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GH-3807: Necessity of KafkaHandler on single method class #3865

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Merged
merged 6 commits into from
Apr 29, 2025
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GH-3807: Necessity of KafkaHandler on single method class #3865

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spring-projectsGH-3807: Necessity of KafkaHandler on single method class
chickenchickenlove Apr 24, 2025
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Addressing PR review
chickenchickenlove Apr 25, 2025
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chickenchickenlove Apr 25, 2025
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Revert to a52faccd
chickenchickenlove Apr 27, 2025
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chickenchickenlove Apr 27, 2025
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chickenchickenlove Apr 28, 2025
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5 changes: 4 additions & 1 deletion ...tora/modules/ROOT/pages/kafka/receiving-messages/class-level-kafkalistener.adoc
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Expand Up @@ -2,6 +2,10 @@
= `@KafkaListener` on a Class

When you use `@KafkaListener` at the class-level, you must specify `@KafkaHandler` at the method level.
If you do not use `@KafkaHandler`, no method will be used as a listener.

IMPORTANT: This is because a class annotated at the class-level may be extended or inherited in various ways.
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While I'm not disagree with the info, it feels a bit awkward.
Even the first new sentence is confusing.

How about to have a text like this after that "you must specify @KafkaHandler ":

If no `@KafkaHandler` on any methods of this class or its sub-classes, the framework will reject such a configuration.
The `@KafkaHandler` annotation is required for explicit and concise purpose of the method.
Otherwise it is hard to make a decision about this or other method without extra restrictions.

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Nice! thanks for fixing it. 🙇‍♂️
I updated.


When messages are delivered, the converted message payload type is used to determine which method to call.
The following example shows how to do so:

Expand Down Expand Up @@ -58,4 +62,3 @@ void listen(Object in, @Header(KafkaHeaders.RECORD_METADATA) ConsumerRecordMetad
...
}
----