kafka消费者实例

1.配置文件 consumer.properties

#zookeeper地址
zookeeper.connect=master:2181,slave1:2181,slave2:2181
#zookeeper超时时间
zookeeper.connectiontimeout.ms=1000000
#kafka的consumer组
group.id=test-group



2. 组织代码
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import kafka.consumer.Consumer;
import kafka.consumer.ConsumerConfig;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;
import kafka.message.MessageAndMetadata;
public class init {
 public static void main(String[] args) throws FileNotFoundException, IOException {
  //1、读取配置文件
  Properties p = new Properties();
  //p.load(new FileInputStream(new File("./consumer.properties")));
  p.load(init.class.getClassLoader().getResourceAsStream("consumer.properties"));
  //2、通过配置文件，创建消费者配置
  ConsumerConfig config = new ConsumerConfig(p);
  //3、通过配置，创建消费者
  ConsumerConnector consumer = Consumer.createJavaConsumerConnector(config);
  //4、创建封装消息的map
  Map<String,Integer> topics = new HashMap<String,Integer>();
  //5、封装消费的topic名字和消费这个topic中几个partition
  topics.put("test-topic", 1);
  //6、创建消息流，传入刚刚创建的map
  Map<String, List<KafkaStream<byte[], byte[]>>> streams = consumer.createMessageStreams(topics);
  //7、获取消息，封装到list中
  List<KafkaStream<byte[], byte[]>> partitions = streams.get("test-topic");
  //8、创建线程池，用不同的线程消费list中的不同消息，可以消费一个，也可以消费多个
  ExecutorService threadPool = Executors.newFixedThreadPool(1);
  for(KafkaStream<byte[], byte[]> partition : partitions){
   //9、将消息传到线程中消费
   threadPool.execute(new TestConsumer(partition));
  }
 }
}


3.调用显示代码

import java.io.UnsupportedEncodingException;
import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.message.MessageAndMetadata;
public class TestConsumer extends Thread {
 private KafkaStream<byte[], byte[]> partition;
 /**
  * 构造函数，传进来消息
  */
 public TestConsumer(KafkaStream<byte[], byte[]> partition){
  this.partition = partition;
 }
 public void run() {
   //1、取出消息
   ConsumerIterator<byte[], byte[]> iterator = partition.iterator();
   //2、判断是否有下一条，有的话迭代消息，没有的话，停止等待
   while(iterator.hasNext()){
    //3、取出消息
    MessageAndMetadata<byte[], byte[]> next = iterator.next();
     try {
      //4、打印消息
              System.out.println("partiton:" + next.partition());//partition
              System.out.println("offset:" + next.offset());     //偏移量
              System.out.println("message:" + new String(next.message(), "utf-8"));//消息主体
     } catch (UnsupportedEncodingException e){
      e.printStackTrace();
     }
   }
 }