如何使用avro二进制编码器编码/解码kafka消息?

zyfwsgd6  于 2021-06-07  发布在  Kafka
关注(0)|答案(5)|浏览(540)

我正在尝试使用avro来读取/写入Kafka的消息。有人举过使用avro二进制编码器编码/解码将放入消息队列的数据的例子吗?
我更需要阿夫罗的部分而不是Kafka的部分。或者,也许我应该换个方法?基本上,我正试图找到一个更有效的解决json空间问题的方法。刚才提到avro是因为它比json更紧凑。

v9tzhpje

v9tzhpje1#

更新的答案。
kafka有一个avro序列化程序/反序列化程序,其坐标为maven(sbt格式):

"io.confluent" % "kafka-avro-serializer" % "3.0.0"

将kafkavroserializer的示例传递到kafkaproducer构造函数中。
然后可以创建avro genericord示例,并将这些示例用作kafka producerrecord示例中的值,您可以使用kafkaproducer发送这些示例。
在kafka消费端,您使用kafkaavrodeserializer和kafkaconsumer。

mutmk8jj

mutmk8jj2#

我终于想起问Kafka的邮件列表,并得到了以下答案,这是完美的工作。
是的,您可以以字节数组的形式发送消息。如果您查看message类的构造函数,您将看到-
def this(字节:数组[byte])
现在,看看producer send()api-
def send(producerdata:producerdata[k,v]*)
您可以将v设置为message类型,将k设置为您想要的密钥类型。如果您不关心使用键进行分区,那么也将其设置为消息类型。
谢谢,内哈

r6l8ljro

r6l8ljro3#

代替avro,您还可以简单地考虑压缩数据;使用gzip(良好的压缩,更高的cpu)或lzf或snappy(更快,更慢的压缩)。
或者还有一种微笑二进制json,由jackson在java中支持(使用此扩展):它是紧凑的二进制格式,比avro更易于使用:

ObjectMapper mapper = new ObjectMapper(new SmileFactory());
byte[] serialized = mapper.writeValueAsBytes(pojo);
// or back
SomeType pojo = mapper.readValue(serialized, SomeType.class);

基本上与json相同的代码,只是传递了不同的格式工厂。从数据大小的Angular 来看,smile和avro是否更紧凑取决于用例的细节;但两者都比json更紧凑。
这样做的好处是,使用json和smile,使用相同的代码,只需使用pojo,就可以快速工作。与avro相比,avro要么需要生成代码,要么需要大量的手动代码来打包和解包 GenericRecord s。

goqiplq2

goqiplq24#

这是一个基本的例子。我没有尝试过多个分区/主题。
//示例生产者代码

import org.apache.avro.Schema;
import org.apache.avro.generic.GenericData;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.*;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificDatumWriter;
import org.apache.commons.codec.DecoderException;
import org.apache.commons.codec.binary.Hex;
import kafka.javaapi.producer.Producer;
import kafka.producer.KeyedMessage;
import kafka.producer.ProducerConfig;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.nio.charset.Charset;
import java.util.Properties;

public class ProducerTest {

    void producer(Schema schema) throws IOException {

        Properties props = new Properties();
        props.put("metadata.broker.list", "0:9092");
        props.put("serializer.class", "kafka.serializer.DefaultEncoder");
        props.put("request.required.acks", "1");
        ProducerConfig config = new ProducerConfig(props);
        Producer<String, byte[]> producer = new Producer<String, byte[]>(config);
        GenericRecord payload1 = new GenericData.Record(schema);
        //Step2 : Put data in that genericrecord object
        payload1.put("desc", "'testdata'");
        //payload1.put("name", "अasa");
        payload1.put("name", "dbevent1");
        payload1.put("id", 111);
        System.out.println("Original Message : "+ payload1);
        //Step3 : Serialize the object to a bytearray
        DatumWriter<GenericRecord>writer = new SpecificDatumWriter<GenericRecord>(schema);
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        BinaryEncoder encoder = EncoderFactory.get().binaryEncoder(out, null);
        writer.write(payload1, encoder);
        encoder.flush();
        out.close();

        byte[] serializedBytes = out.toByteArray();
        System.out.println("Sending message in bytes : " + serializedBytes);
        //String serializedHex = Hex.encodeHexString(serializedBytes);
        //System.out.println("Serialized Hex String : " + serializedHex);
        KeyedMessage<String, byte[]> message = new KeyedMessage<String, byte[]>("page_views", serializedBytes);
        producer.send(message);
        producer.close();

    }

    public static void main(String[] args) throws IOException, DecoderException {
        ProducerTest test = new ProducerTest();
        Schema schema = new Schema.Parser().parse(new File("src/test_schema.avsc"));
        test.producer(schema);
    }
}

//消费者代码示例
第1部分:使用者组代码:因为对于多个分区/主题,可以有多个使用者。

import kafka.consumer.ConsumerConfig;
import kafka.consumer.KafkaStream;
import kafka.javaapi.consumer.ConsumerConnector;

import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * Created by  on 9/1/15.
 */
public class ConsumerGroupExample {
   private final ConsumerConnector consumer;
   private final String topic;
   private ExecutorService executor;

   public ConsumerGroupExample(String a_zookeeper, String a_groupId, String a_topic){
      consumer = kafka.consumer.Consumer.createJavaConsumerConnector(
              createConsumerConfig(a_zookeeper, a_groupId));
      this.topic = a_topic;
   }

   private static ConsumerConfig createConsumerConfig(String a_zookeeper, String a_groupId){
       Properties props = new Properties();
       props.put("zookeeper.connect", a_zookeeper);
       props.put("group.id", a_groupId);
       props.put("zookeeper.session.timeout.ms", "400");
       props.put("zookeeper.sync.time.ms", "200");
       props.put("auto.commit.interval.ms", "1000");

       return new ConsumerConfig(props);
   }

    public void shutdown(){
         if (consumer!=null) consumer.shutdown();
        if (executor!=null) executor.shutdown();
        System.out.println("Timed out waiting for consumer threads to shut down, exiting uncleanly");
        try{
          if(!executor.awaitTermination(5000, TimeUnit.MILLISECONDS)){

          }
        }catch(InterruptedException e){
            System.out.println("Interrupted");
        }

    }

    public void run(int a_numThreads){
        //Make a map of topic as key and no. of threads for that topic
        Map<String, Integer> topicCountMap = new HashMap<String, Integer>();
        topicCountMap.put(topic, new Integer(a_numThreads));
        //Create message streams for each topic
        Map<String, List<KafkaStream<byte[], byte[]>>> consumerMap = consumer.createMessageStreams(topicCountMap);
        List<KafkaStream<byte[], byte[]>> streams = consumerMap.get(topic);

        //initialize thread pool
        executor = Executors.newFixedThreadPool(a_numThreads);
        //start consuming from thread
        int threadNumber = 0;
        for (final KafkaStream stream : streams) {
            executor.submit(new ConsumerTest(stream, threadNumber));
            threadNumber++;
        }
    }
    public static void main(String[] args) {
        String zooKeeper = args[0];
        String groupId = args[1];
        String topic = args[2];
        int threads = Integer.parseInt(args[3]);

        ConsumerGroupExample example = new ConsumerGroupExample(zooKeeper, groupId, topic);
        example.run(threads);

        try {
            Thread.sleep(10000);
        } catch (InterruptedException ie) {

        }
        example.shutdown();
    }

}

第2部分:实际消费信息的个人消费者。

import kafka.consumer.ConsumerIterator;
import kafka.consumer.KafkaStream;
import kafka.message.MessageAndMetadata;
import org.apache.avro.Schema;
import org.apache.avro.generic.GenericRecord;
import org.apache.avro.generic.IndexedRecord;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.Decoder;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.commons.codec.binary.Hex;

import java.io.File;
import java.io.IOException;

public class ConsumerTest implements Runnable{

    private KafkaStream m_stream;
    private int m_threadNumber;

    public ConsumerTest(KafkaStream a_stream, int a_threadNumber) {
        m_threadNumber = a_threadNumber;
        m_stream = a_stream;
    }

    public void run(){
        ConsumerIterator<byte[], byte[]>it = m_stream.iterator();
        while(it.hasNext())
        {
            try {
                //System.out.println("Encoded Message received : " + message_received);
                //byte[] input = Hex.decodeHex(it.next().message().toString().toCharArray());
                //System.out.println("Deserializied Byte array : " + input);
                byte[] received_message = it.next().message();
                System.out.println(received_message);
                Schema schema = null;
                schema = new Schema.Parser().parse(new File("src/test_schema.avsc"));
                DatumReader<GenericRecord> reader = new SpecificDatumReader<GenericRecord>(schema);
                Decoder decoder = DecoderFactory.get().binaryDecoder(received_message, null);
                GenericRecord payload2 = null;
                payload2 = reader.read(null, decoder);
                System.out.println("Message received : " + payload2);
            }catch (Exception e) {
                e.printStackTrace();
                System.out.println(e);
            }
        }

    }

}

测试avro架构:

{
    "namespace": "xyz.test",
     "type": "record",
     "name": "payload",
     "fields":[
         {
            "name": "name", "type": "string"
         },
         {
            "name": "id",  "type": ["int", "null"]
         },
         {
            "name": "desc", "type": ["string", "null"]
         }
     ]
}

需要注意的重要事项是:
您将需要标准的kafka和avrojars来运行这个开箱即用的代码。
是非常重要的props.put(“serializer.class”,“kafka.serializer.defaultencoder”);大学教师 t use stringEncoder as that won 如果您将字节数组作为消息发送,则无法工作。
您可以将byte[]转换为十六进制字符串并发送该字符串,然后在使用者上将十六进制字符串重新转换为byte[],然后再转换为原始消息。
运行Zookeeper和经纪人如下所述:http://kafka.apache.org/documentation.html#quickstart 并创建一个名为“页面视图”或任何你想要的主题。
运行producertest.java,然后运行consumergroupexample.java,查看正在生成和使用的avro数据。

qmelpv7a

qmelpv7a5#

如果要从avro消息(Kafka部分已应答)获取字节数组,请使用二进制编码器:

GenericDatumWriter<GenericRecord> writer = new GenericDatumWriter<GenericRecord>(schema); 
    ByteArrayOutputStream os = new ByteArrayOutputStream(); 
    try {
        Encoder e = EncoderFactory.get().binaryEncoder(os, null); 
        writer.write(record, e); 
        e.flush(); 
        byte[] byteData = os.toByteArray(); 
    } finally {
        os.close(); 
    }

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