kafka producer partitions分区器(七)

　　消息在经过拦截器、序列化后，就需要确定它发往哪个分区，如果在ProducerRecord中指定了partition字段，那么就不再需要partitioner分区器进行分区了，如果没有指定，那么会根据key来将数据进行分区，如果partitioner和key都没有指定，那么就会采用默认的方式进行数据分区。

　　有没有指定partition可以从源码中看出：

 public ProducerRecord(String topic, Integer partition, K key, V value) {}
 
 如果指定的partition,那就指定了数据发往哪个分区上，如果没有就会根据key来进行数据分区，如果2个都没有，那么会采用默认的分区策略来进行数据分区

1.根据key进行分区

public class CustomPartitioner {
    
    private static final Logger LOG = LoggerFactory.getLogger(CustomPartitioner.class);
    
    public static void main(String[] args) {
        //1.加载配置信息
        Properties prop = loadProperties();
        
        //2.创建生产者
        KafkaProducer<Integer,String> producer = new KafkaProducer<>(prop);
        
        String sendContent = "hello_kafka";
        IntStream.range(0, 10).forEach(i ->{
            try {
                ProducerRecord<Integer,String> record = new ProducerRecord<>("test1",i,sendContent+"_"+i);　　//topic key value
                Future<RecordMetadata> future = producer.send(record);
                RecordMetadata recordMetadata = future.get();
                LOG.info("发送的数据是 :{},offset:是{},partition是：{}",sendContent,recordMetadata.offset(),recordMetadata.partition());
            } catch (Exception e) {
                e.printStackTrace();
            }
            
        });
        
    }
     //配置文件的设置
    public static Properties loadProperties() {
        Properties prop = new Properties();
        prop.put("bootstrap.servers", "192.168.100.144:9092,192.168.100.145:9092,192.168.100.146:9092");
        prop.put("key.serializer", "org.apache.kafka.common.serialization.IntegerSerializer");
        prop.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        prop.put("acks", "all");    //发送到所有的ISR队列中
        return prop;
    }
}

 2.自定义分区

　　同样在使用自定义分区的时候，需要写实现类和在producer中配置引用

　　我们在这个示例中，根据key来分区，key在序列化的时候用的是IntegerSerializer,在ProducerRecord中我们没有指定partition

　　自定义分区器

public class CustomPartition implements Partitioner{

    @Override
    public void configure(Map<String, ?> configs) {
        // TODO Auto-generated method stub
        
    }

    @SuppressWarnings({ "null", "unused" })
    @Override
    public int partition(String topic, Object key, byte[] keyBytes, Object value, byte[] valueBytes, Cluster cluster) {
        
        int partitionNum = cluster.partitionsForTopic(topic).size();
        int partition = (Integer)key%partitionNum;
        return key == null? 0:partition;
    }

    @Override
    public void close() {
        // TODO Auto-generated method stub
        
    }
}

　　生产者

public class ProducerDemo {
    
    private static final Logger LOG = LoggerFactory.getLogger(ProducerDemo.class);
        
    public static void main(String[] args) throws InterruptedException, ExecutionException {
        //1.加载配置信息
        Properties prop = loadProperties();
        
        //2.创建生产者
        KafkaProducer<Integer,String> producer = new KafkaProducer<>(prop);
        
        //3.发送内容
        String sendContent = "hello_kafka";
        IntStream.range(0, 10).forEach(i ->{
            try {
                ProducerRecord<Integer,String> record = new ProducerRecord<>("test1",i,sendContent+"_"+i);
                Future<RecordMetadata> future = producer.send(record);
                RecordMetadata recordMetadata = future.get();
                LOG.info("发送的数据是 :{},offset:是{},partition是：{}",sendContent,recordMetadata.offset(),recordMetadata.partition());
            } catch (Exception e) {
                e.printStackTrace();
            }
            
        });                
        producer.close();    //回调拦截器中的close方法
        
    }
        
    //配置文件的设置
    public static Properties loadProperties() {
        Properties prop = new Properties();
        prop.put("bootstrap.servers", "192.168.100.144:9092,192.168.100.145:9092,192.168.100.146:9092");
        prop.put("key.serializer", "org.apache.kafka.common.serialization.IntegerSerializer");
        prop.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        prop.put("partitioner.class", "com.zpb.partitioner.CustomPartition");
        prop.put("acks", "all");
        return prop;
    }
}