kafka初探 版本0.10 java编程

之前一直有项目用到，不过我并不负责这一块，所以了解不多，这次趁机会学习下。
之前对kafka的了解其实仅限于知道它是一个分布式消息系统，这次详细了解了下，知道了一些关键概念(topic主题、broker服务、producers消息发布者、consumer消息订阅者消费者)，具体网上一大堆，这里不赘述，直接开始代码。

1.引入包

    <dependency>        <groupId>org.apache.kafka</groupId>        <artifactId>kafka_2.10</artifactId>        <version>0.10.0.0</version>    </dependency>

实际上我倒不是以上面方式引入的，因为使用kafka还是为了后面跟spark steaming集成，所以我是引入的spark-streaming-kafka，依赖包自然会被引入，需求相同的话可以像下面这样引入。

    <dependency>        <groupId>org.apache.spark</groupId>        <artifactId>spark-streaming-kafka-0-10_2.11</artifactId>        <version>2.0.0</version>    </dependency>

2.发布者类Producer

这里使用KafkaProducer类,官方已经不建议使用Producer类，实现一个线程类，进行消息发布，实际的代码其实很简单，不过本来也就是要一个demo。

import java.util.Properties;import org.apache.kafka.clients.producer.KafkaProducer;import org.apache.kafka.clients.producer.ProducerRecord;public class UserKafkaProducer extends Thread{    private final KafkaProducer<Integer, String> producer;    private final String topic;    private final Properties props = new Properties();    public UserKafkaProducer(String topic)    {        props.put("metadata.broker.list", "master2:6667");        props.put("bootstrap.servers", "master2:6667");        props.put("acks", "all");        props.put("retries", 0);        props.put("batch.size", 16384);        props.put("linger.ms", 1);        props.put("buffer.memory", 33554432);        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");        producer = new KafkaProducer<Integer, String>(props);        this.topic = topic;    }    @Override    public void run() {        int messageNo = 1;        while (true)        {            String messageStr = new String("Message_" + messageNo);            System.out.println("Send:" + messageStr);            producer.send(new ProducerRecord<Integer, String>(topic, messageStr));            messageNo++;            try {                sleep(3000);            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }}

3.消息消费者类Consumer

import java.util.HashMap;import java.util.List;import java.util.Map;import java.util.Properties;import kafka.consumer.ConsumerConfig;import kafka.javaapi.consumer.ConsumerConnector;import kafka.consumer.ConsumerIterator;import kafka.consumer.KafkaStream;public class UserKafkaConsumer extends Thread{    private final ConsumerConnector consumer;    private final String topic;    public UserKafkaConsumer(String topic)    {        consumer = kafka.consumer.Consumer.createJavaConsumerConnector(                createConsumerConfig());        this.topic = topic;    }    private static ConsumerConfig createConsumerConfig()    {        Properties props = new Properties();        props.put("zookeeper.connect", "master1:2181,master2:2181");        props.put("group.id", "group1");        props.put("zookeeper.session.timeout.ms", "40000");        props.put("zookeeper.sync.time.ms", "200");        props.put("auto.commit.interval.ms", "1000");        return new ConsumerConfig(props);    }    @Override    public void run() {        Map<String, Integer> topicCountMap = new HashMap<String, Integer>();        topicCountMap.put(topic, new Integer(1));        Map<String, List<KafkaStream<byte[], byte[]>>> consumerMap = consumer.createMessageStreams(topicCountMap);        KafkaStream<byte[], byte[]> stream = consumerMap.get(topic).get(0);        ConsumerIterator<byte[], byte[]> it = stream.iterator();        while (it.hasNext()) {            System.out.println("receive：" + new String(it.next().message()));            try {                sleep(3000);            } catch (InterruptedException e) {                e.printStackTrace();            }        }    }}

4.简单示例

public static void main(String[] args)    {        UserKafkaProducer producerThread = new UserKafkaProducer(KafkaProperties.topic);        producerThread.start();        UserKafkaConsumer consumerThread = new UserKafkaConsumer(KafkaProperties.topic);        consumerThread.start();    }

运行即可。