Generator and consumer code of java's kafka client

background

In order to improve development efficiency, it is often used to test and understand kafka configuration.

rely

 <dependency>
     <groupId>org.apache.kafka</groupId>
     <artifactId>kafka-clients</artifactId>
     <version>3.2.0</version>
 </dependency>

producer

package com.example.demo.mqtt;

import com.alibaba.fastjson.JSON;
import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.Properties;
import java.util.concurrent.ExecutionException;

/**
 * @date 2022/11/2 14:39
 */
public class KafkaProducerDemo {
    
    
    public static void main(String[] args) {
    
    
        //1.创建kafka生产者配置对象
        Properties props = new Properties();
        //2.给 kafka 配置对象添加配置信息：bootstrap.servers
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.1.111:9092");
        //key,value 序列化（必须）
        //把发送的key从字符串序列化为字节数组
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        //把发送消息value从字符串序列化为字节数组
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        // 3. 创建 kafka 生产者对象
        Producer<String, String> producer = new KafkaProducer<>(props);

        Order order = new Order((long) 1, 100);
        ProducerRecord<String, String> producerRecord = new ProducerRecord<>("my-topic", JSON.toJSONString(order));
        //4. 调用 send 方法,发送消息
        RecordMetadata metadata = null;
        try {
    
    
            metadata = producer.send(producerRecord).get();
        } catch (InterruptedException e) {
    
    
            throw new RuntimeException(e);
        } catch (ExecutionException e) {
    
    
            throw new RuntimeException(e);
        }
        producer.close();
        //=====阻塞=======
        System.out.println("同步方式发送消息结果：" + "topic-" + metadata.topic() + "|partition-" + metadata.partition() + "|offset-" + metadata.offset());

    }
}

consumer

package com.example.demo.mqtt;


import org.apache.kafka.clients.consumer.ConsumerConfig;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.serialization.StringDeserializer;

import java.time.Duration;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

/**
 * @date 2022/10/11 19:26
 */
public class KafkaConsumerDemo {
    
    
    public static void main(String[] args) {
    
    

        Properties properties = new Properties();
        //borker地址
        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.1.111:9092");
        //反序列化方式
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,StringDeserializer.class.getName());
        //指定消费者组id，必须
        properties.put(ConsumerConfig.GROUP_ID_CONFIG,"group11111");
        //earliest:offset偏移至最早时候开始消费；latest：偏移到从最新开始消费（默认）
        properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG,"earliest");
        //每批次最小拉取数据大小,默认1byte
        properties.put(ConsumerConfig.FETCH_MIN_BYTES_CONFIG,1);
        //每批次最大拉取数据大小，默认50M
        properties.put(ConsumerConfig.FETCH_MAX_BYTES_CONFIG,50 * 1024 * 1024);
        //一批次数据，未达到最小数据大小时候，最大等待时间.默认500ms
        properties.put(ConsumerConfig.FETCH_MAX_WAIT_MS_CONFIG,500);
        //单次调用 poll() 返回的最大记录数,默认500
        properties.put(ConsumerConfig.MAX_POLL_RECORDS_CONFIG,500);
        KafkaConsumer kafkaConsumer = new KafkaConsumer(properties);
        //A.设置要订阅的topic 列表
        List<TopicPartition> topicPartitions = new ArrayList<>();
        topicPartitions.add(new TopicPartition("my-topic",0));
        kafkaConsumer.assign(topicPartitions);
        while (true){
    
    
            ConsumerRecords<String,String> records = kafkaConsumer.poll(Duration.ofSeconds(2L));
            for (ConsumerRecord<String,String> record : records) {
    
    
                System.out.println("消费数据。topic: "+record.topic()+"|partition:"+record.partition()+"|数据："+record.value());
            }
        }
    }

}