1、使用BUILD_PREBUILT遇到的坑
使用BUILD_PREBUILT，一些属性的值必须指定，否则会报错
错误一：
build/core/base_rules.mk:122: *** vendor/icetech/preinstall/app/FEMSYS_Registration: LOCAL_MODULE_CLASS must contain exactly one word, not "".
build/core/ninja.mk:163: recipe for target 'out/build-e6e907c624e25ada6d4d9f66c976c642.ninja' failed
make: *** [out/build-e6e907c624e25ada6d4d9f66c976c642.ninja] Error 1
make: Leaving directory '/mnt/disk/binn/Work/a40i/android'
#### make failed to build some targets (1 seconds) ####
需要指定LOCAL_MODULE_CLASS的值
错误二：
build/core/prebuilt.mk:88: *** missing separator.
build/core/ninja.mk:163: recipe for target 'out/build-e6e907c624e25ada6d4d9f66c976c642.ninja' failed
make: *** [out/build-e6e907c624e25ada6d4d9f66c976c642.ninja] Error 1
make: Leaving directory '/mnt/disk/binn/Work/a40i/android'
#### make failed to build some targets (1 seconds) ####
这个错误提示比较隐蔽，通过和其他一些demo对比，发现必须指定LOCAL_MODULE_PATH的值
成功执行的案例脚本：
LOCAL_PATH := $(call my-dir)
# 把apk中的lib库编译到out目录下
# 该脚本可以再优化，执行该脚本时，自动解压apk，然后把so编译到out目录下
$(foreach p, $(notdir $(wildcard $(LOCAL_PATH)/armeabi-v7a/*.so)), \
$(eval include $(CLEAR_VARS)) \
$(eval LOCAL_MODULE_TAGS := optional) \
$(eval LOCAL_SRC_FILES := armeabi-v7a/$(p)) \
$(eval LOCAL_MODULE := $(shell basename $(p))) \
$(eval LOCAL_MODULE_CLASS := SHARED_LIBRARIES) \
$(eval LOCAL_MODULE_SUFFIX := .so) \
$(eval LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)) \
$(eval include $(BUILD_PREBUILT)) \
)
# apk编译到out目录下
include $(CLEAR_VARS)
LOCAL_MODULE := FEMSYS_Registration
LOCAL_DEX_PREOPT := false
LOCAL_MODULE_TAGS := optional
LOCAL_SRC_FILES := $(LOCAL_MODULE).apk
LOCAL_CERTIFICATE := platform
LOCAL_MODULE_CLASS := APPS
LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
LOCAL_MODULE_PATH := $(TARGET_OUT)/app
LOCAL_MULTILIB :=both
LOCAL_SHARED_LIBRARIES := $(foreach p,$(wildcard $(LOCAL_PATH)/armeabi-v7a/*.so),$(patsubst %.so,%,$(shell basename $(p))))
include $(BUILD_PREBUILT)
优化版本：自动解压apk，更新so文件
LOCAL_PATH := $(call my-dir)
# configure
# ----------------------
APK_MODULE := FEMSYS_Registration
CPU_ARCH := armeabi-v7a
# ----------------------
$(eval APK_EXTRACT_ROOT := $(TARGET_OUT_INTERMEDIATES)/TEMP)
$(eval LIBS_DIR := $(APK_EXTRACT_ROOT)/$(APK_MODULE)/lib/$(CPU_ARCH))
$(shell mkdir -p $(APK_EXTRACT_ROOT))
$(shell rm -fr $(APK_EXTRACT_ROOT)/$(APK_MODULE))
# 下面该命令不要分开执行，每个shell执行都是一个子shell，会出现同步情况
# 可能前一个命令未执行完，后一个命令已开始，出现编译错误
$(shell rm -fr $(LOCAL_PATH)/$(CPU_ARCH); \
unzip $(LOCAL_PATH)/$(APK_MODULE).apk -d $(APK_EXTRACT_ROOT)/$(APK_MODULE) >> /dev/null; \
cp -fr $(LIBS_DIR) $(LOCAL_PATH)/$(CPU_ARCH) \
)
$(foreach p, $(notdir $(wildcard $(LOCAL_PATH)/$(CPU_ARCH)/*.so)), \
$(eval include $(CLEAR_VARS)) \
$(eval LOCAL_MODULE_TAGS := optional) \
$(eval LOCAL_SRC_FILES := $(CPU_ARCH)/$(p)) \
$(eval LOCAL_MODULE := $(shell basename $(p) .so)) \
$(eval LOCAL_MODULE_CLASS := SHARED_LIBRARIES) \
$(eval LOCAL_MODULE_SUFFIX := .so) \
$(eval LOCAL_MODULE_PATH := $(TARGET_OUT_SHARED_LIBRARIES)) \
$(eval include $(BUILD_PREBUILT)) \
)
include $(CLEAR_VARS)
LOCAL_MODULE := $(APK_MODULE)
LOCAL_DEX_PREOPT := false
LOCAL_MODULE_TAGS := optional
LOCAL_SRC_FILES := $(LOCAL_MODULE).apk
LOCAL_CERTIFICATE := platform
LOCAL_MODULE_CLASS := APPS
LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
LOCAL_MODULE_PATH := $(TARGET_OUT)/app
LOCAL_MULTILIB :=both
LOCAL_SHARED_LIBRARIES := $(foreach p,$(wildcard $(CPU_ARCH)/*.so),$(patsubst %.so,%,$(shell basename $(p))))
include $(BUILD_PREBUILT)
2、java编译依赖第三方jar包
framework.jar使用如下方式依赖第三方jar
LOCAL_JAVA_LIBRARIES += hitechmwinf
在代码中import包中的类，依然提示找不到，对比其他jar包的使用方式，还需要添加
framework_docs_LOCAL_API_CHECK_JAVA_LIBRARIES += \
hitechmwinf
3、编译不依赖framework.jar的jar包
当framework.jar编译时依赖jar包A.jar。如果A.jar编译中依赖了framework.java,编译framework.jar时会出现循环依赖的错误。
解决方法：在Android.mk中添加使用如下选项
LOCAL_JAVA_LIBRARIES := core-oj core-libart
LOCAL_NO_STANDARD_LIBRARIES := true
LOCAL_JARJAR_RULES := $(LOCAL_PATH)/jarjar-rules.txt
LOCAL_JARJAR_RULES把编译时引用的android包替换为非Android包，替换的包可以自行决定，例如
rule com.squareup.** com.android.@1
注意：如果使用的包是java1.7版本的，还需添加
LOCAL_JAVA_LANGUAGE_VERSION := 1.7
