技術標籤：kafka消費者kafka

手動維護offset

需要依賴

    <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-tx</artifactId>
            <version>5.0.8.RELEASE</version>
        </dependency>

通過事務的方式維護消費者消費的資料的offset和提交offset的統一性

package com.ln.kafka.custom;

import org.apache.kafka.clients.consumer.*;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.springframework.transaction.annotation.Transactional;
import org.springframework.transaction.interceptor.
 
TransactionAspectSupport;

import java.util.Arrays;
import java.util.Collection;
import java.util.Properties;

/**
 * @ProjectName: kafka
 * @Package: com.ln.kafka.custom
 * @Name:CustomOffsetCustomer
 * @Author:linianest
 * @CreateTime:2021/1/8 11:22
 * @version:1.0
 * @Description TODO: 手動維護offset
 */
public
 
 class CustomOffsetCustomer {
    public static void main(String[] args) {
        Properties props = new Properties();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, "hadoop101:9092");
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "1234");
        // 自動提交offset,關閉預設,自動提交效率可能慢
        props.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG, "false");
        // 預設自動提交offset的時間是5秒
//        props.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG, 1000);

        // 建立物件
        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
        // 自定義維護offset
        consumer.subscribe(Arrays.asList("first"), new ConsumerRebalanceListener() {
            // todo 重新分配分割槽前，提交當前負責的分割槽的offset
            @Override
            public void onPartitionsRevoked(Collection<TopicPartition> collection) {
                System.out.println("=======回收的分割槽============");
                for (TopicPartition partition : collection) {
                    System.out.println("partition=" + partition);
                }
            }

            // todo 重新分配分割槽後，定位新分配的分割槽的offset
            @Override
            public void onPartitionsAssigned(Collection<TopicPartition> partitions) {
                System.out.println("=======重新得到的分割槽============");
                for (TopicPartition partition : partitions) {
                    System.out.println("partition=" + partition);
                    // todo 從offset的儲存地方獲取值,redis或者mysql
                    Long offset = getPartitionOffset(partition);
                    consumer.seek(partition, offset);
                }
            }


        });
        while (true) {
            // 拉取資料
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord record : records) {
                // todo 為了避免漏消費或者重複消費的問題，開啟個事務
                //===================================
                // 消費資料
                ConsumMessage(record);
                //===================================
            }

        }
    }

    // 消費資料
    @Transactional(rollbackFor = Exception.class)
    private static void ConsumMessage(ConsumerRecord record) {
        System.out.printf("topic=%d,key=%s,value=%s%n", record.topic(), record.offset(), record.value());
        try{
            // 自己維護offset
            TopicPartition topicPartition = new TopicPartition(record.topic(), record.partition());
            // todo 提交offset
            commitOffset(topicPartition, record.offset() + 1);
        }catch (Exception e){
            //設定手動回滾
            TransactionAspectSupport.currentTransactionStatus()
                    .setRollbackOnly();
        }
    }

    /**
     * todo 提交offset,可以將offset維護到其他裝置，如mysql或者redis中
     *
     * @param topicPartition
     * @param l
     */
    private static void commitOffset(TopicPartition topicPartition, long l) {
    }

    /**
     * todo 獲取分割槽offset
     *
     * @param partition
     * @return
     */
    private static Long getPartitionOffset(TopicPartition partition) {
        return null;
    }
    // 關閉資料流
}