kafka 自定义Interceptor（通过拦截器对消息进行定制化处理）

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1. 说明

  producer生成消息时，interceptor使得用户在消息发送前以及producer回调逻辑触发前对消息做定制化处理。producer允许用户通过配置interceptor.classes参数指定多个interceptor按序作用于同一条消息从而形成一个拦截链(interceptor chain)。Intercetpor的实现接口是org.apache.kafka.clients.producer.ProducerInterceptor

1.1 configure(configs)

  可获取配置信息，初始化调用一次

1.2 onSend(ProducerRecord)

  方法会运行在用户主线程中，封装进org.apache.kafka.clients.producer.KafkaProducer#send(ProducerRecord, Callback)，确保在消息被序列化以及计算分区前调用。（最好不要修改消息所属的topic和分区）

1.3 onAcknowledgement(RecordMetadata, Exception)

  方法会在消息从RecordAccumulator成功发送到Kafka Broker之后，或者在发送过程中失败时调用，即在producer回调逻辑触发之前调用。（不要添加复杂逻辑，否则会拖慢producer的消息发送效率）

1.4 close

  关闭拦截器，执行资源清理工作

注：producer将按照指定顺序调用拦截器，并仅捕获每个interceptor可能抛出的异常记录到错误日志中而非在向上传递。

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2. 案例

  生成拦截链。第一个interceptor会在消息发送前将时间戳信息加到消息value的最前部；第二个interceptor会在消息发送后更新成功发送消息数或失败发送消息数到控制台

拦截器一：

import org.apache.kafka.clients.producer.ProducerInterceptor;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;

import java.util.Map;

public class TimeInterceptor implements ProducerInterceptor<String, String> {

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

    }

    @Override
    public ProducerRecord<String, String> onSend(ProducerRecord<String, String> record) {
        return new ProducerRecord<String, String>(record.topic(), record.partition(), record.key(), System.currentTimeMillis() + "----" + record.value());
    }

    @Override
    public void onAcknowledgement(RecordMetadata metadata, Exception exception) {

    }

    @Override
    public void close() {

    }

}

拦截器二：

import org.apache.kafka.clients.producer.ProducerInterceptor;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;

import java.util.Map;

public class CounterInterceptor implements ProducerInterceptor<String, String> {
    private int success;
    private int error;

    @Override
    public ProducerRecord<String, String> onSend(ProducerRecord<String, String> record) {
        return record;
    }

    @Override
    public void onAcknowledgement(RecordMetadata metadata, Exception exception) {
        if (metadata != null) {
            success++;
        } else {
            error++;
        }
    }

    @Override
    public void close() {
        System.out.println("success:" + success);
        System.out.println("error:" + error);
    }

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

    }
}

生产者：

import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;

import java.util.ArrayList;
import java.util.Properties;

public class InterceptorProducer {
    public static void main(String[] args) throws InterruptedException {

        Properties props = new Properties();

        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, "192.168.0.23:29092,192.168.0.114:29092,192.168.0.110:29092");
        //ack应答级别
        props.put(ProducerConfig.ACKS_CONFIG, "all");
        //重试次数
        props.put("retries", 1);
        //批次大小
        props.put("batch.size", 16384);
        //等待时间
        props.put("linger.ms", 1);
        //RecordAccumulator缓冲区大小
        props.put("buffer.memory", 33554432);
        // key value 序列化
        props.put("key.serializer", "org.apache.kafka.common.serialization.StringSerializer");
        props.put("value.serializer", "org.apache.kafka.common.serialization.StringSerializer");

        /*添加拦截器链*/
        ArrayList<String> classes = new ArrayList<>();
        classes.add("com.cz.kafka.interceptor.TimeInterceptor");
        classes.add("com.cz.kafka.interceptor.CounterInterceptor");
        props.put(ProducerConfig.INTERCEPTOR_CLASSES_CONFIG, classes);
        //创建生产者
        KafkaProducer<String, String> producer = new KafkaProducer<>(props);
        //发送数据
        for (int i = 0; i < 10; i++) {
            producer.send(new ProducerRecord<>("charges", i + ",female,25.84,0,no,northwest,28923.13692"));
        }
        //关闭
        producer.close();
    }
}