看懂Android的Build number

先前一直觉得很奇怪，为什么Android的各个版本代号为什么会起那么些奇怪的名字，什么Froyo （2.2），Gingerbread（2.3），Ice Cream Sandwich（4.0），Jelly Bean （4.1）。原来基本按着代号的第一个单词的首字母的顺序来的。最初的代号从D （Donut）开始，当然中间也有些跳跃，比如H就没有出现。
要读懂Buildnumber也得掌握google的命令规则才行。

• First letter = release family, e.g. F is Froyo

• Second letter = branch code that allows Google to identify the exact code branch that the build was made from, and R is by convention the primary release branch

• Third letter and the two numbers = date code. The letter counts quarters, with A being Q1 2009. Therefore, F is Q2 2010. The two digits count days within the quarter, so F85 is June 24 2010. 

• Last letter = individual versions related to the same date code, sequentially starting with A; A is actually implicit and usually omitted for brevity.

更多细节：http://source.android.com/source/build-numbers.html