黑猴子的家：Kafka 拦截器应用案例

Code -> GitHub

https://github.com/liufengji/kafka_api.git

1、需求

实现一个简单的双interceptor组成的拦截链。

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。

2、拦截器一

增加时间戳拦截器

import java.util.Map;
import org.apache.kafka.clients.producer.ProducerInterceptor;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;

public class TimeInterceptor implements ProducerInterceptor<String, String> {

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

    }

    @Override
    public ProducerRecord<String, String> 
                                  onSend(ProducerRecord<String, String> record) {
        // 创建一个新的record，把时间戳写入消息体的最前部
        return new ProducerRecord(record.topic(), record.partition(),
                record.timestamp(), record.key(),
                System.currentTimeMillis() + "," + record.value().toString());
    }

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

    }

    @Override
    public void close() {

    }
}

3、拦截器二

统计发送消息成功和发送失败消息数，并在producer关闭时打印这两个计数器

import java.util.Map;
import org.apache.kafka.clients.producer.ProducerInterceptor;
import org.apache.kafka.clients.producer.ProducerRecord;
import org.apache.kafka.clients.producer.RecordMetadata;

public class CounterInterceptor implements ProducerInterceptor<String, String>{
    private int errorCounter = 0;
    private int successCounter = 0;

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

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

    @Override
    public void onAcknowledgement(RecordMetadata metadata, Exception exception) {
        // 统计成功和失败的次数
        if (exception == null) {
            successCounter++;
        } else {
            errorCounter++;
        }
    }

    @Override
    public void close() {
        // 保存结果
        System.out.println("Successful sent: " + successCounter);
        System.out.println("Failed sent: " + errorCounter);
    }
}

4、producer主方法程序

import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import org.apache.kafka.clients.producer.KafkaProducer;
import org.apache.kafka.clients.producer.Producer;
import org.apache.kafka.clients.producer.ProducerConfig;
import org.apache.kafka.clients.producer.ProducerRecord;

public class InterceptorProducer {

    public static void main(String[] args) throws Exception {
        // 1 设置配置信息
        Properties props = new Properties();
        props.put("bootstrap.servers", "node1:9092");
        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");
        
        // 2 构建拦截链
        List<String> interceptors = new ArrayList<>();
        interceptors.add("com.victor.kafka.interceptor.TimeInterceptor");
        interceptors.add("com.victor.kafka.interceptor.CounterInterceptor"); 
        props.put(ProducerConfig.INTERCEPTOR_CLASSES_CONFIG, interceptors);
         
        String topic = "first";
        Producer<String, String> producer = new KafkaProducer<>(props);
        
        // 3 发送消息
        for (int i = 0; i < 10; i++) {
            
            ProducerRecord<String, String> record = 
                                    new ProducerRecord<>(topic, "message" + i);
            producer.send(record);
        }
         
        // 4 一定要关闭producer，这样才会调用interceptor的close方法
        producer.close();
    }
}

5、在kafka上启动消费者，然后运行客户端Java程序

[[email protected] kafka]$ bin/kafka-console-consumer.sh \
--zookeeper node1:2181 \
--from-beginning \
--topic first

1501904047034,message0
1501904047225,message1
1501904047230,message2
1501904047234,message3
1501904047236,message4
1501904047240,message5
1501904047243,message6
1501904047246,message7
1501904047249,message8
1501904047252,message9

6、观察java平台控制台输出数据

Successful sent: 10
Failed sent: 0