kafka笔记五 API

Kafka 的 Producer 发送消息采用的是异步发送的方式。在消息发送的过程中，涉及到了两个线程——main 线程和Sender 线程，以及一个线程共享变量——RecordAccumulator。

main 线程将消息发送给 RecordAccumulator，Sender 线程不断从 RecordAccumulator 中拉取消息发送到 Kafka broker。

dependencies

<!-- https://mvnrepository.com/artifact/org.apache.kafka/kafka -->
<dependency>
  <groupId>org.apache.kafka</groupId>
  <artifactId>kafka_2.12</artifactId>
  <version>2.1.1</version>
</dependency>

Producer

public class MyProducer {
    public static void main(String[] args) {
        //1 创建kafka生产者的配置信息
        Properties properties = new Properties();
        //2 kafka配置
        //指定kafka集群
        properties.put("bootstrap.servers","192.168.56.20:9092");
        //ack应答机制
        properties.put("acks","all");
        //重试次数
        properties.put("retries","3");
        //key，value的序列化类
        properties.put("key.serializer","org.apache.kafka.common.serialization.StringSerializer");
        properties.put("value.serializer","org.apache.kafka.common.serialization.StringSerializer");
        //3 创建生产者对象
        KafkaProducer<String, String> producer = new KafkaProducer<>(properties);
        //4 发送数据
        for (int i = 0; i < 100; i++) {
            producer.send(new ProducerRecord<>("first","atbdqn--"+i));
        }
        //5 关闭资源
        producer.close();
    }
}

Consumer

public class MyConsumer {
    public static void main(String[] args) {
        //1 创建消费者的配置信息
        Properties properties = new Properties();
        //2 给配置信息赋值
        properties.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.56.20:9092");
        // 开启自动提交
        properties.put(ConsumerConfig.AUTO_COMMIT_INTERVAL_MS_CONFIG,"1000");
        // 自动提交的延迟
        properties.put(ConsumerConfig.ENABLE_AUTO_COMMIT_CONFIG,true);
        // kv的反序列化类
        properties.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG,"org.apache.kafka.common.serialization.StringDeserializer");
        properties.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG,"org.apache.kafka.common.serialization.StringDeserializer");
        // 消费则组
        properties.put(ConsumerConfig.GROUP_ID_CONFIG,"gp1");
		// 3 创建消费者
        KafkaConsumer consumer = new KafkaConsumer<String,String>(properties);
		// 4 消费者消费的topic
        consumer.subscribe(Arrays.asList("first"));
        // 5 获取数据
        while (true) {
            ConsumerRecords<String,String> consumerRecords = consumer.poll(100);
            //解析并打印consumerRecords
            for (ConsumerRecord<String,String> consumerRecord : consumerRecords) {
                System.out.println(consumerRecord.key()+consumerRecord.value());
            }
        }
    }
}

自定义分区的Producer

		
public class MyPartitioner implements Partitioner {  //实现 Partitioner接口 重写方法
    @Override
    public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster) {
        //自定义分区方法
        Integer integer = cluster.partitionCountForTopic(topic);
        return key.toString().hashCode() % integer;
    }

    @Override
    public void close() {

    }

    @Override
    public void configure(Map<String, ?> configs) {

    }
}

public class PartitionProducer {
    public static void main(String[] args) {
        Properties prop = new Properties();
        prop.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG,"192.168.56.20:9092");
        prop.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG,"org.apache.kafka.common.serialization.StringSerializer");
        prop.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,"org.apache.kafka.common.serialization.StringSerializer");

        //添加分区器
        prop.put(ProducerConfig.PARTITIONER_CLASS_CONFIG,"com.atbdqn.partitioner.MyPartitioner");

        KafkaProducer<String, String> producer = new KafkaProducer<String, String>(prop);

        for (int i = 0; i < 10; i++) {
            producer.send(new ProducerRecord<String, String>("first", "atnjbdqn--" + i), (metadata, exception) -> {          //lanmbda表达式创建匿名对象
                if (exception == null){
                    System.out.println(metadata.partition()+"--"+metadata.offset());
                } else {
                    exception.printStackTrace();
                }
            });
        }
        producer.close();
    }
}