Kafka简单客户端编程实例

Z时代
2024-01-10
分类：IT

今天，我们给大家带来一篇如何利用Kafka的API进行客户端编程的文章，这篇文章很简单，就是利用Kafka的API创建一个生产者和消费者，生产者不断向Kafka写入消息，消费者则不断消费Kafka的消息。下面是具体的实例代码。

一、创建配置类Config

这个类很简单，只是存放了两个常量，一个是话题TOPIC，一个是线程数THREADS


package com.lya.kafka; 
/** 
 * 配置项 
 * @author liuyazhuang 
 * 
 */ 
public class Config { 
 /** 
  * 话题 
  */ 
 public static final String TOPIC = "wordcount"; 
 /** 
  * 线程数 
  */ 
 public static final Integer THREADS = 1; 
}

二、编程生产者类ProducerDemo

这个类的主要作用就是向Kafka写入相应的消息，并且将消息写入wordcount话题。


package com.lya.kafka; 
import java.util.Properties; 
import kafka.javaapi.producer.Producer; 
import kafka.producer.KeyedMessage; 
import kafka.producer.ProducerConfig; 
/** 
 * 生产者实例 
 * @author liuyazhuang 
 * 
 */ 
public class ProducerDemo { 
 public static void main(String[] args) throws Exception { 
  Properties props = new Properties(); 
  props.put("zk.connect", "192.168.209.121:2181"); 
  props.put("metadata.broker.list","192.168.209.121:9092"); 
  props.put("serializer.class", "kafka.serializer.StringEncoder"); 
  props.put("zk.connectiontimeout.ms", "15000"); 
  ProducerConfig config = new ProducerConfig(props); 
  Producer<String, String> producer = new Producer<String, String>(config); 
  // 发送业务消息 
  // 读取文件 读取内存数据库 读socket端口 
  for (int i = 1; i <= 100; i++) { 
   Thread.sleep(500); 
   producer.send(new KeyedMessage<String, String>(Config.TOPIC, 
     "this number ===>>> " + i)); 
  } 
 } 
}

三、编写消息者类ConsumerDemo

这个类的主要作用就是消费Kafka中wordcount话题的消息。


package com.lya.kafka; 
import java.util.HashMap; 
import java.util.List; 
import java.util.Map; 
import java.util.Properties; 
import kafka.consumer.Consumer; 
import kafka.consumer.ConsumerConfig; 
import kafka.consumer.KafkaStream; 
import kafka.javaapi.consumer.ConsumerConnector; 
import kafka.message.MessageAndMetadata; 
/** 
 * 消费者实例 
 * @author liuyazhuang 
 * 
 */ 
public class ConsumerDemo { 
 public static void main(String[] args) { 
  Properties props = new Properties(); 
  props.put("zookeeper.connect", "192.168.209.121:2181"); 
  props.put("group.id", "1111"); 
  props.put("auto.offset.reset", "smallest"); 
  props.put("zk.connectiontimeout.ms", "15000"); 
  ConsumerConfig config = new ConsumerConfig(props); 
  ConsumerConnector consumer =Consumer.createJavaConsumerConnector(config); 
  Map<String, Integer> topicCountMap = new HashMap<String, Integer>(); 
  topicCountMap.put(Config.TOPIC, Config.THREADS); 
  Map<String, List<KafkaStream<byte[], byte[]>>> consumerMap = consumer.createMessageStreams(topicCountMap); 
  List<KafkaStream<byte[], byte[]>> streams = consumerMap.get(Config.TOPIC); 
  for(final KafkaStream<byte[], byte[]> kafkaStream : streams){ 
   new Thread(new Runnable() { 
    @Override 
    public void run() { 
     for(MessageAndMetadata<byte[], byte[]> mm : kafkaStream){ 
      String msg = new String(mm.message()); 
      System.out.println(msg); 
     } 
    } 
   }).start(); 
  } 
 } 
}