Spring 雲 Kafka 流反序列化問題導致：java.lang.ClassCastException：ClassName 無法轉換為 ClassName

Question

我正在嘗試使用 spring 雲 Kafka 流活頁夾來使用來自該主題的 Avro 消息，但無法修復此 classCast 異常。

這是我的代碼：

  @Bean
  public Consumer<KStream<EventKey, Event>> process(){
    return input -> {
      input.peek(((key, value) -> logger.info("key value: "+ key.toString()+" value: "+value.toString())));
      logger.info("Received:" + input);
    };
  }

  @Bean
  public Serde<EventKey> avroInSerde(){
    final SpecificAvroSerde<EventKey> avroInSerde = new SpecificAvroSerde<>();
    Map<String, Object> serdeProperties = new HashMap<>();
    return avroInSerde;
  }

  @Bean
  public Serde<Event> avroOutSerde(){
    final SpecificAvroSerde<Event> avroOutSerde = new SpecificAvroSerde<>();
    return avroOutSerde;
  }

粘合劑：

spring:
  application:
    name: ${applicaton-name}
  cloud:
    stream:
      function:
        definition: process
      bindings:
        process-in-0:
          destination: ${input-topic-name}
          contentType: application/Avro
        process-out-0:
          destination: ${enriched-topic-name}
          contentType: application/Avro
      binding-retry-interval: 30
      kafka:
        streams:
          binder:
            brokers: ${kafka-broker}
            application-id: ${consumer-group-name}
            auto-create-topics: false
            auto-add-partitions: false
            configuration:
              processing.guarantee: at_least_once
              auto.offset.reset: earliest
              schema.registry.url: ${kafka-schema-registry}
              auto-register-schema: false
              security.protocol: SSL
              useNativeEncoding: true
              specific.avro.reader: true

錯誤：

Note that although incorrect Serdes are a common cause of error, the cast exception might have another cause (in user code, for example). For example, if a processor wires in a store, but casts the generics incorrectly, a class cast exception could be raised during processing, but the cause would not be wrong Serdes.
    at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:146)
    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:236)
    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:216)
    at org.apache.kafka.streams.processor.internals.ProcessorContextImpl.forward(ProcessorContextImpl.java:168)
    at org.apache.kafka.streams.processor.internals.SourceNode.process(SourceNode.java:96)
    at org.apache.kafka.streams.processor.internals.StreamTask.lambda$process$1(StreamTask.java:679)
    at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:836)
    at org.apache.kafka.streams.processor.internals.StreamTask.process(StreamTask.java:679)
    at org.apache.kafka.streams.processor.internals.TaskManager.process(TaskManager.java:1033)
    at org.apache.kafka.streams.processor.internals.StreamThread.runOnce(StreamThread.java:690)
    at org.apache.kafka.streams.processor.internals.StreamThread.runLoop(StreamThread.java:551)
    at org.apache.kafka.streams.processor.internals.StreamThread.run(StreamThread.java:510)
Caused by: java.lang.ClassCastException: EventKey cannot be cast to EventKey
    at org.apache.kafka.streams.kstream.internals.KStreamPeek$KStreamPeekProcessor.process(KStreamPeek.java:42)
    at org.apache.kafka.streams.processor.internals.ProcessorNode.lambda$process$2(ProcessorNode.java:142)
    at org.apache.kafka.streams.processor.internals.metrics.StreamsMetricsImpl.maybeMeasureLatency(StreamsMetricsImpl.java:836)
    at org.apache.kafka.streams.processor.internals.ProcessorNode.process(ProcessorNode.java:142)

我嘗試了此鏈接中提到的兩種方法https://spring.io/blog/2019/12/04/stream-processing-with-spring-cloud-stream-and-apache-kafka-streams-part-3-數據反序列化和序列化但沒有運氣

我錯過了什么嗎？

Answer 1

原因：java.lang.ClassCastException：EventKey 無法轉換為 EventKey

這可能是 class 加載程序問題； 解串器和消費者 bean 由不同的 class 加載器加載，您使用的是 Spring DevTools 嗎？

使用 spring-kafka，可以通過顯式創建消費者工廠並將反序列化器注入其中來避免這種情況。

使用 spring-cloud-stream（從版本 3.0.6 開始），您可以提供ClientFactoryCustomizer bean 並注入反序列化器實例（定義為@Bean ，以便它們使用相同的 class 加載器）。

或者，停止使用 DevTools。