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java – How can I add a 3rd-party library to an Android AOSP build?

Posted by: admin June 15, 2020 Leave a comment

Questions:

I am trying to add the Jackson JSON library to my AOSP project. I am able to compile my project and flash it to a phone, but I get a runtime error:

E/JavaBinder( 1689): java.lang.NoClassDefFoundError: Failed resolution of: Lcom/fasterxml/jackson/core/JsonFactory;
...
E/JavaBinder( 1689): Caused by: java.lang.ClassNotFoundException: Didn't find class "com.fasterxml.jackson.core.JsonFactory" on path: DexPathList[[zip file "/system/framework/guice.jar", zip file "/system/framework/beanshell.jar", zip file "/system/framework/services.jar", zip file "/system/framework/ethernet-service.jar", zip file "/system/framework/wifi-service.jar"],nativeLibraryDirectories=[/vendor/lib, /system/lib]]

I have tried including Jackson both from source, and jar. Here are my Android.mk files for each:


SOURCE Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_SRC_FILES := $(call all-java-files-under,.)
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE:= com.fasterxml.jackson.core
include $(BUILD_JAVA_LIBRARY)

# Copy XML to /system/etc/permissions/
include $(CLEAR_VARS)
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE := com.fasterxml.jackson.core.xml
LOCAL_MODULE_CLASS := ETC
LOCAL_MODULE_PATH := $(TARGET_OUT_ETC)/permissions
LOCAL_SRC_FILES := $(LOCAL_MODULE)
include $(BUILD_PREBUILT)

SOURCE com.fasterxml.jackson.core.xml (referenced above)

<?xml version="1.0" encoding="utf-8"?>
<permissions>
    <library name="com.fasterxml.jackson.core.xml"
        file="/system/framework/com.fasterxml.jackson.jar" />
</permissions>

JAR Android.mk

LOCAL_PATH := $(call my-dir)
include $(CLEAR_VARS)
LOCAL_MODULE := jackson
LOCAL_MODULE_TAGS := optional
LOCAL_SRC_FILES := jackson-core-2.5.0.jar
LOCAL_MODULE_CLASS := JAVA_LIBRARIES
LOCAL_MODULE_SUFFIX := $(COMMON_JAVA_PACKAGE_SUFFIX)
include $(BUILD_PREBUILT)

I have also added a jackson entry for in LOCAL_JAVA_LIBRARIES := section of the Android.mk file where I want to use Jackson (frameworks/base/services). No matter what I’ve tried, I get a ClassNotFoundException.

What am I missing? Have I done anything unnecessary?

How to&Answers:

To include a 3rd party library from source:

  1. copy the library’s source into a directory under $ANDROID_BUILD_TOP/external/ (ex: $ANDROID_BUILD_TOP/external/jackson)
  2. Create an Android.mk file, and place it in the library’s folder (ex: $ANDROID_BUILD_TOP/external/jackson/Android.mk

    Contents of Android.mk:

    # required (setup the build environment)
    LOCAL_PATH := $(call my-dir)
    include $(CLEAR_VARS)
    
    # optional step to automate some pre-compilation steps for this library
    # run `mvn generate-sources` before we compile
    $(info $(shell (mvn generate-sources -f $(LOCAL_PATH)/pom.xml)))
    
    # required (the name of the library we are building)
    LOCAL_MODULE := jackson
    
    # required (paths to all directories that include source code)
    # note the difference between the := (first line) and += (every other line)
    LOCAL_SRC_FILES := $(call all-java-files-under, src/main)
    LOCAL_SRC_FILES += $(call all-java-files-under, target/generated-sources)
    
    # required (tell the build system what kind of thing we are building)
    include $(BUILD_JAVA_LIBRARY)
    
  3. Add the library to the PRODUCT_BOOT_JARS section of your mk file. Which file you edit depends on what you are building (ex: build/target/product/core_minimal.mk)

    Original

    PRODUCT_BOOT_JARS := \
        okhttp \
        core-junit \
        bouncycastle \
        ext \
        gson
    

    Modified

    PRODUCT_BOOT_JARS := \
        okhttp \
        core-junit \
        bouncycastle \
        ext \
        gson \
        jackson
    
  4. For each submodule of your AOSP project (ex: frameworks/base), that you want to have access to the library, find the makefile (ex: $ANDROID_BUILD_TOP/frameworks/base/Android.mk and add an entry for your library to the LOCAL_JAVA_LIBRARIES line. Example:

    Original

    LOCAL_JAVA_LIBRARIES := guice gson
    

    Modified

    LOCAL_JAVA_LIBRARIES := guice gson jackson
    
  5. Compile your project.