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spring-boot - SprintBoot kafka 值序列化器

问题描述

我有一个带有 apache kafka（一个开源流处理软件）的 SpringBoot 项目我有这个监听器

@KafkaListener(topics = "test")
public String consume(Hostel hostel) throws IOException {
}

这个序列化器

public class HostelSerializer implements Deserializer<Hostel> {

    private final ObjectMapper objectMapper;

    public InputRequestMessageSerializer(ObjectMapper objectMapper) {
        this.objectMapper = objectMapper;
    }

    @Override
    public void configure(Map<String, ?> map, boolean b) {
        this.configure(map,b);
    }

    @SneakyThrows
    @Override
    public Hostel deserialize(String s, byte[] bytes) {
        return objectMapper.readValue(bytes, Hostel.class);
    }

    @Override
    public void close() {
        this.close();
    }
}

在属性中：

spring:
    kafka:
        consumer:
          bootstrap-servers: localhost:9092
          group-id: group_id
          topics: test
          key-serializer: org.apache.kafka.common.serialization.StringSerializer
          value-serializer: com.kafka.config.HostelSerializer

但是当我收到一条消息时，我有这个错误

Caused by: org.springframework.messaging.converter.MessageConversionException: Cannot convert from [java.lang.String] 
to [com.message.Hostel] for GenericMessage [.....}]

查看日志它没有从属性中获取值：

2020-04-09 16:41:30,840 INFO  :  gid: trace= span= [main] o.a.k.c.consumer.ConsumerConfig ConsumerConfig values: 
    key.deserializer = class org.apache.kafka.common.serialization.StringDeserializer
    value.deserializer = class org.apache.kafka.common.serialization.StringDeserializer

标签： spring-bootapache-kafkakafka-consumer-apispring-kafkajsonserializer

解决方案

你混合反/序列化。由于您配置了消费者，因此您只需要使用正确的反序列化接口和实现：

kafka:
consumer:
  bootstrap-servers: localhost:9092
  group-id: group_id
  topics: test
  key-deserializer: org.apache.kafka.common.serialization.StringDeserializer
  value-deserializer: com.kafka.config.HostelDeserializer

... 和 ...

public class HostelDeserializer implements Deserializer<Hostel> { .. }

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