android - 错误 : missing android-support-constraint-layout in AOSP but prebuilts/sdk/current/extras has it

Question

我的 Android 源代码库已经有两个 jar 文件 android-support-constraint-layout.jar 和 android-support-constraint-layout-solver.jar 分别在 prebuilts/sdk/current/extras/constraint-layout/libs/ 和 prebuilts/sdk/current/extras/constraint-layout-solver/。现在，我在 packages/app 中有一个应用程序，其中有一个 app/src/main/Android.mk:

LOCAL_STATIC_ANDROID_LIBRARIES := \
...
android-support-constraint-layout \
android-support-constraint-layout-solver

编译Android后仍然出现以下错误:

error: FirstApp (APPS android-x86) missing android-support-constraint-layout (JAVA_LIBRARIES android-x86)
You can set ALLOW_MISSING_DEPENDENCIES=true in your environment if this is intentional, but that may defer real problems until later in the build.
error: FirstApp (APPS android-x86) missing android-support-constraint-layout-solver (JAVA_LIBRARIES android-x86)

除了第一个，this link 中没有任何方法致力于在 AOSP 中添加约束布局。

Answer 1

我在 AOSP for Android-Oreo (v8.1) 的一个包中添加了约束布局。

下载constraint-layout (.aar) 和constraint-layout-solver (.jar)来自 Maven 存储库:https://mvnrepository.com/artifact/com.android.support.constraint/constraint-layout/1.0.2 , https://mvnrepository.com/artifact/com.android.support.constraint/constraint-layout-solver/1.0.2 将它们放在应用程序主目录 (packages/apps/AnotherFirstApp/) 的 libs/ 文件夹中。

在Android.mk中:

LOCAL_PATH:= $(call my-dir)
include $(CLEAR_VARS)

LOCAL_PACKAGE_NAME := AnotherFirstApp
LOCAL_MODULE_TAGS := optional
LOCAL_DEX_PREOPT := false

LOCAL_SRC_FILES := $(call all-java-files-under, src)

LOCAL_PROGUARD_FLAG_FILES := ../../../frameworks/support/design/proguard-rules.pro


ifeq ($(TARGET_BUILD_APPS),)
support_library_root_dir := frameworks/support
else
support_library_root_dir := prebuilts/sdk/current/support
endif

LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res \
                      $(support_library_root_dir)/design/res \
              $(support_library_root_dir)/v7/cardview/res \
              $(support_library_root_dir)/v7/recyclerview/res \
                      $(support_library_root_dir)/v7/appcompat/res

LOCAL_AAPT_FLAGS := \
    --auto-add-overlay \
    --extra-packages android.support.design \
    --extra-packages android.support.v7.cardview \
    --extra-packages android.support.constraint \
    --extra-packages android.support.v7.recyclerview \
    --extra-packages android.support.v7.appcompat

LOCAL_STATIC_JAVA_LIBRARIES := \
    android-support-design \
    android-support-v7-recyclerview \
    android-support-v4 \
    android-support-v7-cardview \
    android-support-v7-appcompat \
    constraint-layout-solver \

LOCAL_STATIC_JAVA_AAR_LIBRARIES := \
               constraint-layout

include $(BUILD_PACKAGE)

include $(CLEAR_VARS)

LOCAL_PREBUILT_STATIC_JAVA_LIBRARIES := \
           constraint-layout:libs/constraint-layout-1.0.2.aar \
           constraint-layout-solver:libs/constraint-layout-solver-1.0.2.jar 

include $(BUILD_MULTI_PREBUILT)

include $(call all-makefiles-under,$(LOCAL_PATH))

现在，没有问题了。该应用程序构建并运行良好。可能存在一个问题，因为没有以共享 jar 的方式添加约束求解器，以防其他应用程序也尝试使用此 jar。这需要通过在 framework 或 external 中添加此 jar 来处理。

我从以下博客中获得了帮助:

1. > https://sites.google.com/site/sbobovyc/home/Programming/a/creating-system-app
2. > http://saurabhsharma123k.blogspot.com/2017/03/add-and-use-external-library-or-jar.html
3. > https://kevinaboos.wordpress.com/2016/10/29/adding-an-external-library-or-jarfile-to-android-frameworks/
4. > https://github.com/BrahmaOS/brahmaos-packages-apps-GoodWeather/blob/master/Android.mk