kafka8 编写简单消费者

1.eclipse运行消费者代码。代码如下

package cn.test.mykafka;

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

import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;


/**
 * 简单消费者
 *
 */

public class SimpleConsumer {

    public static void main(String[] args) {
        
        Properties props = new Properties();
        props.put("bootstrap.servers", "192.168.42.133:9092");
        props.put("group.id", "group1");
        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");
        
        @SuppressWarnings("resource")
        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
        consumer.subscribe(Arrays.asList("test-topic")); //订阅主题
        
        while (true) {
            @SuppressWarnings("deprecation")
            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());
        }
    }
}

2.在服务器生产消息

[root@hadoop kafka]# kafka-console-producer.sh --broker-list localhost:9092 --topic test-topic
>>test
>hello
>world

3.在eclipse控制台查看输出

offset = 118, key = null, value = test
offset = 119, key = null, value = hello
offset = 120, key = null, value = world

如上输出表示消费者成功消费消息。

offset偏移量：每消费一条消息，偏移量+1。

消费者消费的偏移量记载的是消费者组消费的该分区的消息的个数。

具体实现步骤参考 kafka5 编写简单生产者