Android: Creating custom SDK

Android framework SDK that is published by Google is used by app developers to link to Android framework when they develop Android apps. What if your company needs to add new APIs to the framework? It is not recommended to add this into Android framework SDK and publish customized framework SDK. The ideal method in this case is to publish your custom SDK that contains only the new APIs that is specific to your platform.

Google has already given a template to do this under device/sample. That is a good place to start to make your custom SDK.

Copy device/sample to device/mycompany
Remove unwanted directories like 'overlays', 'etc', 'skins'.

Final directory structure will be as follows:

device
  mycompany
     apps
     frameworks
     |  MycompanyLibrary
     |  |  java
     |  |  |  com
     |  |  |     mycompany
     |  |  |        android
     |  |  |           sdk
     |  |  |              Myfeature.java
     |  |  Android.mk
     |  |  AndroidManifest.xml
     |  |  com.mycompany.android.sdk.xml
     |  |  README.txt
     |  Android.mk
     products
     |  addon_stub_defs
     |  AndroidProducts.mk
     |  mycompany_addon.mk
     |  source.properties
     sdk_addon
     |  hardware.ini
     |  manifest.ini
     Android.mk
     CleanSpec.mk
     README.txt

Implementation for the SDK apis goes under 'device/mycompany/frameworks' directory.

frameworks/MycompanyLibrary/java/com/mycompany/android/sdk
Namespace can be adjusted as per your conventions. In this example namespace is 'java.com.mycompany.sdk'.

Implement your SDK feature in Myfeature.java. If required use JNI to if your implementation requires lower layers.

The list below shows all the changes that are needed in the files that are copied from 'device/sample'.

frameworks/MycompanyLibrary/Android.mk

# Copyright (C) 2008 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

ifneq ($(TARGET_BUILD_JAVA_SUPPORT_LEVEL),)

# This makefile shows how to build your own shared library that can be
# shipped on the system of a phone, and included additional examples of
# including JNI code with the library and writing client applications against it.

LOCAL_PATH := $(call my-dir)

# The jar library
# ============================================================
include $(CLEAR_VARS)

LOCAL_SRC_FILES := $(call all-subdir-java-files)

LOCAL_MODULE_TAGS := optional

# This is the target being built.
LOCAL_MODULE:= com.mycompany.android.sdk

include $(BUILD_JAVA_LIBRARY)

# The aar library. To be manually made at Android root dir with
#  make out/target/common/obj/JAVA_LIBRARIES/com.mycompany.android.aar.sdk_intermediates/javalib.aar
# ============================================================
include $(CLEAR_VARS)

LOCAL_SRC_FILES := $(call all-subdir-java-files)
LOCAL_RESOURCE_DIR := $(LOCAL_PATH)/res
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE:= com.mycompany.android.aar.sdk

include $(BUILD_STATIC_JAVA_LIBRARY)

# the documentation
# ============================================================
include $(CLEAR_VARS)

LOCAL_SRC_FILES := $(call all-subdir-java-files) $(call all-subdir-html-files)

LOCAL_MODULE:= mycompany_sdk_v1.0.0
LOCAL_DROIDDOC_OPTIONS :=
LOCAL_MODULE_CLASS := JAVA_LIBRARIES
LOCAL_DROIDDOC_USE_STANDARD_DOCLET := true

include $(BUILD_DROIDDOC)

# The JNI component
# ============================================================
# Also build all of the sub-targets under this one: the library's
# associated JNI code, and a sample client of the library.
include $(CLEAR_VARS)

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

endif # JAVA_SUPPORT

frameworks/MycompanyLibrary/AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:androidprv="http://schemas.android.com/apk/prv/res/android"
   package="com.mycompany.android.aar.sdk" >
</manifest>

frameworks/MycompanyLibrary/com.mycompany.android.sdk.xml

<?xml version="1.0" encoding="utf-8"?>
<permissions>
    <library name="com.mycompany.android.sdk"
            file="/system/framework/com.mycompany.android.sdk.jar"/>
</permissions>

products/addon_stub_defs

+com.mycompany.android.sdk.*

products/AndroidProducts.mk

# This file should set PRODUCT_MAKEFILES to a list of product makefiles
# to expose to the build system.  LOCAL_DIR will already be set to
# the directory containing this file.
#
# This file may not rely on the value of any variable other than
# LOCAL_DIR; do not use any conditionals, and do not look up the
# value of any variable that isn't set in this file or in a file that
# it includes.
#

PRODUCT_MAKEFILES := \
  $(LOCAL_DIR)/mycompany_addon.mk

products/mycompany_addon.mk

DEVICE_PACKAGE_OVERLAYS := device/qcom/msm8996_gvmq/overlay

#BOARD_COMMON_DIR := device/qcom/common
#BOARD_OPENSOURCE_DIR := device/qcom/msm8909w/opensource
BOARD_DLKM_DIR := device/qcom/common/dlkm
#DEVICE_COMMON_PATH := $(BOARD_COMMON_DIR)

-include device/qcom/common/utils.mk

#$(call inherit-product, $(BOARD_COMMON_DIR)/common.mk)

# List of apps and optional libraries (Java and native) to put in the add-on system image.
PRODUCT_PACKAGES := \
    MycompanyLibraryClient \
 com.mycompany.android.sdk

# Manually copy the optional library XML files in the system image.
PRODUCT_COPY_FILES := \
    device/mycompany/frameworks/MycompanyLibrary/com.mycompany.android.sdk.xml: \
    system/etc/permissions/com.mycompany.android.sdk.xml

# name of the add-on
PRODUCT_SDK_ADDON_NAME := mycompany_sdk_v1.0.0

PRODUCT_SDK_ADDON_SYS_IMG_SOURCE_PROP := $(LOCAL_PATH)/source.properties

# Copy the manifest and hardware files for the SDK add-on.
# The content of those files is manually created for now.
PRODUCT_SDK_ADDON_COPY_FILES := \
    device/mycompany/sdk_addon/manifest.ini:manifest.ini \
    device/mycompany/sdk_addon/hardware.ini:hardware.ini


# Add this to PRODUCT_SDK_ADDON_COPY_FILES to copy the files for an
# emulator skin (or for samples)
#$(call find-copy-subdir-files,*,device/sample/skins/WVGAMedDpi,skins/WVGAMedDpi)

# Copy the jar files for the optional libraries that are exposed as APIs.
PRODUCT_SDK_ADDON_COPY_MODULES := \
    com.mycompany.android.sdk:libs/mycompany_sdk_v1.0.0.jar

# Rules for public APIs
PRODUCT_SDK_ADDON_STUB_DEFS := $(LOCAL_PATH)/addon_stub_defs

# Name of the doc to generate and put in the add-on. This must match the name defined
# in the optional library with the tag
#    LOCAL_MODULE:= platform_library
# in the documentation section.
PRODUCT_SDK_ADDON_DOC_MODULES := mycompany_sdk_v1.0.0

# This add-on extends the default sdk product.

$(call inherit-product, $(SRC_TARGET_DIR)/product/sdk.mk)

# Real name of the add-on. This is the name used to build the add-on.
# Use 'make PRODUCT-<PRODUCT_NAME>-sdk_addon' to build the add-on.
PRODUCT_NAME := mycompany_addon

products/source.properties

Addon.NameId=mycompany_sdk_v1.0.0
Pkg.Desc=Provides the Mycompany APIs to 3rd party apk developer
Addon.VendorId=mycompany
Archive.Arch=ANY
Addon.NameDisplay=MycompanySDK
Addon.VendorDisplay=Mycompany
Archive.Os=ANY
Pkg.Revision=1
AndroidVersion.ApiLevel=19

sdk_addon/manifest.ini

# SDK Add-on Manifest
# File encoding is UTF-8

# Name and vendor of the add-on.
# Add-ons are uniquely identified by a string composed of name, vendor and api.
# 2 add-ons with the same identifier cannot be installed in the same SDK
# and only the add-on with the highest rev number will be installed.
# Name and vendor are used to create folder names, so they shouldn't contain
# any special characters. Also, the character ':' is forbidden.
# Mandatory character set: a-z A-Z 0-9 _.-
name=Mycompany Add-On
vendor=Mycompany
description=mycompany add-on

# version of the Android platform on which this add-on is built.
api=15

# revision of the add-on. This must be a strict integer.
revision=1

# list of libraries, separated by a semi-colon.
# This must be the name of the libraries, as required by the
# <uses-library> node in the AndroidManifest.xml file.
libraries=com.mycompany.android.sdk

# details for each library. format is:
# <library.name>=<name>.jar;<desc>
# where
# <library.name>: the name of the library defined in the property "libraries" above.
# <name>.jar: the jar file containing the library API. This is to be located in
#             the add-on folder in libs/
com.mycompany.android.sdk=mycompany_sdk_v1.0.0.jar;Mycompany SDK

# default skin name. Optional. Only useful if the add-on has its own skin, or
# if it wishes to override the default skin of the base platform.
# This should be the name of the skin in the skins/ folder of the add-on.
#skin=WVGAMedDpi

# USB Vendor ID
# This 16-bit integer allows adb to detect new devices, by extending the list
# of USB Vendor IDs it knows. After installing an add-on the command
# 'android update' adb' must be run to update a file that adb reads during
# start-up.
#usb-vendor=0x0000

README.txt

To make the sdk run

make -j8 PRODUCT-mycompany_addon-sdk_addon

Use the command in README to build the SDK. It will generate mycompany_sdk_v1.0.0.jar that can be used in applications.
It will also generate the sdk libraries to be used on target - 'com.mycompany.android.sdk.xxx' files.