How to include .aar in AOSP with android.mk

Question

I need to build an application with android.mk in aosp build tree. I have a custom .arr lib with me, Which resides in the following folder apps/libs/mylib.aar

Anyone

Answer 1

I know I am too late, but still worth sharing this information. LOCAL_STATIC_JAVA_AAR_LIBRARIES support of AAPT2 was broken at some point. So even if you add your library as descibed above, resources from aar would not be linked.

from AOSP git history:

Oct 30, 2014 Add support for prebuilt AARs. Aars were unpacked into out/.../intermediates* dirs and linked to the aosp modules.

Dec 5, 2015 Support to build with AAPT2 As you can see in core/android_manifest.mk:26, linking unpacked aars was not necessary anymore, because AAPT2 supports linking directly into arrays.

But unfortunately they were not added as --extra-packages correctly.

The bug was fixed in android-p-preview-5.

If you are still developing for android 8 or 8.1 please add these changes manually or cherry-pick them in your tree. Worked perfectly for me.

UPD 2018-11-28

Exact steps to fix it for android 8.1 and earlier:

1) cherry-pick fix Dec 5, 2015 Support to build with AAPT2 from aosp

2) in build/core/prebuilt_internal.mk:593 add parameter --auto-add-overlay

$(my_res_package): PRIVATE_AAPT_FLAGS := --static-lib --no-static-lib-packages --auto-add-overlay

3) As RenderScript was refactored much later, you have to define your aar module explicitly:

include $(CLEAR_VARS)
LOCAL_MODULE := my-library-module
LOCAL_MODULE_TAGS := optional
LOCAL_SRC_FILES := my-library-module.aar
# Provide resources directory in order to compile them, enable AAPT2 for this module
LOCAL_RESOURCE_DIR := $(call intermediates-dir-for,JAVA_LIBRARIES,$(LOCAL_MODULE),,COMMON)/aar/res)
LOCAL_USE_AAPT2 := true
# if LOCAL_RENDERSCRIPT_TARGET_API >= 21, resources won't get compiled. Shouldn't affect anything else
LOCAL_RENDERSCRIPT_TARGET_API := 20
LOCAL_MODULE_CLASS := JAVA_LIBRARIES
LOCAL_MODULE_SUFFIX := $(COMMON_JAVA_PACKAGE_SUFFIX)
LOCAL_BUILT_MODULE_STEM := javalib.jar
LOCAL_UNINSTALLABLE_MODULE := true
include $(BUILD_PREBUILT)

Disclaimer: this is rather a hacky workaround that worked for me. Due to lack of time and urgent need to support older client versions, I may have missed some use cases.