Apache Kafka 简明教程

producer.send(new ProducerRecord<byte[],byte[]>(topic,
partition, key1, value1) , callback);

public void flush()

public Map metrics()

//import util.properties packages
import java.util.Properties;

//import simple producer packages
import org.apache.kafka.clients.producer.Producer;

//import KafkaProducer packages
import org.apache.kafka.clients.producer.KafkaProducer;

//import ProducerRecord packages
import org.apache.kafka.clients.producer.ProducerRecord;

//Create java class named “SimpleProducer”
public class SimpleProducer {

   public static void main(String[] args) throws Exception{

      // Check arguments length value
      if(args.length == 0){
         System.out.println("Enter topic name");
         return;
      }

      //Assign topicName to string variable
      String topicName = args[0].toString();

      // create instance for properties to access producer configs
      Properties props = new Properties();

      //Assign localhost id
      props.put("bootstrap.servers", “localhost:9092");

      //Set acknowledgements for producer requests.
      props.put("acks", “all");

      //If the request fails, the producer can automatically retry,
      props.put("retries", 0);

      //Specify buffer size in config
      props.put("batch.size", 16384);

      //Reduce the no of requests less than 0
      props.put("linger.ms", 1);

      //The buffer.memory controls the total amount of memory available to the producer for buffering.
      props.put("buffer.memory", 33554432);

      props.put("key.serializer",
         "org.apache.kafka.common.serialization.StringSerializer");

      props.put("value.serializer",
         "org.apache.kafka.common.serialization.StringSerializer");

      Producer<String, String> producer = new KafkaProducer
         <String, String>(props);

      for(int i = 0; i < 10; i++)
         producer.send(new ProducerRecord<String, String>(topicName,
            Integer.toString(i), Integer.toString(i)));
               System.out.println(“Message sent successfully”);
               producer.close();
   }
}

javac -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*” *.java

java -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*”:. SimpleProducer <topic-name>

Message sent successfully
To check the above output open new terminal and type Consumer CLI command to receive messages.
>> bin/kafka-console-consumer.sh --zookeeper localhost:2181 —topic <topic-name> —from-beginning
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public KafkaConsumer(java.util.Map<java.lang.String,java.lang.Object> configs)

public ConsumerRecord(string topic,int partition, long offset,K key, V value)

public ConsumerRecords(java.util.Map<TopicPartition,java.util.List
<Consumer-Record>K,V>>> records)

import java.util.Properties;
import java.util.Arrays;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.ConsumerRecord;

public class SimpleConsumer {
   public static void main(String[] args) throws Exception {
      if(args.length == 0){
         System.out.println("Enter topic name");
         return;
      }
      //Kafka consumer configuration settings
      String topicName = args[0].toString();
      Properties props = new Properties();

      props.put("bootstrap.servers", "localhost:9092");
      props.put("group.id", "test");
      props.put("enable.auto.commit", "true");
      props.put("auto.commit.interval.ms", "1000");
      props.put("session.timeout.ms", "30000");
      props.put("key.deserializer",
         "org.apache.kafka.common.serialization.StringDeserializer");
      props.put("value.deserializer",
         "org.apache.kafka.common.serialization.StringDeserializer");
      KafkaConsumer<String, String> consumer = new KafkaConsumer
         <String, String>(props);

      //Kafka Consumer subscribes list of topics here.
      consumer.subscribe(Arrays.asList(topicName))

      //print the topic name
      System.out.println("Subscribed to topic " + topicName);
      int i = 0;

      while (true) {
         ConsumerRecords<String, String> records = con-sumer.poll(100);
         for (ConsumerRecord<String, String> record : records)

         // print the offset,key and value for the consumer records.
         System.out.printf("offset = %d, key = %s, value = %s\n",
            record.offset(), record.key(), record.value());
      }
   }
}

javac -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*” *.java

java -cp “/path/to/kafka/kafka_2.11-0.9.0.0/lib/*”:. SimpleConsumer <topic-name>

Subscribed to topic Hello-Kafka
offset = 3, key = null, value = Hello Consumer