kafka-生産者、消費者示例

生産者示例

Producer.java

import java.util.Properties;

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.common.KafkaException;
import org.apache.kafka.common.errors.AuthorizationException;
import org.apache.kafka.common.errors.OutOfOrderSequenceException;
import org.apache.kafka.common.errors.ProducerFencedException;
import org.apache.kafka.common.serialization.StringSerializer;

public class Producer {
	public static void main(String[] args) {
		testTransactionProducer();
	}

	/**
	 * 普通生産者
	 */
	public static void testProducer() {

		Properties props = new Properties();
		props.put("bootstrap.servers", "localhost:9092");
		props.put("acks", "all");
		props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
		props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

		KafkaProducer<String, String> producer = new KafkaProducer<String, String>(props);
		for (int i = 0; i < 10; i++)
			producer.send(new ProducerRecord<String, String>("my-topic", Integer.toString(i), Integer.toString(i)));

		producer.close();
	}

	/**
	 * 事務生産者
	 */
	public static void testTransactionProducer() {

		Properties props = new Properties();
		props.put("bootstrap.servers", "localhost:9092");
		props.put("transactional.id", "my-transactional-id");
		KafkaProducer<String, String> producer = new KafkaProducer<>(props, new StringSerializer(),
				new StringSerializer());

		producer.initTransactions();

		try {
			producer.beginTransaction();
			for (int i = 0; i < 3; i++)
				producer.send(new ProducerRecord<>("my-topic", Integer.toString(i), Integer.toString(i)));
			producer.commitTransaction();
		} catch (ProducerFencedException | OutOfOrderSequenceException | AuthorizationException e) {
			// We can't recover from these exceptions, so our only option is to close the
			// producer and exit.
			producer.close();
		} catch (KafkaException e) {
			// For all other exceptions, just abort the transaction and try again.
			producer.abortTransaction();
		}
		producer.close();

	}
}

           

消費者示例

Consumer.java

import java.time.Duration;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
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;

public class Consumer {
	public static void main(String[] args) {
		autoCommitConsumer();
	}

	/**
	 * 自動送出
	 */
	public static void autoCommitConsumer() {
		Properties props = new Properties();
		props.setProperty("bootstrap.servers", "localhost:9092");
		props.setProperty("group.id", "test");
		props.setProperty("enable.auto.commit", "true");
		props.setProperty("auto.commit.interval.ms", "1000");
		props.setProperty("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
		props.setProperty("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
		KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
		consumer.subscribe(Arrays.asList("foo", "bar", "my-topic"));
		while (true) {
			ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
			for (ConsumerRecord<String, String> record : records)
				System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
		}
	}

	/**
	 * 手動送出進度
	 */
	public static void manualCommitConsumer() {
		Properties props = new Properties();
		props.setProperty("bootstrap.servers", "localhost:9092");
		props.setProperty("group.id", "test");
		props.setProperty("enable.auto.commit", "false");
		props.setProperty("key.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
		props.setProperty("value.deserializer", "org.apache.kafka.common.serialization.StringDeserializer");
		KafkaConsumer<String, String> consumer = new KafkaConsumer<>(props);
		consumer.subscribe(Arrays.asList("foo", "bar", "my-topic"));
		final int minBatchSize = 10;
		List<ConsumerRecord<String, String>> buffer = new ArrayList<>();
		while (true) {
			ConsumerRecords<String, String> records = consumer.poll(Duration.ofMillis(100));
			for (ConsumerRecord<String, String> record : records) {
				buffer.add(record);
			}
			if (buffer.size() >= minBatchSize) {
				insertIntoDb(buffer);
				consumer.commitSync();
				buffer.clear();
			}
		}
	}

	private static void insertIntoDb(List<ConsumerRecord<String, String>> buffer) {
		System.out.println("把消息送出到資料庫。。。");

	}

}

           

參考

http://kafka.apache.org/24/javadoc/index.html?org/apache/kafka/clients/producer/KafkaProducer.html

http://kafka.apache.org/24/javadoc/index.html?org/apache/kafka/clients/consumer/KafkaConsumer.html