让Kafka忽略对象的反序列化器并使用Kafka反序列化器

Question

I have a scenario where I have custom implemented deseralization to my class Item extends JsonDeserializer<User> which deserializes my object in one fashion.

While Kafka uses org.springframework.kafka.support.serializer.JsonDeserializer which is being overridden by this my new implementation.

How can I make my Kafka stop from using the custom implementation?

Custom Implemented code

public class ItemDeserializer extends JsonDeserializer<Item> { 

public ItemDeserializer() { 
    this(null); 
} 

public ItemDeserializer(Class<?> vc) { 
    super(vc); 
}

@Override
public Item deserialize(JsonParser jp, DeserializationContext ctxt) 
  throws IOException, JsonProcessingException {
    JsonNode node = jp.getCodec().readTree(jp);
    int id = (Integer) ((IntNode) node.get("id")).numberValue();
    String itemName = node.get("itemName").asText();
    int userId = (Integer) ((IntNode) node.get("createdBy")).numberValue();

    return new Item(id, itemName, new User(userId, null));
}}

And while using custom deserialiser, I call it like

ObjectMapper mapper = new ObjectMapper();
SimpleModule module = new SimpleModule();
module.addDeserializer(Item.class, new ItemDeserializer());
mapper.registerModule(module);

Item readValue = mapper.readValue(json, Item.class);

Item class is annotated with

@JsonDeserialize(using = ItemDeserializer.class)
public class Item {
   public int id;
   public String itemName;
   public User owner;
}

Kafka Configurations

consumer:
   deserializer:
      key.delegate.class: com.apache.kafka.common.serialization.stringDeserializer
      value.delegate.class: com.apache.kafka.common.serialization.JsonDeserializer
json:
   trusted:
      packages: com.package.to.item

Tried Searching for 3 days. This is my last resort on how to solve this problem

Answer 1

You're creating your own ObjectMapper. If you want to configure Spring-Kafka's ObjectMapper instance, then see here

make my Kafka stop from using the custom implementation

If you want to use the String Deserializer rather than JSON, then you don't need delegates . Simply set the deserializer directly

spring:
  kafka:
    consumer:
      key-deserializer: com.apache.kafka.common.serialization.StringDeserializer
      value-deserializer:  ...

Beyond this, unclear why you'd actually want strings that you'd need to deserialize yourself rather than consuming actual Item classes