kafka producer consumer demo(三)

　　我们在前面把集群搭建起来了，也设置了kafka broker的配置，下面我们用代码来实现一下客户端向kafka发送消息，consumer端从kafka消费数据。大家先不要着急着了解

各种参数的配置，先感受一下整个流程，我会跟大家逐一深入的学习和探讨。

1.引入的maven依赖

<dependency>
    <groupId>org.apache.kafka</groupId>
    <artifactId>kafka-clients</artifactId>
    <version>0.11.0.1</version>
</dependency>

2.创建topic

bin/kafka-topics.sh --create --topic hello_kafka --partitions 3 --replication-factor 3 --zookeeper 192.168.1.11:2181/kafka 
#在zookeeper集群/kafka目录下创建 hello_kafka 主题，partitions 是3 副本3个

3.producer端代码

public class ProducerDemo {

    private static final Logger LOG = LoggerFactory.getLogger(ProducerDemo.class);

    public static void main(String[] args) throws InterruptedException, ExecutionException {
        //1.加载配置信息
        Properties prop = loadProperties();

        //2.创建生产者
        KafkaProducer<String,String> producer = new KafkaProducer<>(prop);

        String sendContent = "hello_kafka";
        ProducerRecord<String,String> record = new ProducerRecord<>("hello_kafka",sendContent);

        Future<RecordMetadata> future = producer.send(record);

        RecordMetadata recordMetadata = future.get();

        LOG.info("发送的数据是 {},offset 是{}",sendContent,recordMetadata.offset());

    }

    //配置文件的设置
    public static Properties loadProperties() {
        Properties prop = new Properties();
        prop.put("bootstrap.servers", "192.168.1.11:9092,192.168.1.12:9092,192.168.1.13:9092");
        prop.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        prop.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

        return prop;
    }
}

// 2019-08-05 23:17:22|INFO |com.zzh.hello.ProducerDemo 39|发送的数据是 hello_kafka,offset 是1

4.consumer端代码

public class ConsumerDemo {

    private static final Logger LOG = LoggerFactory.getLogger(ConsumerDemo.class);

    public static void main(String[] args) {
        //1.加载配置信息
        Properties prop = loadProperties();

        KafkaConsumer<String, String> consumer = new KafkaConsumer<>(prop);

        //1.订阅消息
        consumer.subscribe(Collections.singletonList("hello_kafka"));

        //2.读取消息
        for(;;) {

            ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
            records.forEach(items->
            {
                LOG.info("===============> offset:{},value:{}",items.offset(),items.value());
            }
            );
        }
    }

    private static Properties loadProperties() {
        Properties prop = new Properties();
        prop.put("bootstrap.servers", "192.168.1.11:9092,192.168.1.12:9092,192.168.1.13:9092");
        prop.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        prop.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        prop.put("group.id", "hello_2");
        prop.put("client.id", "demo-consumer-client");
        prop.put("auto.offset.reset", "earliest");        // earliest(最早) latest(最晚)

        return prop;
    }
}