从源码中查看当前android版本

1: 系统没有编译，从代码中查看当前版本

 vim build/core/version_defaults.mk

# Default versions for each TARGET_PLATFORM_VERSION
# TODO: PLATFORM_VERSION, PLATFORM_SDK_VERSION, etc. should be conditional
# on this

# This is the canonical definition of the platform version,
# which is the version that we reveal to the end user.
# Update this value when the platform version changes (rather
# than overriding it somewhere else).  Can be an arbitrary string.

# When you add a new PLATFORM_VERSION which will result in a new
# PLATFORM_SDK_VERSION please ensure you add a corresponding isAtLeast*
# method in the following java file:
# frameworks/support/compat/gingerbread/android/support/v4/os/BuildCompat.java

# When you change PLATFORM_VERSION for a given PLATFORM_SDK_VERSION
# please add that PLATFORM_VERSION as well as clean up obsolete PLATFORM_VERSION's
# in the following text file:
# cts/tests/tests/os/assets/platform_versions.txt
PLATFORM_VERSION.OPM1 := 8.1.0

 当前代码系统版本为 8.1.0

2 :   执行 配置选项，可以通过PLATFORM_VERSION查看到当前PLATFORM_VERSION版本号；

source build/envsetup.sh
lunch msm8953_64-userdebug