
- 消息中间件
- 流式计算处理
- 日志
下载地址：Apache Kafka
执行脚本目录 /bin
windows 在其单独的目录
快速上手
下载并且解压kafka压缩包
运行服务
以Windows为例，首先打开cmd：
1. 启动zookeeper：
bin\windows\zookeeper-server-start.bat config\zookeeper.properties2. 启动kafka：
bin\windows\kafka-server-start.bat config\server.properties创建主题topic
bin\windows\kafka-topics.bat --create --bootstrap-server localhost:9092 --replication-factor 1 --partitions 1 --topic cloudcloud
生产者：发送消息
\bin\windows>kafka-console-producer.bat --broker-list localhost:9092 --topic cloud
>hello消费者：接收消息
\bin\windows>kafka-console-consumer.bat --bootstrap-server localhost:9092 --topic cloud --from-beginning
hello同类产品比较
- ActiveMQ：JMS（Java Message Service）规范实现
- RabbitMQ：AMQP（Advanced Message Queue Protocol）规范实现
- Kafka：并非某种规范实现，它的灵活和性能相对是优势
Spring Kafka
import java.util.Properties;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.apache.kafka.common.serialization.StringSerializer;
public class TestKafka {
public static void main(String[] args) throws ExecutionException, InterruptedException {
Properties properties = new Properties();
properties.setProperty("bootstrap.servers", "localhost:9092");
properties.setProperty("key.serializer", StringSerializer.class.getName());
properties.setProperty("value.serializer", StringSerializer.class.getName());
// 创建 Kafka Producer
KafkaProducer<String, String> kafkaProducer = new KafkaProducer(properties);
// 创建Kafka消息 = ProducerRecord
String topic = "cloud";
Integer partition = 0;
Long timestamp = System.currentTimeMillis();
String key = "message-key";
String value = "how are you!";
ProducerRecord<String, String> record = new ProducerRecord<String, String>(topic, partition, timestamp, key, value);
// 发送kafka消息
Future<RecordMetadata> metadataFuture = kafkaProducer.send(record);
// 强制执行
metadataFuture.get();
}
}
设计模式
Spring社区对data（Spring-data）操作，有一个基本的模式，Template模式：
- JDBC：JdbcTemplate
- Redis：RedisTemplate
- Kafka：KafkaTemplate
- JMS：JmsTemplate
- Rest：RestTemplate
XXXTemplate一定实现XXXOpeations
KafkaTemplate implements KafkaOpeations
Maven依赖
<dependency>
<groupId>org.springframework.kafka</groupId>
<artifactId>spring-kafka</artifactId>
</dependency>自动装配器： KafkaAutoConfiguration
其中KafkaTemplate会被自动装配：
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.kafka.KafkaProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.kafka.core.ProducerFactory;
import org.springframework.kafka.support.ProducerListener;
@Configuration
public class KafkaAutoConfiguration {
private final KafkaProperties properties;
public KafkaAutoConfiguration(KafkaProperties properties) {
this.properties = properties;
}
@Bean
@ConditionalOnMissingBean(KafkaTemplate.class)
public KafkaTemplate<?,?> kafkaTemplate(ProducerFactory<Object,Object> kafkaProducerFactory,
ProducerListener<Object,Object> kafkaProducerListener){
KafkaTemplate<Object,Object> kafkaTemplate = new KafkaTemplate<Object,Object>(kafkaProducerFactory);
kafkaTemplate.setProducerListener(kafkaProducerListener);
kafkaTemplate.setDefaultTopic(this.properties.getTemplate().getDefaultTopic());
return kafkaTemplate;
}
}创建生产者
增加生产者配置
application.properties
全局配置：
### Kafka生产者配置
spring.kafka.producer.bootstrapServers = localhost:9092
### Kafka生产者配置
# spring.kafka.producer.bootstrapServers = localhost:9092
spring.kafka.producer.keySerializer = org.apache.kafka.common.serialization.StringSerializer
spring.kafka.producer.valueSerializer = org.apache.kafka.common.serialization.StringSerializerimport org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class KafkaProducerController {
private final KafkaTemplate<String, String> kafkaTemplate;
private final String topic;
@Autowired
public KafkaProducerController(KafkaTemplate<String, String> kafkaTemplate, @Value("${kafka.topic}") String topic) {
this.kafkaTemplate = kafkaTemplate;
this.topic = topic;
}
@PostMapping("/message/send")
public Boolean sendMessage(@RequestParam(required=false)String message) {
kafkaTemplate.send(topic, message);
return true;
}
}创建消费者
增加消费者配置
### Kafka消费者配置
spring.kafka.consumer.groupId = cloud-1
spring.kafka.consumer.keyDeserializer = org.apache.kafka.common.serialization.StringDeserializer
spring.kafka.consumer.valueDeserializer = org.apache.kafka.common.serialization.StringDeserializerimport org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Component;
@Component
public class KafkaConsumerListener {
@KafkaListener(topics = "${kafka.topic}")
public void onMessage(String message) {
System.out.print("kafka 消费者监听器，接收到消息：" + message);
}
}Spring Cloud Stream
基本概念
- Source：来源，近义词：Producer、Publisher
- Sink：接收器，近义词：Consumer、Subscriber
- Processor：对于上流而言是Sink，对于下流而言是Source
Reactive Streams：
- Publisher
- Subscriber
- Processor
Spring Cloud Stream Binder:kafka
定义标准消息发送源
@Component
@EnableBinding(Source.class)
public class MessageProducerBean {
@Autowired
@Qualifier(Source.OUTPUT)
private MessageChannel messageChannel;
@Autowired
private Source source;
public void send(String message) {
messageChannel.send(MessageBuilder.withPayload(message).build());
source.output().send(MessageBuilder.withPayload(message).build());
}
}注入
@RestController
public class KafkaProducerController {
private final KafkaTemplate<String, String> kafkaTemplate;
private final MessageProducerBean messageProducerBean;
private final String topic;
@Autowired
public KafkaProducerController(KafkaTemplate<String, String> kafkaTemplate,
@Value("${kafka.topic}") String topic,
MessageProducerBean messageProducerBean) {
this.kafkaTemplate = kafkaTemplate;
this.messageProducerBean = messageProducerBean;
this.topic = topic;
}
@PostMapping("/message/send")
public Boolean sendMessage(@RequestParam(required=false)String message) {
kafkaTemplate.send(topic, message);
return true;
}
@GetMapping("/message/output/send")
public Boolean outputSend(@RequestParam String message) {
messageProducerBean.send(message);
return true;
}
}实现标准Sink监听
@Component
@EnableBinding(Sink.class)
public class MessageConsumerBean {
@Autowired
@Qualifier(Sink.INPUT)
private SubscribableChannel subscribableChannel;
@Autowired
private Sink sink;
@PostConstruct
public void init() {
subscribableChannel.subscribe(new MessageHandler() {
@Override
public void handleMessage(Message<?> message) throws MessagingException {
System.out.println("init: "+message.getPayload());
}
});
}
@ServiceActivator(inputChannel = Sink.INPUT)
public void serviceActivator(Object message) {
System.out.println("serviceActivator: "+message);
}
@StreamListener(Sink.INPUT)
public void streamListener(String message) {
System.out.println("streamListener: "+message);
}
}自定义标准消息发送源
public interface MySource {
String MYOUTPUT = "myoutput";
@Output(MySource.MYOUTPUT)
MessageChannel myoutput();
}@Component
@EnableBinding(MySource.class)
public class MyMessageProducerBean {
@Autowired
@Qualifier(MySource.MYOUTPUT)
private MessageChannel messageChannel;
@Autowired
private MySource mySource;
public void send(String message) {
messageChannel.send(MessageBuilder.withPayload(message).build());
mySource.myoutput().send(MessageBuilder.withPayload(message).build());
}
}自定义Sink监听
public interface MySink {
String MYINPUT = "myinput";
@Input(MySink.MYINPUT)
SubscribableChannel input();
}@Component
@EnableBinding(MySink.class)
public class MyMessageConsumerBean {
@Autowired
@Qualifier(MySink.MYINPUT)
private SubscribableChannel subscribableChannel;
@Autowired
private MySink mySink;
@PostConstruct
public void init() {
subscribableChannel.subscribe(new MessageHandler() {
@Override
public void handleMessage(Message<?> message) throws MessagingException {
System.out.println("my - Sink: "+message.getPayload());
}
});
}
@ServiceActivator(inputChannel = MySink.MYINPUT)
public void serviceActivator(Object message) {
System.out.println("my - serviceActivator: "+message);
}
@StreamListener(MySink.MYINPUT)
public void streamListener(String message) {
System.out.println("my - streamListener: "+message);
}
}配置项
kafka.topic.my = mytopic
spring.cloud.stream.bindings.myoutput.destination=${kafka.topic.my}
spring.cloud.stream.bindings.myinput.destination=${kafka.topic.my}Spring Cloud Stream Binder:rabbit
重构Kafka工程，删除强依赖
Stream-kafka实现源码：https://pan.baidu.com/s/1RX5W2wMj4h_SKDkjlPQHkA 提取码：lwak
Stream-rabbit实现源码：https://pan.baidu.com/s/1AX6asvmATN9-dYrhIIfS7w 提取码：dsc5
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