Java KafkaException:类不是org.apache.kafka.common.serialization.Deserializer的实例

我想实现Kafka producer，它发送和接收Java序列化对象。我试过这个：

制作人：

部署生产者时，在部署过程中出现错误：

原因：org.apache.kafka.common.KafkaException:class org.engine.plugin.transactions.factory.SaleResponseFactory不是org.apache.kafka.common.serialization.Deserializer的实例

自定义对象

import org.apache.kafka.common.serialization.Serializer;

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class SaleRequestFactory implements Serializable, Serializer {

    private static final long serialVersionUID = 1744050117179344127L;
    
    private int id;

    @Override
    public byte[] serialize(String s, Object o) {
        return new byte[0];
    }
}

导入org.apache.kafka.common.serialization.Deserializer； @吸气剂 @塞特 @诺尔格构装师 @AllArgsConstructor @生成器（toBuilder=true） 公共类SaleResponseFactory实现可序列化的反序列化程序{ 私有静态最终长serialVersionUID=1744050117179344127L； 私有字符串唯一\u id； @凌驾 公共对象反序列化（字符串s，字节[]字节）{ 返回null； } } 你知道我如何解决这个问题吗

编辑：我尝试了以下方法：

制作人：

自定义对象

你知道我如何解决这个问题吗

编辑： 我设法实施了这些改进：

制作人：

自定义对象

---

您知道如何解决这个问题吗？

KEY\u DESERIALIZER\u CLASS\u CONFIG是一个将网络值反序列化为适当Java类的类。你提供的课程没有做到这一点

---

在大多数情况下，使用StringDeserializer。为factory属性指定适当的反序列化程序。

您使用的类型与序列化对象的类型不同。不知道你为什么要这么做。您可以将反序列化更新为如下内容

public class SaleRequestFactoryDeserializer implements Serializable, Deserializer<SaleRequestFactory> {

     @Override
     public SaleRequestFactory deserialize(String topic, byte[] data) {
      ...
        saleRequestFactory = (SaleRequestFactory) in.readObject();

    }
}

---

这也意味着您的序列化没有按预期工作。在尝试强制转换之前，请确保您拥有有效的负载。

这是否回答了您的问题？您应该将正在序列化的对象与实际的序列化程序类分开，并且它们不需要称为“工厂”，请向我展示代码示例，好吗？您已经有了它，但是修复命名

SaleRequestSerializer实现org.apache.kafka.common.serialization.Serializer

。。。我的观点是，例如，你的ProducerFactory不应该“发送”你的序列化程序，所以有一个单独的类

ProducerFactory

I更新了代码。现在我得到了由以下原因引起的

：org.apache.kafka.common.KafkaException:class org.engine.plugin.transactions.factory.SaleResponseFactory不是org.apache.kafka.common.serialization.Deserializer的实例

“在大多数情况下，使用的是StringDeserializer。”-对于没有toString实现的自定义对象，这是错误的。您需要使用Kafka驱动程序提供的反序列化程序，或者使类实现org.apache.Kafka.common.serialization.Deserializer。有关此接口的文档，请参阅。这是解决方案。还有一个问题：我是否需要像这样添加刷新：

ObjectOutputStream outputStream=newobjectoutputstream（out）；outputStream.writeObject（数据）；out.flush（）；out.close（）以防止内存泄漏？
@EnableKafka
@Configuration
public class KafkaConsumerConfig {

    @Value(value = "${kafka.bootstrapAddress}")
    private String bootstrapAddress;

    private String groupId = "test";

    @Bean
    public ConsumerFactory<String, SaleResponseFactory> consumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactory.class);
        return new DefaultKafkaConsumerFactory<>(props);
    }

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

    @KafkaListener(topics = "tp-sale")
public SaleResponseFactory transactionElavonAuthorizeProcess(@Payload SaleRequestFactory tf, @Headers MessageHeaders headers) throws Exception {

    System.out.println(tf.getId());

    SaleResponseFactory resObj = new SaleResponseFactory();
    resObj.setUnique_id("123123");

    return resObj;
}

import org.apache.kafka.common.serialization.Serializer;

@Getter
@Setter
@NoArgsConstructor
@AllArgsConstructor
@Builder(toBuilder = true)
public class SaleRequestFactory implements Serializable, Serializer {

    private static final long serialVersionUID = 1744050117179344127L;
    
    private int id;

    @Override
    public byte[] serialize(String s, Object o) {
        return new byte[0];
    }
}

@Configuration
public class KafkaProducerConfig {

@Value(value = "${kafka.bootstrapAddress}")
private String bootstrapAddress;

@Bean
public ProducerFactory<String, SaleRequestFactory> saleRequestFactoryProducerFactory() {
    Map<String, Object> configProps = new HashMap<>();
    configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
    configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
    configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, SaleRequestFactorySerializer.class);
    return new DefaultKafkaProducerFactory<>(configProps);
}

@Bean
public ProducerFactory<String, String> producerFactory() {
    Map<String, Object> configProps = new HashMap<>();
    configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
    return new DefaultKafkaProducerFactory<>(configProps);
}


@Bean
public KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate() {
    return new KafkaTemplate<>(saleRequestFactoryProducerFactory());
}

@Bean
public KafkaTemplate<String, String> kafkaTemplate() {
    return new KafkaTemplate<>(producerFactory());
}

@Autowired
private KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate;

private static String topic = "tp-sale";

private void perform(){

    SaleRequestFactory obj = new SaleRequestFactory();
    obj.setId(100);

    ListenableFuture<SendResult<String, SaleRequestFactory>> send = saleRequestFactoryKafkaTemplate.send(topic, obj);
}

@EnableKafka
@Configuration
public class KafkaConsumerConfig {

    @Value(value = "${kafka.bootstrapAddress}")
    private String bootstrapAddress;

    private String groupId = "test";

    @Bean
    public ConsumerFactory<String, SaleResponseFactory> consumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactoryDeserializer.class);
        return new DefaultKafkaConsumerFactory<>(props);
    }

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

    @KafkaListener(topics = "tp-sale")
public SaleResponseFactory transactionElavonAuthorizeProcess(@Payload SaleRequestFactory tf, @Headers MessageHeaders headers) throws Exception {

    System.out.println(tf.getId());

    SaleResponseFactory resObj = new SaleResponseFactory();
    resObj.setUnique_id("123123");

    return resObj;
}

    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @Builder(toBuilder = true)
    public class SaleRequestFactory implements Serializable{
    
        private static final long serialVersionUID = 1744050117179344127L;
        
        private int id;
    }

public class SaleRequestFactorySerializer implements Serializable, Serializer<SaleRequestFactory> {

    @Override
    public byte[] serialize(String topic, SaleRequestFactory data) {
        // convert data to byte[]
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        try
        {
            ObjectOutputStream outputStream = new ObjectOutputStream(out);
            outputStream.writeObject(data);
            out.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        return out.toByteArray();
    }
}


    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @Builder(toBuilder = true)
    public class SaleResponseFactory implements Serializable{
    
        private static final long serialVersionUID = 1744050117179344127L;
    
        private String unique_id;
    }

public class SaleResponseFactoryDeserializer implements Serializable, Deserializer<SaleResponseFactory> {

    @Override
    public SaleResponseFactory deserialize(String topic, byte[] data) {
        // convert data to SaleResponseFactory
        SaleResponseFactory saleResponseFactory = null;
        try
        {
            ByteArrayInputStream bis = new ByteArrayInputStream(data);
            ObjectInputStream in = new ObjectInputStream(bis);
            saleResponseFactory = (SaleResponseFactory) in.readObject();
            in.close();
        }
        catch (IOException | ClassNotFoundException e)
        {
            e.printStackTrace();
        }
        return saleResponseFactory;
    }
}

Caused by: org.apache.kafka.common.errors.SerializationException: Error deserializing key/value for partition tp-sale-0 at offset 0. If needed, please seek past the record to continue consumption.
Caused by: java.lang.ClassCastException: null
21:27:51.152 [org.springframework.kafka.KafkaListenerEndpointContainer#0-0-C-1] DEBUG KafkaMessageListenerContainer$ListenerConsumer[debug:296] - Commit list: {}
21:27:51.153 [org.springframework.kafka.KafkaListenerEndpointContainer#0-0-C-1] ERROR KafkaMessageListenerContainer$ListenerConsumer[error:149] - Consumer exception
java.lang.IllegalStateException: This error handler cannot process 'SerializationException's directly; please consider configuring an 'ErrorHandlingDeserializer' in the value and/or key deserializer
        at org.springframework.kafka.listener.SeekUtils.seekOrRecover(SeekUtils.java:145)
        at org.springframework.kafka.listener.SeekToCurrentErrorHandler.handle(SeekToCurrentErrorHandler.java:103)
        at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.handleConsumerException(KafkaMessageListenerContainer.java:1265)
        at org.springframework.kafka.listener.KafkaMessageListenerContainer$ListenerConsumer.run(KafkaMessageListenerContainer.java:1022)
        at java.base/java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:515)
        at java.base/java.util.concurrent.FutureTask.run(FutureTask.java:264)
        at java.base/java.lang.Thread.run(Thread.java:835)
Caused by: org.apache.kafka.common.errors.SerializationException: Error deserializing key/value for partition tp-sale-0 at offset 0. If needed, please seek past the record to continue consumption.
Caused by: java.lang.ClassCastException: null

@Configuration
public class KafkaProducerConfig {

@Value(value = "${kafka.bootstrapAddress}")
private String bootstrapAddress;

@Bean
public ProducerFactory<String, SaleRequestFactory> saleRequestFactoryProducerFactory() {
    Map<String, Object> configProps = new HashMap<>();
    configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
    configProps.put(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG, StringSerializer.class);
    configProps.put(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG, SaleRequestFactorySerializer.class);
    return new DefaultKafkaProducerFactory<>(configProps);
}

@Bean
public ProducerFactory<String, String> producerFactory() {
    Map<String, Object> configProps = new HashMap<>();
    configProps.put(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
    return new DefaultKafkaProducerFactory<>(configProps);
}


@Bean
public KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate() {
    return new KafkaTemplate<>(saleRequestFactoryProducerFactory());
}

@Bean
public KafkaTemplate<String, String> kafkaTemplate() {
    return new KafkaTemplate<>(producerFactory());
}

@Autowired
private KafkaTemplate<String, SaleRequestFactory> saleRequestFactoryKafkaTemplate;

private static String topic = "tp-sale";

private void perform(){

    SaleRequestFactory obj = new SaleRequestFactory();
    obj.setId(100);

    ListenableFuture<SendResult<String, SaleRequestFactory>> send = saleRequestFactoryKafkaTemplate.send(topic, obj);
}

@EnableKafka
@Configuration
public class KafkaConsumerConfig {

    @Value(value = "${kafka.bootstrapAddress}")
    private String bootstrapAddress;

    private String groupId = "test";

    @Bean
    public ConsumerFactory<String, SaleResponseFactory> consumerFactory() {
        Map<String, Object> props = new HashMap<>();
        props.put(ConsumerConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapAddress);
        props.put(ConsumerConfig.GROUP_ID_CONFIG, groupId);
        props.put(ConsumerConfig.KEY_DESERIALIZER_CLASS_CONFIG, StringDeserializer.class);
        props.put(ConsumerConfig.VALUE_DESERIALIZER_CLASS_CONFIG, SaleResponseFactoryDeserializer.class);
        return new DefaultKafkaConsumerFactory<>(props);
    }

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

    @KafkaListener(topics = "tp-sale")
public SaleResponseFactory transactionElavonAuthorizeProcess(@Payload SaleRequestFactory tf, @Headers MessageHeaders headers) throws Exception {

    System.out.println(tf.getId());

    SaleResponseFactory resObj = new SaleResponseFactory();
    resObj.setUnique_id("123123");

    return resObj;
}

    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @Builder(toBuilder = true)
    public class SaleRequestFactory implements Serializable{
    
        private static final long serialVersionUID = 1744050117179344127L;
        
        private int id;
    }

public class SaleRequestFactorySerializer implements Serializable, Serializer<SaleRequestFactory> {

    @Override
    public byte[] serialize(String topic, SaleRequestFactory data) {
        // convert data to byte[]
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        try
        {
            ObjectOutputStream outputStream = new ObjectOutputStream(out);
            outputStream.writeObject(data);
            out.close();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }

        return out.toByteArray();
    }
}


    @Getter
    @Setter
    @NoArgsConstructor
    @AllArgsConstructor
    @Builder(toBuilder = true)
    public class SaleResponseFactory implements Serializable{
    
        private static final long serialVersionUID = 1744050117179344127L;
    
        private String unique_id;
    }

public class SaleResponseFactoryDeserializer implements Serializable, Deserializer<SaleResponseFactory> {

    @Override
    public SaleResponseFactory deserialize(String topic, byte[] data) {
        // convert data to SaleResponseFactory
        SaleResponseFactory saleResponseFactory = null;
        try
        {
            ByteArrayInputStream bis = new ByteArrayInputStream(data);
            ObjectInputStream in = new ObjectInputStream(bis);
            saleResponseFactory = (SaleResponseFactory) in.readObject();
            in.close();
        }
        catch (IOException | ClassNotFoundException e)
        {
            e.printStackTrace();
        }
        return saleResponseFactory;
    }
}

13:03:53.675 [org.springframework.kafka.KafkaListenerEndpointContainer#0-0-C-1] DEBUG RecordMessagingMessageListenerAdapter[debug:296] - Listener method returned result [org.factory.SaleResponseFactory@69c400ab] - generating response message for it
13:03:53.675 [org.springframework.kafka.KafkaListenerEndpointContainer#0-0-C-1] DEBUG RecordMessagingMessageListenerAdapter[debug:296] - No replyTopic to handle the reply: org.factory.SaleResponseFactory@69c400ab

public class SaleRequestFactoryDeserializer implements Serializable, Deserializer<SaleRequestFactory> {

     @Override
     public SaleRequestFactory deserialize(String topic, byte[] data) {
      ...
        saleRequestFactory = (SaleRequestFactory) in.readObject();

    }
}

java.lang.ClassCastException: null