Spring kafka，ConsumerSeekAware接口，onPartitionsAssigned方法在重新平衡时调用

Question

ConsumerSeekAware接口，onPartitionsAssigned方法在重新平衡时调用。因为我想在初始化和重新平衡时寻找偏移量中的特定偏移量。我可以将consumerSeekAware用于这两个目的，还是应该使用ConsumerRebalanceListener进行重新平衡。请给出简单的答案，因为我还没有关于春天卡夫卡的深度知识。如果可以，请提供示例代码。谢谢

Answer 1

ConsumerSeekAware有这种方法：

/**
 * When using group management, called when partition assignments change.
 * @param assignments the new assignments and their current offsets.
 * @param callback the callback to perform an initial seek after assignment.
 */
void onPartitionsAssigned(Map<TopicPartition, Long> assignments, ConsumerSeekCallback callback);

从KafkaMessageListenerContainer.seekPartitions(Collection<TopicPartition> partitions, boolean idle)调用，然后从ConsumerRebalanceListener.onPartitionsAssigned()内部实现调用。最后一个有这个JavaDocs：

 * A callback method the user can implement to provide handling of customized offsets on completion of a successful
 * partition re-assignment. This method will be called after an offset re-assignment completes and before the
 * consumer starts fetching data.

所以，是的，在重新平衡期间始终会调用ConsumerSeekAware.onPartitionsAssigned()。顺便说一句，Apache Kafka没有initializing这样的状态。总是rebalancing - 经纪人处于等待状态，并在新消费者加入时开始重新平衡。