kafka是吞吐量巨大的一個(gè)消息系統(tǒng)，它是用scala寫的，和普通的消息的生產(chǎn)消費(fèi)還有所不同，寫了個(gè)demo程序供大家參考。kafka的安裝請參考官方文檔。

首先我們需要新建一個(gè)maven項(xiàng)目，然后在pom中引用kafka jar包，引用依賴如下：

<dependency>  
    <groupId>org.apache.kafka</groupId>  
    <artifactId>kafka_2.10</artifactId>  
    <version>0.8.0</version>  
</dependency>

舊版scala寫法， 下面我們看下生產(chǎn)消息的代碼：

package com.iaiai;  
  
import java.util.Properties;  
  
import kafka.javaapi.producer.Producer;  
import kafka.producer.KeyedMessage;  
import kafka.producer.ProducerConfig;  
  
/** 
 * Hello world! 
 * 
 */  
public class KafkaProducer   
{  
    private final Producer<String, String> producer;  
    public final static String TOPIC = "TEST-TOPIC";  
  
    private KafkaProducer(){  
        Properties props = new Properties();  
        //此處配置的是kafka的端口  
        props.put("metadata.broker.list", "192.168.193.148:9092");  
  
        //配置value的序列化類  
        props.put("serializer.class", "kafka.serializer.StringEncoder");  
        //配置key的序列化類  
        props.put("key.serializer.class", "kafka.serializer.StringEncoder");  
  
        //request.required.acks  
        //0, which means that the producer never waits for an acknowledgement from the broker (the same behavior as 0.7). This option provides the lowest latency but the weakest durability guarantees (some data will be lost when a server fails).  
        //1, which means that the producer gets an acknowledgement after the leader replica has received the data. This option provides better durability as the client waits until the server acknowledges the request as successful (only messages that were written to the now-dead leader but not yet replicated will be lost).  
        //-1, which means that the producer gets an acknowledgement after all in-sync replicas have received the data. This option provides the best durability, we guarantee that no messages will be lost as long as at least one in sync replica remains.  
        props.put("request.required.acks","-1");  
  
        producer = new Producer<String, String>(new ProducerConfig(props));  
    }  
  
    void produce() {  
        int messageNo = 1000;  
        final int COUNT = 10000;  
  
        while (messageNo < COUNT) {  
            String key = String.valueOf(messageNo);  
            String data = "hello kafka message " + key;  
            producer.send(new KeyedMessage<String, String>(TOPIC, key ,data));  
            System.out.println(data);  
            messageNo ++;  
        }  
    }  
  
    public static void main( String[] args )  
    {  
        new KafkaProducer().produce();  
    }  
}

最新的java版寫法:

package com.iaiai;

import kafka.producer.KeyedMessage;
import org.apache.kafka.clients.producer.Producer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;
import org.apache.kafka.common.serialization.StringSerializer;

import java.util.HashMap;
import java.util.Map;
import java.util.Properties;
import java.util.Random;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

/**
 * Created with IntelliJ IDEA.
 * Package: com.iaiai.db.service.impl
 * Author: iaiai
 * Create Time: 16/10/3 下午12:57
 * QQ: 176291935
 * Url: http://iaiai.iteye.com
 * Email: 176291935@qq.com
 * Description: 生產(chǎn)消息
 */
public class KafkaProducer {

    private final org.apache.kafka.clients.producer.KafkaProducer<String, String> producer;
    public final static String TOPIC = "TEST-TOPIC";

    private KafkaProducer(){
        Properties props = new Properties();
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.1.111:9092");
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,StringSerializer.class.getName());
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG,StringSerializer.class.getName());
//        props.put(ProducerConfig.ACKS_CONFIG)

        //request.required.acks
        //0, which means that the producer never waits for an acknowledgement from the broker (the same behavior as 0.7). This option provides the lowest latency but the weakest durability guarantees (some data will be lost when a server fails).
        //1, which means that the producer gets an acknowledgement after the leader replica has received the data. This option provides better durability as the client waits until the server acknowledges the request as successful (only messages that were written to the now-dead leader but not yet replicated will be lost).
        //-1, which means that the producer gets an acknowledgement after all in-sync replicas have received the data. This option provides the best durability, we guarantee that no messages will be lost as long as at least one in sync replica remains.
//        props.put("request.required.acks","-1");

        producer = new org.apache.kafka.clients.producer.KafkaProducer<String, String>(props);
    }

    void produce() {
        int messageNo = 1;
        final int COUNT = 2;

        while (messageNo < COUNT) {
            String key = String.valueOf(messageNo);
            String data = "hello kafka message " + key;
            boolean sync = false;   //是否同步

            if (sync) {
                try {
                    producer.send(new ProducerRecord<String, String>(TOPIC, data)).get();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            } else {
                producer.send(new ProducerRecord<String, String>(TOPIC, data));
            }

            //必須寫下面這句,相當(dāng)于發(fā)送
            producer.flush();

            messageNo ++;
        }
    }

    public static void main( String[] args ) {
        new KafkaProducer().produce();
    }

}

下面是消費(fèi)端的代碼實(shí)現(xiàn)：

package com.iaiai;  
  
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;  
  
    private KafkaConsumer() {  
        Properties props = new Properties();  
        //zookeeper 配置  
        props.put("zookeeper.connect", "192.168.193.148:2181");  
  
        //group 代表一個(gè)消費(fèi)組  
        props.put("group.id", "jd-group");  
  
        //zk連接超時(shí)  
        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");  
        //序列化類  
        props.put("serializer.class", "kafka.serializer.StringEncoder");  
  
        ConsumerConfig config = new ConsumerConfig(props);  
  
        consumer = kafka.consumer.Consumer.createJavaConsumerConnector(config);  
    }  
  
    void consume() {  
        Map<String, Integer> topicCountMap = new HashMap<String, Integer>();  
        topicCountMap.put(KafkaProducer.TOPIC, 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(KafkaProducer.TOPIC).get(0);  
        ConsumerIterator<String, String> it = stream.iterator();  
        while (it.hasNext())  
            System.out.println(it.next().message());  
    }  
  
    public static void main(String[] args) {  
        new KafkaConsumer().consume();  
    }  
}

注意消費(fèi)端需要配置成zk的地址，而生產(chǎn)端配置的是kafka的ip和端口。

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