初识kafka 之 消费者API

需求

创建一个消费者，消费Mytopic主题指定分区3中的数据。

实现代码

package com.lzh.kafka;

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.Properties;
// kafka消费者 API
public class CustomConsumer {
    public static void main(String[] args) {
        // 0 配置
        Properties properties = new Properties();

        // 连接到服务器
        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,"bigdata01:9092,bigdata02:9092");

        // 反序列化
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,StringDeserializer.class.getName());

        // 添加groupid,必须
        properties.put(ConsumerConfig.GROUP_ID_CONFIG,"test");

        // 1 创建一个消费者对象
        KafkaConsumer<String, String> kafkaConsumer = new KafkaConsumer<String, String>(properties);

        // 2 订阅主题
        // ArrayList<String> topics = new ArrayList<String>();
        // topics.add("Mytopic");
        // kafkaConsumer.subscribe(topics); // 注册要消费的主题（可以消费多个主题）

        // 订阅指定分区 3
        ArrayList<TopicPartition> topicPartitions = new ArrayList<>();
        topicPartitions.add(new TopicPartition("Mytopic",3));
        kafkaConsumer.assign(topicPartitions); // 消费某个主题的某个分区数据


        // 3 消费数据
        // 一直获取消费数据
        while (true){
            ConsumerRecords<String, String> consumerRecords = kafkaConsumer.poll(Duration.ofSeconds(1));
            for (ConsumerRecord<String, String> consumerRecord : consumerRecords) {
                System.out.println(consumerRecord);
            }
        }
    }
}

结果