kafka复习：（23）事务

一、生产者，开启事务。

package com.cisdi.dsp.modules.metaAnalysis.rest.kafka2023;


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

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

public class KafkaTest22 {
    public static void main(String[] args) {
        Properties properties= new Properties();

        properties.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        properties.setProperty(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        properties.setProperty(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG,"xx.xx.xx.xx:9092");
        properties.setProperty(ProducerConfig.ENABLE_IDEMPOTENCE_CONFIG, "true");
        properties.setProperty(ProducerConfig.RETRIES_CONFIG, "2");
        properties.setProperty(ProducerConfig.MAX_IN_FLIGHT_REQUESTS_PER_CONNECTION, "4");
        properties.setProperty(ProducerConfig.TRANSACTIONAL_ID_CONFIG, "myTransaction");

        KafkaProducer kafkaProducer=new KafkaProducer(properties);
        ProducerRecord producerRecord=new ProducerRecord<>("study2024",0,"fff","hello sister,now is: "+ new Date());
        kafkaProducer.initTransactions();
        kafkaProducer.beginTransaction();
        try{
            Future future = kafkaProducer.send(producerRecord);
            long offset = 0;
            try {
                offset = future.get().offset();
            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }
            System.out.println(offset);

            Thread.sleep(60000);
            kafkaProducer.commitTransaction();
        } catch (Exception ex){
            kafkaProducer.abortTransaction();
        }


        kafkaProducer.close();
    }
}

二、消费者，设置隔离级别为"read_committed"

package com.cisdi.dsp.modules.metaAnalysis.rest.kafka2023;

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.clients.producer.ProducerConfig;
import org.apache.kafka.common.TopicPartition;
import org.apache.kafka.common.serialization.StringDeserializer;
import org.apache.kafka.common.serialization.StringSerializer;

import java.time.Duration;
import java.time.temporal.TemporalUnit;
import java.util.Arrays;
import java.util.Properties;
import java.util.concurrent.TimeUnit;

public class KafkaTest23 {

    private static Properties getProperties(){
        Properties properties=new Properties();

        properties.setProperty(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        properties.setProperty(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class.getName());
        properties.setProperty(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,"xx.xx.xx.xx:9092");
        properties.setProperty(ConsumerConfig.GROUP_ID_CONFIG,"testGroup");
        properties.setProperty(ConsumerConfig.ISOLATION_LEVEL_CONFIG, "read_committed");
        //properties.setProperty(ConsumerConfig.ISOLATION_LEVEL_CONFIG, "read_uncommitted");
        return properties;
    }
    public static void main(String[] args) {

        KafkaConsumer myConsumer=new KafkaConsumer(getProperties());
        String topic="study2024";
        myConsumer.subscribe(Arrays.asList(topic));

        while(true){
            ConsumerRecords consumerRecords=myConsumer.poll(Duration.ofMillis(5000));
            for(ConsumerRecord record: consumerRecords){
                System.out.println(record.value());
                System.out.println("record offset is: "+record.offset());
            }

        }



    }
}

三、运行结果，按照上述配置，当生产者发送消息并从kafka broker获取到offset后就会sleep,在生产者sleep的时候，消费者是获取不到消息的，只有sleep完成并提交事务之后，消费者才会获取到消息