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。

增加时间戳拦截器

package com.interceptor;
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());
    }
    //收到ack以后调用这个方法
    @Override
    public void onAcknowledgement(RecordMetadata metadata, Exception exception) {
    }
    //关闭producer时候调用这个方法
    @Override
    public void close() {
    }
}

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

package com.interceptor;
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);
    }
}

生产者主程序

package com.interceptor;
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", "zjj101:9092");
        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.interceptor.TimeInterceptor");
        interceptors.add("com.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();
    }
}

消费者主程序

package com.consumer;
import org.apache.kafka.clients.consumer.ConsumerRecord;
import org.apache.kafka.clients.consumer.ConsumerRecords;
import org.apache.kafka.clients.consumer.KafkaConsumer;
import java.util.Arrays;
import java.util.Properties;
public class CustomConsumer {
    public static void main(String[] args) {
        Properties props = new Properties();
        props.put("bootstrap.servers", "zjj101:9092");
        props.put("group.id", "test");
//enable.auto.commit：是否开启自动提交offset功能
        props.put("enable.auto.commit", "true");
//auto.commit.interval.ms：自动提交offset的时间间隔
        props.put("auto.commit.interval.ms", "1000");
        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);
        //订阅 名字为 first的  topic ,可以订阅好几个topic
        consumer.subscribe(Arrays.asList("first"));
        while (true) {
            ConsumerRecords<String, String> records = consumer.poll(100);
            for (ConsumerRecord<String, String> record : records) {
                System.out.printf("offset = %d, key = %s, value = %s%n", record.offset(), record.key(), record.value());
                //输出: offset = 400, key = 0, value = 0
            }
        }
    }
}

如何测试

启动一个消费者,然后运行这个生产者 就能看到效果了.