java - Kafka Streams 物化存储构建错误

Question

我正在尝试在这里构建 Materialized.as DSL 代码:https://kafka.apache.org/11/javadoc/org/apache/kafka/streams/state/Stores.html

但我收到错误

incompatible types: org.apache.kafka.common.serialization.Serde<java.lang.Long> cannot be converted to org.apache.kafka.common.serialization.Serde<java.lang.Object>

上线

.withKeySerde(Serdes.Long())

有人知道这里可能出了什么问题吗？

final StreamsBuilder builder = new StreamsBuilder();

   KeyValueBytesStoreSupplier storeSupplier = Stores.inMemoryKeyValueStore("mystore");
   KTable<Long,String> dataStore = builder.table(
     "example_stream",
     Materialized.as(storeSupplier)
             .withKeySerde(Serdes.Long())
             .withValueSerde(Serdes.String()));

Answer 1

问题是 builder.table不知道默认为 <Object,Object> 的泛型类型。后来，Serde 类型不匹配。您需要指定类型，例如

KTable<Long,String> dataStore = builder.<Long,String>table(
    "example_stream",
    Materialized.as(storeSupplier)
        .withKeySerde(Serdes.Long())
        .withValueSerde(Serdes.String()));