Kafka消费者订阅分区 在命令行启动Kafka后，手动创建’assgin_topic’主题，分区数量为2，执行命令如下： .\bin\windows\kafka-topics.bat --create --zookeeper localhost:2181 --replication-factor 1 --partitions 2 --topic assign_topic 1. 根据上面给出的主题，完成如下操作： （1）编写生产者程序，以通用唯一标识符UUID作为消息，发送给主题assign_topic； （2）编写消费者程序1，订阅主题的分区0，只消费分区0数据； （3）编写消费者程序2，订阅主题的分区1，只消费分区1数据；

以下是相应的代码：

生产者程序：

import org.apache.kafka.clients.producer.*;
import java.util.Properties;
import java.util.UUID;

public class ProducerDemo {
    public static void main(String[] args) {
        String topicName = "assign_topic";
        Properties props = new Properties();
        props.put("bootstrap.servers", "localhost:9092");
        props.put("acks", "all");
        props.put("retries", 0);
        props.put("batch.size", 16384);
        props.put("linger.ms", 1);
        props.put("buffer.memory", 33554432);
        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        Producer<String, String> producer = new KafkaProducer<>(props);
        for (int i = 0; i < 10; i++) {
            String uuid = UUID.randomUUID().toString();
            producer.send(new ProducerRecord<>(topicName, uuid));
        }
        producer.close();
    }
}

消费者程序1：

import org.apache.kafka.clients.consumer.*;
import org.apache.kafka.common.TopicPartition;
import java.util.Collections;
import java.util.Properties;

public class ConsumerDemo1 {
    public static void main(String[] args) {
        String topicName = "assign_topic";
        Properties props = new Properties();
        props.put("bootstrap.servers", "localhost:9092");
        props.put("group.id", "test-group");
        props.put("enable.auto.commit", "true");
        props.put("auto.commit.interval.ms", "1000");
        props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
        TopicPartition partition0 = new TopicPartition(topicName, 0);
        consumer.assign(Collections.singletonList(partition0));
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord<String, String> record : records) {
                System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
            }
        }
    }
}

消费者程序2：

import org.apache.kafka.clients.consumer.*;
import org.apache.kafka.common.TopicPartition;
import java.util.Collections;
import java.util.Properties;

public class ConsumerDemo2 {
    public static void main(String[] args) {
        String topicName = "assign_topic";
        Properties props = new Properties();
        props.put("bootstrap.servers", "localhost:9092");
        props.put("group.id", "test-group");
        props.put("enable.auto.commit", "true");
        props.put("auto.commit.interval.ms", "1000");
        props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
        TopicPartition partition1 = new TopicPartition(topicName, 1);
        consumer.assign(Collections.singletonList(partition1));
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord<String, String> record : records) {
                System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
            }
        }
    }
}

生产者程序通过生成UUID作为消息，发送给主题"assign_topic"。消费者程序1订阅了主题"assign_topic"的分区0，只消费分区0数据；消费者程序2订阅了主题"assign_topic"的分区1，只消费分区1数据。