SpringBoot-kafka序列化使用 Avro

【需求】：生产者发送数据至 kafka 序列化使用 Avro，消费者通过 Avro 进行反序列化，并将数据通过 MyBatis 存入数据库。

一、Pom

---

【1】Apache Avro 1.8；【2】Spring Kafka 1.2；【3】Spring Boot 1.5；【4】Maven 3.5；

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.codenotfound</groupId>
  <artifactId>spring-kafka-avro</artifactId>
  <version>0.0.1-SNAPSHOT</version>

  <name>spring-kafka-avro</name>
  <description>Spring Kafka - Apache Avro Serializer Deserializer Example</description>
  <url>https://www.codenotfound.com/spring-kafka-apache-avro-serializer-deserializer-example.html</url>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.4.RELEASE</version>
  </parent>

  <properties>
    <java.version>1.8</java.version>

    <spring-kafka.version>1.2.2.RELEASE</spring-kafka.version>
    <avro.version>1.8.2</avro.version>

  </properties>

  <dependencies>
    <!-- spring-boot -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter</artifactId>
    </dependency>
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-test</artifactId>
      <scope>test</scope>
    </dependency>
    <!-- spring-kafka -->
    <dependency>
      <groupId>org.springframework.kafka</groupId>
      <artifactId>spring-kafka</artifactId>
      <version>${spring-kafka.version}</version>
    </dependency>
    <dependency>
      <groupId>org.springframework.kafka</groupId>
      <artifactId>spring-kafka-test</artifactId>
      <version>${spring-kafka.version}</version>
      <scope>test</scope>
    </dependency>
    <!-- avro -->
    <dependency>
      <groupId>org.apache.avro</groupId>
      <artifactId>avro</artifactId>
      <version>${avro.version}</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <!-- spring-boot-maven-plugin -->
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
      <!-- avro-maven-plugin -->
      <plugin>
        <groupId>org.apache.avro</groupId>
        <artifactId>avro-maven-plugin</artifactId>
        <version>${avro.version}</version>
        <executions>
          <execution>
            <phase>generate-sources</phase>
            <goals>
              <goal>schema</goal>
            </goals>
            <configuration>
              <sourceDirectory>${project.basedir}/src/main/resources/avro/</sourceDirectory>
              <outputDirectory>${project.build.directory}/generated/avro</outputDirectory>
            </configuration>
          </execution>
        </executions>
      </plugin>
    </plugins>
  </build>
</project>

二、Avro 文件

---

【1】Avro 依赖于由使用JSON定义的原始类型组成的架构。对于此示例，我们将使用Apache Avro入门指南中的“用户”模式，如下所示。该模式存储在src / main / resources / avro下的 user.avsc文件中。我这里使用的是 electronicsPackage.avsc。namespace 指定你生成 java 类时指定的 package 路径，name 表时生成的文件。

{"namespace": "com.yd.cyber.protocol.avro",
 "type": "record",
 "name": "ElectronicsPackage",
 "fields": [
     {"name":"package_number","type":["string","null"],"default": null},
     {"name":"frs_site_code","type":["string","null"],"default": null},
     {"name":"frs_site_code_type","type":["string","null"],"default":null},
     {"name":"end_allocate_code","type":["string","null"],"default": null},
     {"name":"code_1","type":["string","null"],"default": null},
     {"name":"aggregat_package_code","type":["string","null"],"default": null}
    ]
}

【2】Avro附带了代码生成功能，该代码生成功能使我们可以根据上面定义的“用户”模式自动创建Java类。一旦生成了相关的类，就无需直接在程序中使用架构。这些类可以使用 avro-tools.jar 或项目是Maven 项目，调用 Maven Projects 进行 compile 自动生成 electronicsPackage.java 文件：如下是通过 maven 的方式
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【3】这将导致生成一个 electronicsPackage.java 类，该类包含架构和许多**Builder**构造 electronicsPackage对象的方法。
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三、为 Kafka 主题生成 Avro消息

---

Kafka Byte 在其主题中存储和传输数组。但是，当我们使用 Avro对象时，我们需要在这些 Byte数组之间进行转换。在0.9.0.0版之前，Kafka Java API使用 Encoder/ Decoder接口的实现来处理转换，但是在新API中，这些已经被 Serializer/ Deserializer接口实现代替。Kafka附带了许多 内置（反）序列化器，但不包括Avro。为了解决这个问题，我们将创建一个 AvroSerializer类，该类Serializer专门为 Avro对象实现接口。然后，我们实现将``serialize() 主题名称和数据对象作为输入的方法，在本例中，该对象是扩展的 Avro对象 SpecificRecordBase。该方法将Avro对象序列化为字节数组并返回结果。这个类属于通用类，一次配置多次使用。

package com.yd.cyber.web.avro;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.Map;

import org.apache.avro.io.BinaryEncoder;
import org.apache.avro.io.DatumWriter;
import org.apache.avro.io.EncoderFactory;
import org.apache.avro.specific.SpecificDatumWriter;
import org.apache.avro.specific.SpecificRecordBase;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.serialization.Serializer;

/**
 *  avro序列化类
 * @author zzx
 * @creat 2020-03-11-19:17
 */
public class AvroSerializer<T extends SpecificRecordBase> implements Serializer<T> {
    @Override
    public void close() {}

    @Override
    public void configure(Map<String, ?> arg0, boolean arg1) {}

    @Override
    public byte[] serialize(String topic, T data) {
        if(data == null) {
            return null;
        }
        DatumWriter<T> writer = new SpecificDatumWriter<>(data.getSchema());
        ByteArrayOutputStream byteArrayOutputStream  = new ByteArrayOutputStream();
        BinaryEncoder binaryEncoder  = EncoderFactory.get().directBinaryEncoder(byteArrayOutputStream , null);
        try {
            writer.write(data, binaryEncoder);
            binaryEncoder.flush();
            byteArrayOutputStream.close();
        }catch (IOException e) {
            throw new SerializationException(e.getMessage());
        }
        return byteArrayOutputStream.toByteArray();
    }
}

四、AvroConfig 配置类

---

Avro 配置信息在 AvroConfig 配置类中，现在，我们需要更改，AvroConfig 开始使用我们的自定义 Serializer实现。这是通过将“ VALUE_SERIALIZER_CLASS_CONFIG”属性设置为 AvroSerializer该类来完成的。此外，我们更改了ProducerFactory 和KafkaTemplate 通用类型，使其指定 ElectronicsPackage 而不是 String。当我们有多个序列化的时候，这个配置文件需要多次需求，添加自己需要序列化的对象。

package com.yd.cyber.web.avro;

/**
 * @author zzx
 * @creat 2020-03-11-20:23
 */
@Configuration
@EnableKafka
public class AvroConfig {

    @Value("${spring.kafka.bootstrap-servers}")
    private String bootstrapServers;

    @Value("${spring.kafka.producer.max-request-size}")
    private String maxRequestSize;

    @Bean
    public Map<String, Object> avroProducerConfigs() {
        Map<String, Object> props = new HashMap<>();
        props.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ProducerConfig.MAX_REQUEST_SIZE_CONFIG, maxRequestSize);
        props.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
        props.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, AvroSerializer.class);
        return props;
    }

    @Bean
    public ProducerFactory<String, ElectronicsPackage> elProducerFactory() {
        return new DefaultKafkaProducerFactory<>(avroProducerConfigs());
    }

    @Bean
    public KafkaTemplate<String, ElectronicsPackage> elKafkaTemplate() {
        return new KafkaTemplate<>(elProducerFactory());
    }
}

五、通过 kafkaTemplate 发送消息

---

最后就是通过 Controller类调用 kafkaTemplate 的 send 方法接受一个Avro electronicsPackage对象作为输入。请注意，我们还更新了 kafkaTemplate 泛型类型。

package com.yd.cyber.web.controller.aggregation;

import com.yd.cyber.protocol.avro.ElectronicsPackage;
import com.yd.cyber.web.vo.ElectronicsPackageVO;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.kafka.core.KafkaTemplate;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;

/**
 * 

 * InnoDB free: 4096 kB 前端控制器
 * 
 *
 * @author zzx
 * @since 2020-04-19
 */
@RestController
@RequestMapping("/electronicsPackageTbl")
public class ElectronicsPackageController {

    //日誌
    private static final Logger log = LoggerFactory.getLogger(ElectronicsPackageController.class);

    @Resource
    private KafkaTemplate<String,ElectronicsPackage> kafkaTemplate;

    @GetMapping("/push")
    public void push(){
        ElectronicsPackageVO electronicsPackageVO = new ElectronicsPackageVO();
        electronicsPackageVO.setElectId(9);
        electronicsPackageVO.setAggregatPackageCode("9");
        electronicsPackageVO.setCode1("9");
        electronicsPackageVO.setEndAllocateCode("9");
        electronicsPackageVO.setFrsSiteCodeType("9");
        electronicsPackageVO.setFrsSiteCode("9");
        electronicsPackageVO.setPackageNumber("9");
        ElectronicsPackage electronicsPackage = new ElectronicsPackage();
        BeanUtils.copyProperties(electronicsPackageVO,electronicsPackage);
        //发送消息
        kafkaTemplate.send("Electronics_Package",electronicsPackage);
        log.info("Electronics_Package TOPIC 发送成功");
    }
}

六、从 Kafka主题消费 Avro消息反序列化

---

收到的消息需要反序列化为 Avro格式。为此，我们创建一个 AvroDeserializer 实现该 Deserializer接口的类。该 deserialize()方法将主题名称和Byte数组作为输入，然后将其解码回Avro对象。从 targetType类参数中检索需要用于解码的模式，该类参数需要作为参数传递给``AvroDeserializer构造函数。

package com.yd.cyber.web.avro;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Map;

import org.apache.avro.generic.GenericRecord;
import org.apache.avro.io.BinaryDecoder;
import org.apache.avro.io.DatumReader;
import org.apache.avro.io.DecoderFactory;
import org.apache.avro.specific.SpecificDatumReader;
import org.apache.avro.specific.SpecificRecordBase;
import org.apache.kafka.common.errors.SerializationException;
import org.apache.kafka.common.serialization.Deserializer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.xml.bind.DatatypeConverter;

/**
 *  avro反序列化
 * @author fuyx
 * @creat 2020-03-12-15:19
 */
public class AvroDeserializer<T extends SpecificRecordBase> implements Deserializer<T> {
    //日志系统
    private static final Logger LOGGER = LoggerFactory.getLogger(AvroDeserializer.class);

    protected final Class<T> targetType;

    public AvroDeserializer(Class<T> targetType) {
        this.targetType = targetType;
    }
    @Override
    public void close() {}

    @Override
    public void configure(Map<String, ?> arg0, boolean arg1) {}

    @Override
    public T deserialize(String topic, byte[] data) {
        try {
            T result = null;
            if(data == null) {
                return null;
            }
            LOGGER.debug("data='{}'", DatatypeConverter.printHexBinary(data));
            ByteArrayInputStream in = new ByteArrayInputStream(data);
            DatumReader<GenericRecord> userDatumReader = new SpecificDatumReader<>(targetType.newInstance().getSchema());
            BinaryDecoder decoder = DecoderFactory.get().directBinaryDecoder(in, null);
            result = (T) userDatumReader.read(null, decoder);
            LOGGER.debug("deserialized data='{}'", result);
            return result;
        } catch (Exception ex) {
            throw new SerializationException(
                    "Can't deserialize data '" + Arrays.toString(data) + "' from topic '" + topic + "'", ex);
        } finally {

        }
    }
}

七、反序列化的配置类

---

我将反序列化的配置和序列化的配置都放置在 AvroConfig 配置类中。在 AvroConfig 需要被这样更新了AvroDeserializer用作值“VALUE_DESERIALIZER_CLASS_CONFIG”属性。我们还更改了 ConsumerFactory 和 ConcurrentKafkaListenerContainerFactory通用类型，以使其指定ElectronicsPackage而不是 String。将 DefaultKafkaConsumerFactory 通过1个新的创造 AvroDeserializer 是需要 “User.class”作为构造函数的参数。需要使用Class targetType，AvroDeserializer 以将消费 byte[]对象反序列化为适当的目标对象（在此示例中为 ElectronicsPackage``类）。

@Configuration
@EnableKafka
public class AvroConfig {

    @Value("${spring.kafka.bootstrap-servers}")
    private String bootstrapServers;

    @Value("${spring.kafka.producer.max-request-size}")
    private String maxRequestSize;


    @Bean
    public Map<String, Object> consumerConfigs() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServers);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, AvroDeserializer.class);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, "avro");

        return props;
    }

    @Bean
    public ConsumerFactory<String, ElectronicsPackage> consumerFactory() {
        return new DefaultKafkaConsumerFactory<>(consumerConfigs(), new StringDeserializer(),
                new AvroDeserializer<>(ElectronicsPackage.class));
    }

    @Bean
    public ConcurrentKafkaListenerContainerFactory<String, ElectronicsPackage> kafkaListenerContainerFactory() {
        ConcurrentKafkaListenerContainerFactory<String, ElectronicsPackage> factory =
                new ConcurrentKafkaListenerContainerFactory<>();
        factory.setConsumerFactory(consumerFactory());

        return factory;
    }

}

八、消费者消费消息

---

消费者通过 @KafkaListener 监听对应的 Topic ，这里需要注意的是，网上直接获取对象的参数传的是对象，比如这里可能需要传入 ElectronicsPackage 类，但是我这样写的时候，error日志总说是返回序列化的问题，所以我使用 GenericRecord 对象接收，也就是我反序列化中定义的对象，是没有问题的。然后我将接收到的消息通过 mybatisplus 存入到数据库。

package com.zzx.cyber.web.controller.dataSource.intercompany;

import com.zzx.cyber.web.service.ElectronicsPackageService;
import com.zzx.cyber.web.vo.ElectronicsPackageVO;
import org.apache.avro.generic.GenericRecord;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeanUtils;
import org.springframework.kafka.annotation.KafkaListener;
import org.springframework.stereotype.Controller;

import javax.annotation.Resource;

/**
 * @desc:
 * @author: zzx
 * @creatdate 2020/4/1912:21
 */
@Controller
public class ElectronicsPackageConsumerController {

    //日志
    private static final Logger log  = LoggerFactory.getLogger(ElectronicsPackageConsumerController.class);

    //服务层
    @Resource
    private ElectronicsPackageService electronicsPackageService;
    /**
     * 扫描数据测试
     * @param genericRecordne
     */
    @KafkaListener(topics = {"Electronics_Package"})
    public void receive(GenericRecord genericRecordne) throws Exception {
        log.info("数据接收：electronicsPackage + "+  genericRecordne.toString());
        //业务处理类,mybatispuls 自动生成的类
        ElectronicsPackageVO electronicsPackageVO = new ElectronicsPackageVO();
        //将收的数据复制过来
        BeanUtils.copyProperties(genericRecordne,electronicsPackageVO);
        try {
            //落库
            log.info("数据入库");
            electronicsPackageService.save(electronicsPackageVO);
        } catch (Exception e) {
            throw new Exception("插入异常"+e);
        }
    }
}