1、在kafka-demo中创建配置类
配置kafka参数
package com.heima.kafkademo.config;
import lombok.Data;
import org.apache.kafka.common.serialization.Serdes;
import org.apache.kafka.streams.StreamsConfig;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.kafka.annotation.EnableKafkaStreams;
import org.springframework.kafka.annotation.KafkaStreamsDefaultConfiguration;
import org.springframework.kafka.config.KafkaStreamsConfiguration;
import java.util.HashMap;
import java.util.Map;
/**
* 通过重新注册KafkaStreamsConfiguration对象,设置自定配置参数
*/
@Data
@Configuration
@EnableKafkaStreams
@ConfigurationProperties(prefix="kafka")
public class KafkaStreamConfig {
private static final int MAX_MESSAGE_SIZE = 16* 1024 * 1024;
private String hosts;
private String group;
@Bean(name = KafkaStreamsDefaultConfiguration.DEFAULT_STREAMS_CONFIG_BEAN_NAME)
public KafkaStreamsConfiguration defaultKafkaStreamsConfig() {
Map<String, Object> props = new HashMap<>();
props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, hosts);
props.put(StreamsConfig.APPLICATION_ID_CONFIG, this.getGroup()+"_stream_aid");
props.put(StreamsConfig.CLIENT_ID_CONFIG, this.getGroup()+"_stream_cid");
props.put(StreamsConfig.RETRIES_CONFIG, 10);
props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass());
props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass());
return new KafkaStreamsConfiguration(props);
}
}
2、在application.yml中配置上面配置类需要的参数
server:
port: 9991
spring:
application:
name: kafka-demo
kafka:
bootstrap-servers: 192.168.200.130:9092
producer:
retries: 10
key-serializer: org.apache.kafka.common.serialization.StringSerializer
value-serializer: org.apache.kafka.common.serialization.StringSerializer
consumer:
group-id: ${spring.application.name}-test
key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
value-deserializer: org.apache.kafka.common.serialization.StringDeserializer
kafka:
hosts: 192.168.200.130:9092
group: ${spring.application.name}
3、新增配置类,创建KStream对象,进行聚合
package com.heima.kafkademo.stream;
import lombok.extern.slf4j.Slf4j;
import org.apache.kafka.streams.KeyValue;
import org.apache.kafka.streams.StreamsBuilder;
import org.apache.kafka.streams.kstream.KStream;
import org.apache.kafka.streams.kstream.TimeWindows;
import org.apache.kafka.streams.kstream.ValueMapper;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import java.time.Duration;
import java.util.Arrays;
@Configuration
@Slf4j
public class KafkaStreamHelloListener {
@Bean
public KStream<String,String> kStream(StreamsBuilder streamsBuilder){
//创建kstream对象,同时指定从那个topic中接收消息
KStream<String, String> stream = streamsBuilder.stream("itcast-topic-input");
stream.flatMapValues(new ValueMapper<String, Iterable<String>>() {
@Override
public Iterable<String> apply(String value) {
return Arrays.asList(value.split(" "));
}
})
//根据value进行聚合分组
.groupBy((key,value)->value)
//聚合计算时间间隔
.windowedBy(TimeWindows.of(Duration.ofSeconds(10)))
//求单词的个数
.count()
.toStream()
//处理后的结果转换为string字符串
.map((key,value)->{
System.out.println("key:"+key+",value:"+value);
return new KeyValue<>(key.key().toString(),value.toString());
})
//发送消息
.to("itcast-topic-out");
return stream;
}
}
4、启动kafka-demo服务测试
使用生产者发送消息可以看到控制台接收成功