分布式消息队列kafka系列介绍 — 核心API介绍及实例

转自：http://www.inter12.org/archives/834

lskyne

9098人浏览 · 2014-09-02 17:52:16

lskyne · 2014-09-02 17:52:16 发布

转自：http://www.inter12.org/archives/834

一 PRODUCER的API

1.Producer的创建，依赖于ProducerConfig
public Producer(ProducerConfig config);

2.单个或是批量的消息发送
public void send(KeyedMessage<K,V> message);
public void send(List<KeyedMessage<K,V>> messages);

3.关闭Producer到所有broker的连接
public void close();

二 CONSUMER的高层API

主要是Consumer和ConsumerConnector，这里的Consumer是ConsumerConnector的静态工厂类
class Consumer {
public static kafka.javaapi.consumer.ConsumerConnector createJavaConsumerConnector(config: ConsumerConfig);
}

具体的消息的消费都是在ConsumerConnector中
创建一个消息处理的流，包含所有的topic，并根据指定的Decoder
public <K,V> Map<String, List<KafkaStream<K,V>>>
createMessageStreams(Map<String, Integer> topicCountMap, Decoder<K> keyDecoder, Decoder<V> valueDecoder);

创建一个消息处理的流，包含所有的topic，使用默认的Decoder
public Map<String, List<KafkaStream<byte[], byte[]>>> createMessageStreams(Map<String, Integer> topicCountMap);

获取指定消息的topic,并根据指定的Decoder
public <K,V> List<KafkaStream<K,V>>
createMessageStreamsByFilter(TopicFilter topicFilter, int numStreams, Decoder<K> keyDecoder, Decoder<V> valueDecoder);

获取指定消息的topic,使用默认的Decoder
public List<KafkaStream<byte[], byte[]>> createMessageStreamsByFilter(TopicFilter topicFilter);

提交偏移量到这个消费者连接的topic
public void commitOffsets();

关闭消费者
public void shutdown();

高层的API中比较常用的就是public List<KafkaStream<byte[], byte[]>> createMessageStreamsByFilter(TopicFilter topicFilter);和public void commitOffsets();

三 CONSUMER的简单API–SIMPLECONSUMER

批量获取消息
public FetchResponse fetch(request: kafka.javaapi.FetchRequest);

获取topic的元信息
public kafka.javaapi.TopicMetadataResponse send(request: kafka.javaapi.TopicMetadataRequest);

获取目前可用的偏移量
public kafka.javaapi.OffsetResponse getOffsetsBefore(request: OffsetRequest);

关闭连接
public void close();

对于大部分应用来说，高层API就已经足够使用了，但是若是想做更进一步的控制的话，可以使用简单的API，例如消费者重启的情况下，希望得到最新的offset，就该使用SimpleConsumer.

四 KAFKA HADOOP CONSUMER API

提供了一个可水平伸缩的解决方案来结合hadoop的使用参见

https://github.com/linkedin/camus/tree/camus-kafka-0.8/

五实战

maven依赖：

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

生产者代码：

  
        import  kafka.javaapi.producer.Producer;
       
        import  kafka.producer.KeyedMessage;
       
        import  kafka.producer.ProducerConfig;
       
        import  java.util.Properties;
       
        /**
       
         * <pre>
       
         * Created by zhaoming on 14-5-4 下午3:23
       
         * </pre>
       
         */
       
        public  class  KafkaProductor {
       
        public  static  void  main(String[] args) throws  InterruptedException {
       
        Properties properties = new  Properties();
       
         properties.put("zk.connect", "127.0.0.1:2181");
       
         properties.put("metadata.broker.list", "localhost:9092");
       
        properties.put("serializer.class", "kafka.serializer.StringEncoder");
       
        ProducerConfig producerConfig = new  ProducerConfig(properties);
       
         Producer<String, String> producer = new  Producer<String, String>(producerConfig);
       
        // 构建消息体
       
         KeyedMessage<String, String> keyedMessage = new  KeyedMessage<String, String>("test-topic", "test-message");
       
         producer.send(keyedMessage);
       
        Thread.sleep(1000);
       
        producer.close();
       
         }
       
        }

消费端代码

  
        import  java.io.UnsupportedEncodingException;
       
        import  java.util.List;
       
        import  java.util.Properties;
       
        import  java.util.concurrent.TimeUnit;
       
        import  kafka.consumer.*;
       
        import  kafka.javaapi.consumer.ConsumerConnector;
       
        import  kafka.message.MessageAndMetadata;
       
        import  org.apache.commons.collections.CollectionUtils;
       
        /**
       
         * <pre>
       
         * Created by zhaoming on 14-5-4 下午3:32
       
         * </pre>
       
         */
       
        public  class  kafkaConsumer {
       
        public  static  void  main(String[] args) throws  InterruptedException, UnsupportedEncodingException {
       
        Properties properties = new  Properties();
       
         properties.put("zookeeper.connect", "127.0.0.1:2181");
       
         properties.put("auto.commit.enable", "true");
       
         properties.put("auto.commit.interval.ms", "60000");
       
         properties.put("group.id", "test-group");
       
        ConsumerConfig consumerConfig = new  ConsumerConfig(properties);
       
        ConsumerConnector javaConsumerConnector = Consumer.createJavaConsumerConnector(consumerConfig);
       
         //topic的过滤器
       
         Whitelist whitelist = new  Whitelist("test-topic");
       
         List<KafkaStream<byte[], byte[]>> partitions = javaConsumerConnector.createMessageStreamsByFilter(whitelist);
       
        if  (CollectionUtils.isEmpty(partitions)) {
       
         System.out.println("empty!");
       
         TimeUnit.SECONDS.sleep(1);
       
         }
       
        //消费消息
       
         for  (KafkaStream<byte[], byte[]> partition : partitions) {
       
        ConsumerIterator<byte[], byte[]> iterator = partition.iterator();
       
         while  (iterator.hasNext()) {
       
         MessageAndMetadata<byte[], byte[]> next = iterator.next();
       
         System.out.println("partiton:"  + next.partition());
       
         System.out.println("offset:"  + next.offset());
       
         System.out.println("message:"  + new  String(next.message(), "utf-8"));
       
         }
       
        }
       
        }
       
        }