一、環境準備

請看上篇文章介紹kafka的部署與安裝，安裝成功之後，啟動kafka。

在Gradle中引入kafka-client依賴

 compile group: 'org.apache.kafka', name: 'kafka-clients', version: '1.1.0'

二、生產者建立

使用topic為test

import java.util.Properties;
import org.apache.kafka.clients.producer.Producer;
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.common.serialization.StringSerializer;

public class SimpleProducer
{

    public static void main(String[] args) throws Exception
    {
        String topicName = "test";

        // create instance for properties to access producer configs
        Properties props = new Properties();

        //Assign localhost id
        props.put("bootstrap.servers", "192.168.3.45:9092");

        //Set acknowledgements for producer requests.
        props.put("acks", "all");

        //If the request fails, the producer can automatically retry,
        props.put("retries", 0);

        //Specify buffer size in config
        props.put("batch.size", 16384);

        //Reduce the no of requests less than 0
        props.put("linger.ms", 1);

        //The buffer.memory controls the total amount of memory available to the producer for buffering.
        props.put("buffer.memory", 33554432);

        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class.getName());
        Producer<String, String> producer = new KafkaProducer<String, String>(props);

        for (int i = 0; i < 10; i++)
            producer.send(new ProducerRecord<String, String>(topicName, Integer.toString(i), Integer.toString(i)));
        System.out.println("Message sent successfully");
        producer.close();
    }
}
 

三、消費者建立

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

import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.common.serialization.StringDeserializer;

public class SimpleConsumer
{
    public static void main(String[] args) throws Exception
    {

        //Kafka consumer configuration settings
        String topicName = "test";
        Properties props = new Properties();

        props.put("bootstrap.servers", "192.168.3.45:9092");
        props.put("group.id", "test");
        props.put("enable.auto.commit", "true");
        props.put("auto.commit.interval.ms", "1000");
        props.put("session.timeout.ms", "30000");
        props.put("key.deserializer", StringDeserializer.class.getName());
        props.put("value.deserializer", StringDeserializer.class.getName());
        KafkaConsumer<String, String> consumer = new KafkaConsumer<String, String>(props);

        //Kafka Consumer subscribes list of topics here.
        consumer.subscribe(Arrays.asList(topicName));

        //print the topic name
        System.out.println("Subscribed to topic " + topicName);
        int i = 0;

        while (true)
        {
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord<String, String> record : records)

                // print the offset,key and value for the consumer records.
                System.out.printf("offset = %d, key = %s, value = %s\n", record.offset(), record.key(), record.value());
        }
    }
}
 

四、測試

首先啟動消費者程式SimpleConsumer，程式會阻塞，接著啟動生成者程式SimpleProducer，會發現消費者視窗接收到訊息

Subscribed to topic test
offset = 17, key = 0, value = 0
offset = 18, key = 1, value = 1
offset = 19, key = 2, value = 2
offset = 20, key = 3, value = 3
offset = 21, key = 4, value = 4
offset = 22, key = 5, value = 5
offset = 23, key = 6, value = 6
offset = 24, key = 7, value = 7
offset = 25, key = 8, value = 8
offset = 26, key = 9, value = 9