Kafka study notes: Java operation Kafka

0x0 build environment

Go to the official website and see quick start
http://kafka.apache.org/quickstart
is too simple to write.

One thing to note:
To configure a property in server.properties:
advertised.host.name=host IP
otherwise you can only connect to kafka locally, and cannot be accessed externally.
You can see the instructions in the configuration file:

############################# Socket Server Settings #############################

# The address the socket server listens on. It will get the value returned from 
# java.net.InetAddress.getCanonicalHostName() if not configured.
#   FORMAT:
#     listeners = listener_name://host_name:port
#   EXAMPLE:
#     listeners = PLAINTEXT://your.host.name:9092
#listeners=PLAINTEXT://:9092

# Hostname and port the broker will advertise to producers and consumers. If not set, 
# it uses the value for "listeners" if configured.  Otherwise, it will use the value
# returned from java.net.InetAddress.getCanonicalHostName().
#advertised.listeners=PLAINTEXT://your.host.name:9092
advertised.host.name=192.168.80.224

0x1 Java code

Producer:

    @Test
    public void testProducer() throws ExecutionException, InterruptedException {
        Properties props = new Properties();

        props.put("bootstrap.servers", "192.168.80.224:9092");
        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

        //创建kafka的生产者类
        Producer<String, String> producer = new KafkaProducer<>(props);

        System.out.println("producer is created!");

        String topic = "test";
        producer.send(new ProducerRecord<String, String>(topic, "idea-key2", "java-message 1")).get();
        producer.send(new ProducerRecord<String, String>(topic, "idea-key2", "java-message 2")).get();
        producer.send(new ProducerRecord<String, String>(topic, "idea-key2", "java-message 3")).get();

        producer.close();
        System.out.println("producer is closed!");

    }

consumer:

@Test
    public void testConsumer() {
        String topic = "test";
        Properties props = new Properties();
        props.put("bootstrap.servers", "192.168.80.224:9092");//用于建立与 kafka 集群连接的 host/port 组。
        props.put("group.id", "testGroup1");// Consumer Group Name
        props.put("enable.auto.commit", "true");// Consumer 的 offset 是否自动提交
        props.put("auto.commit.interval.ms", "1000");// 自动提交 offset 到 zookeeper 的时间间隔，时间是毫秒
        props.put("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        props.put("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
        Consumer<String, String> consumer = new KafkaConsumer(props);
        consumer.subscribe(Arrays.asList(topic));
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord<String, String> record : records)
                System.out.printf("partition = %d, offset = %d, key = %s, value = %s%n", record.partition(), record.offset(), record.key(), record.value());
        }

The above code can be tested. Of course, you can open the producer and consumer that comes with kafka to view the message:

./bin/kafka-console-producer.sh --broker-list localhost:9092 --topic test

./bin/kafka-console-consumer.sh --bootstrap-server localhost:9092 --topic test