[kafka] 005_kafka_Java_API

1、生产者Producer

1）添加依赖

    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
        <version>0.10.0.0</version>
    </dependency>

2）简单推送代码

文档参考：http://kafka.apache.org/0100/javadoc/index.html?org/apache/kafka/clients/producer/KafkaProducer.html

同步推送：

 Properties props = new Properties();

 props.put("bootstrap.servers", "localhost:9092");
 props.put("acks", "all");
 props.put("retries", 0);
 props.put("batch.size", 16384);
 props.put("linger.ms", 1);
 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<>(props);

 for(int i = 0; i < 100; i++)
     producer.send(new ProducerRecord<String, String>("my-topic", Integer.toString(i), Integer.toString(i)));

 producer.close();

异步推送：

public Future<RecordMetadata> send(ProducerRecord<K,V> record,Callback callback)

对比：

If you want to simulate a simple blocking call you can call the get() method immediately:

 byte[] key = "key".getBytes();
 byte[] value = "value".getBytes();
 ProducerRecord<byte[],byte[]> record = new ProducerRecord<byte[],byte[]>("topic1", key, value)
 producer.send(record).get();
 
Fully non-blocking usage can make use of the Callback parameter to provide a callback that will be invoked when the request is complete.

 ProducerRecord<byte[],byte[]> record = new ProducerRecord<byte[],byte[]>("topic1", key, value);
 producer.send(myRecord,
               new Callback() {
                   public void onCompletion(RecordMetadata metadata, Exception e) {
                       if(e != null)
                           e.printStackTrace();
                       System.out.println("The offset of the record we just sent is: " + metadata.offset());
                   }
               });

2、消费者Consumer

1）添加依赖

    <dependency>
        <groupId>org.apache.kafka</groupId>
        <artifactId>kafka-clients</artifactId>
        <version>0.10.0.0</version>
    </dependency>

2）简单拉取代码

更多请查看：http://kafka.apache.org/0100/javadoc/index.html?org/apache/kafka/clients/consumer/KafkaConsumer.html

　　 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<>(props);
     consumer.subscribe(Arrays.asList("foo", "bar"));

     while (true) {
         ConsumerRecords<String, String> records = consumer.poll(100);
         for (ConsumerRecord<String, String> record : records)
             System.out.printf("offset = %d, key = %s, value = %s", 
　　　　　　　　　　record.offset(), record.key(), record.value());
     }

附上以验证通过的producer推送代码：

    public RecordMetadata sendSyncKafkaRequest(String topic, KeyModel keyModel, Object message) {

        logger.info("=== 推送服务开始：sendSyncKafkaRequest start ===");
        logger.info("=== topic: " + topic + "===");
        logger.info("=== keyModel: " + JSON.toJSONString(keyModel) + "===");
        logger.info("=== message: " + JSON.toJSONString(message) + "===");

        Properties props = kafkaProducerProperties.getProperties();
        KafkaProducer<KeyModel, Object> producer = null;
        RecordMetadata recordMetadata = null;
        try {
            producer = new KafkaProducer<KeyModel, Object>(props);

            recordMetadata = producer.send(new ProducerRecord<KeyModel, Object>(topic, keyModel,  message)).get();

        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }

        if (recordMetadata != null) {
            logger.info("===kafka请求推送成功！Topic：" + recordMetadata.topic() + ";分区：" + recordMetadata.partition() + "===");
        } else {
            logger.info("=== recordMetadata为 null!本次kafka 写入请求没有完成!===");
        }

        return recordMetadata;
    }