kafka例子

    <dependencies>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>kafka_2.13</artifactId>
            <version>2.7.0</version>
        </dependency>
    </dependencies>

生产者

package com.test.producer;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.Properties;

public class MyProducer {

    public static void main(String[] args) {

        Properties properties = new Properties();

        properties.put("bootstrap.servers", "localhost:9092");
        // ack
        properties.put("acks", "all");
        // 重试次数
        properties.put("retries", 1);
        // 批次大小
        properties.put("batch.size", 16384);
        // 等待时间
        properties.put("linger.ms", 1);
        // 缓冲区大小
        properties.put("buffer.memory", 33554432);
        // 设置数据key和value的序列化处理类
        properties.put("key.serializer", StringSerializer.class);
        properties.put("value.serializer", StringSerializer.class);

        KafkaProducer<String, String> produce = new KafkaProducer<>(properties);

        for (int i=0; i < 2; i++) {
            produce.send(new ProducerRecord<>("test","key-"+i,"value--" + i));
        }

        produce.close();

    }
}

消费者

package com.test.consumer;

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.serialization.StringDeserializer;

import java.time.Duration;
import java.util.Arrays;
import java.util.Properties;

public class MyConsumer {

    public static void main(String[] args) {

        Properties properties = new Properties();

        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,"localhost:9092");
        // 自动提交
        properties.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG,true);
        // 提交延时
        properties.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG,"1000");
        // 反序列化
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        // 消费者组
        properties.put(ConsumerConfig.GROUP_ID_CONFIG,"bigdata");

        // 重置消费者的offset(换组、offset过期)
        properties.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG,"earliest");

        KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(properties);

        // 订阅主题
        consumer.subscribe(Arrays.asList("test"));

        // 获取数据
        while (true){
            ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));

            for(ConsumerRecord<String,String> record: records){
                System.out.println("key:" + record.key() + "" + ",value:" +record.value());

            }
        }

    }
}

带有callback的生产者

package com.test.producer;

import org.apache.kafka.clients.producer.*;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.Properties;

public class CallbackProducer {

    public static void main(String[] args) {

        Properties properties = new Properties();

        properties.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG,"localhost:9092");
        properties.put("key.serializer", StringSerializer.class);
        properties.put("value.serializer", StringSerializer.class);

        KafkaProducer<String, String> producer = new KafkaProducer<String, String>(properties);

        for (int i=0; i < 10; i++) {
            producer.send(new ProducerRecord<>("test","1","tt--" + i), (metadata, exception) -> {
                if (exception == null){
                    System.out.println(metadata.partition() + "--" + metadata.offset()) ;
                } else {
                    exception.printStackTrace();
                }
            });
        }

        producer.close();

    }

}