不多说，直接上干货！
一切来源于官网
http://kafka.apache.org/documentation/
Producers
生产者(Producers)
Producers publish data to the topics of their choice. The producer is responsible for choosing which record to assign to which partition within the topic. This can be done in a round-robin fashion simply to balance load or it can be done according to some semantic partition function (say based on some key in the record). More on the use of partitioning in a second!
生产者往某个Topic上发布消息。生产者也负责选择发布到Topic上的哪一个分区。最简单的方式从分区列表中轮流选择。
也可以根据某种算法依照权重选择分区。开发者负责如何选择分区的算法。