Kafka客户端编程入门介绍

1.maven依赖

1<dependency>
2            <groupId>org.apache.kafka</groupId>
3            <artifactId>kafka_2.11</artifactId>
4            <version>1.0.0</version>
5        </dependency>

2.生产者

1import org.apache.kafka.clients.producer.Callback;
2import org.apache.kafka.clients.producer.KafkaProducer;
3import org.apache.kafka.clients.producer.ProducerRecord;
4import org.apache.kafka.clients.producer.RecordMetadata;
5
6import java.util.Properties;
7
8/**
9 * Created by zhangpeiran on 2018/9/30.
10 */
11public class MyProducer {
12    private static  class DemoProducerCallback implements Callback{
13        public void onCompletion(RecordMetadata recordMetadata,Exception e){
14            if(e != null)
15                e.printStackTrace();
16            else
17                System.out.print("send message success");
18        }
19    }
20
21    public static void main(String[] args){
22        Properties kafkaProps = new Properties();
23        kafkaProps.put("bootstrap.servers","ip1:9092,ip2:9092");
24        kafkaProps.put("key.serializer","org.apache.kafka.common.serialization.StringSerializer");
25        kafkaProps.put("value.serializer","org.apache.kafka.common.serialization.StringSerializer");
26
27        KafkaProducer producer = new KafkaProducer<String,String>(kafkaProps);
28
29        ProducerRecord<String,String> record = new ProducerRecord<String, String>("DemoTopic","DemoKey","DemoValue");
30
31        //async
32        producer.send(record,new DemoProducerCallback());
33        producer.close();
34    }
35}

3.自定义分区

1import org.apache.kafka.clients.producer.Partitioner;import org.apache.kafka.common.Cluster;import org.apache.kafka.common.record.InvalidRecordException;import org.apache.kafka.common.utils.Utils;import java.util.Map;/** * Created by zhangpeiran on 2018/10/8. */public class MyPartitioner implements Partitioner {    public void configure(Map<String,?> configs){}    public void close(){}    public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster) {        if((keyBytes == null) || !(key instanceof String))            throw new InvalidRecordException("Message should has a key");        int numPartitions = cluster.partitionsForTopic(topic).size();        return Math.abs(Utils.murmur2(keyBytes)) % numPartitions;    }}
2
3需要在Producer中加入配置：
4
5kafkaProps.put("partitioner.class","MyPartitioner");

 4.消费者

1import org.apache.kafka.clients.consumer.ConsumerRecord;
2import org.apache.kafka.clients.consumer.ConsumerRecords;
3import org.apache.kafka.clients.consumer.KafkaConsumer;
4
5import java.util.Collections;
6import java.util.Properties;
7
8/**
9 * Created by zhangpeiran on 2018/10/9.
10 */
11public class MyConsumer {
12
13    public static void main(String[] args){
14        Properties properties = new Properties();
15        properties.put("bootstrap.servers","ip1:9092,ip2:9092,ip3:9092");
16        properties.put("key.deserializer","org.apache.kafka.common.serialization.StringDeserializer");
17        properties.put("value.deserializer","org.apache.kafka.common.serialization.StringDeserializer");
18        properties.put("group.id","DemoConsumerGroup");
19
20        //默认值为latest，当消费者读取的分区没有偏移量或偏移量无效时，消费者将从最新的记录开始读
21        //当一个消费group第一次订阅主题时，符合这种情况，在Consumer启动之前，Producer生产的数据不会被读取
22        //置为earliest，表示从分区起始位置读取消息
23        properties.put("auto.offset.reset","earliest");
24
25        KafkaConsumer<String,String> consumer = new KafkaConsumer<String, String>(properties);
26
27        consumer.subscribe(Collections.singletonList("DemoTopic"));
28
29        try {
30            while (true){
31                ConsumerRecords<String,String> records = consumer.poll(100);
32                for(ConsumerRecord<String ,String> record : records){
33                    System.out.print(record.topic() + "," + record.partition() + "," + record.offset() + "," + record.key() + "," + record.value());
34                }
35            }
36        } finally {
37            consumer.close();
38        }
39    }
40}