Shades88 Shades88 - 1 year ago 174
Java Question

java client example for Kafka Producer, send method not accepting KeyedMessage

I am running kafka 2.9.1- I included jars provided in libs/ directory within main kafka directory. Now I am trying to run a java producer example as per what is given here Now

method seems to be accepting this kind of argument
Seq<KeyedMessage<String, String>>
. In the example, object of KeyedMessage is not converted into anything. When I try to do the same I get incompatible types compiler error.

Here's the code

import kafka.producer.KeyedMessage;
import kafka.producer.ProducerConfig;
import java.util.Properties;
import kafka.producer.Producer;
import scala.collection.Seq;

public class KakfaProducer {
public static void main(String [] args) {
Properties prop = new Properties();
prop.put("", "localhost:9092");
//prop.put("partitioner.class", "example.producer.SimplePartitioner");
ProducerConfig producerConfig = new ProducerConfig(prop);
Producer<String,String> producer = new <String,String>Producer(producerConfig);
String topic = "test";
KeyedMessage<String,String> message = new <String,String>KeyedMessage(topic, "Hello Test message");

And that commented code is giving me class def not found exception. I tried to look a lot on net, but it's not helping.

There are two kinds of jars in that libs/ directory. One is kafka-client and other one is just kafka and version number. Am I including wrong jar? Which one do I need to work with?

Answer Source

For the first problem, instead of importing scala API, import Java one. So, instead of using:

import kafka.producer.Producer;

please use:

import kafka.javaapi.producer.Producer;

SimplePartitioner code can be found below. Add it to the corresponding directory:

import kafka.producer.Partitioner;
import kafka.utils.VerifiableProperties;

public class SimplePartitioner implements Partitioner {
    public SimplePartitioner (VerifiableProperties props) {

    public int partition(Object key, int numPartitions) {
        int partition = 0;
        String stringKey = (String) key;
        int offset = stringKey.lastIndexOf('.');
        if (offset > 0) {
           partition = Integer.parseInt( stringKey.substring(offset+1)) % numPartitions;
       return partition;
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