January 2018
Beginner to intermediate
234 pages
7h 8m
Chinese
Content preview from Kafka权威指南
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72
｜
第
4
章
包的一部分，属于
Kafka
核心模块。它们分别被叫作
SimpleConsumer（简单消费者，实际
上也不是那么简单，它们是对
Kafka API
的轻度包装，可以用于从特定的分区和偏移量开
始读取消息）和高级消费者。高级消费者指的就是 ZookeeperConsumerConnector，它有点
像现在的消费者，有消费者群组，有分区再均衡，不过它使用
Zookeeper
来管理消费者群
组，并不具备提交偏移量和再均衡的可操控性。
因为现在的消费者同时支持以上两种行为，并且为开发人员提供了更高的可靠性和可操控
性，所以我们不打算讨论旧版
API
。如果你想使用它们，那么请三思，如果确定要使用，
可以从
Kafka
文档中了解更多的信息。
4.13
总结
我们在本章开头解释了
Kafka
消费者群组概念，消费者群组支持多个消费者从主题上读取
消息。在介绍完概念之后，我们又给出了一个消费订阅主题并持续读取消息的例子。然后
介绍了一些重要的消费者配置参数以及它们对消费者行为的影响。我们用一大部分内容解
释偏移量以及消费者是如何管理偏移量的。了解消费者提交偏移量的方式有助更好地使用
消费者客户端，所以我们介绍了几种不同的偏移量提交方式。然后又探讨了消费者
API
的
其他话题，比如如何处理再均衡以及如何关闭消费者。
最后，我们介绍了反序列化器，消费者客户端使用反序列化器将保存在
Kafka
里的字节转
换成应用程序可以处理的
Java
对象。我们主要介绍了
Avro
反序列化器，虽然有很多可用
的反序列化器，但在
Kafka
里，
Avro
是最为常用的一个。 ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.