kafka消息中间件及java示例

Posted 2020-08-10

kafka是一个消息中间件，用于各个系统之间传递消息，并且消息可持久化！

可以认为是队列模型，也可以看作是生产者消费着模型；

简单的生产者消费者客户端代码如下：

package com.pt.util.kafka;

import java.util.Date;
import java.util.Properties;

import kafka.javaapi.producer.Producer;
import kafka.producer.KeyedMessage;
import kafka.producer.ProducerConfig;

public class MyProducer {
    public static void sendMsg(String msg) {
        Properties props = new Properties();
        //brokers list
        props.put("metadata.broker.list", "192.168.91.231:9092,192.168.91.231:9093");
        /* *
         * the serializer when preparing the message for transmission to the Broker
         * Note that the encoder must accept the same type 
         * as defined in the KeyedMessage object in the next step. 
         * 
         */
        props.put("serializer.class", "kafka.serializer.StringEncoder");
        /* *
         * defines what class to use to determine 
         * which Partition in the Topic the message is to be sent to
         */
        props.put("partitioner.class", "example.producer.SimplePartitioner");
        /* *
         *  tells Kafka that you want your Producer to require an 
         *  acknowledgement from the Broker that the message was received
         */
        props.put("request.required.acks", "1");

        ProducerConfig config = new ProducerConfig(props);
        /*
         * Note that the Producer is a Java Generic and you need to tell it the type of two parameters.
         * The first is the type of the Partition key, the second the type of the message.
         */
        Producer<String, String> producer = new Producer<String, String>(config);

        long runtime = new Date().getTime();
        String ip = "192.168.91.231";
        /*
         * The “panteng” is the Topic to write to. 
         * Here we are passing the IP as the partition key.
         * Note that if you do not include a key, 
         * even if you‘ve defined a partitioner class, Kafka will assign the message to a random partition.
         */
        KeyedMessage<String, String> data = new KeyedMessage<String, String>(
                "panteng", ip, msg);
        producer.send(data);
        producer.close();
    }
}

Producer,java

package cn.outofmemory.kafka;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;

import kafka.consumer.ConsumerConfig;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;
import kafka.serializer.StringDecoder;
import kafka.utils.VerifiableProperties;

public class KafkaConsumer {

    private final ConsumerConnector consumer;

    public KafkaConsumer() {
        Properties props = new Properties();
        //zookeeper 配置
        props.put("zookeeper.connect", "192.168.91.231:2181");
        //group 代表一个消费组
        props.put("group.id", "jd-group");

        //zk连接超时
        props.put("zookeeper.session.timeout.ms", "4000");
        props.put("zookeeper.sync.time.ms", "200");
        props.put("auto.commit.interval.ms", "1000");
        props.put("auto.offset.reset", "smallest");
        //序列化类
        props.put("serializer.class", "kafka.serializer.StringEncoder");
        ConsumerConfig config = new ConsumerConfig(props);
        consumer = kafka.consumer.Consumer.createJavaConsumerConnector(config);
    }

    public void consume() {
        Map<String, Integer> topicCountMap = new HashMap<String, Integer>();
        topicCountMap.put("panteng", new Integer(1));

        StringDecoder keyDecoder = new StringDecoder(new VerifiableProperties());
        StringDecoder valueDecoder = new StringDecoder(new VerifiableProperties());

        Map<String, List<KafkaStream<String, String>>> consumerMap = 
                consumer.createMessageStreams(topicCountMap,keyDecoder,valueDecoder);
        KafkaStream<String, String> stream = consumerMap.get("panteng").get(0);
        ConsumerIterator<String, String> it = stream.iterator();
        while (it.hasNext())
            System.out.println(it.next().message());
    }
    
    public void stop(){
        try {
            consumer.shutdown();
        } catch (Exception e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        
    }
    public static void main(String[] args) {
        new KafkaConsumer().consume();
    }
}

Consumer.java