动态库so打包到android apk

最新推荐文章于 2021-05-26 23:50:46 发布

原创最新推荐文章于 2021-05-26 23:50:46 发布 · 2.9k 阅读

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#android #jni #library #makefile #module #build

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本文介绍了如何将动态库libjnisimple.so编译并打包到Android APK中。在编译过程中，强调了JNI_OnLoad函数需用C编译器编译，并在Java中定义为native。如果未找到JNI_OnLoad，dalvik会跳过初始化。最后，通过Android.mk文件编译APK，并使用adb进行安装和卸载操作。

编译libjnisimple.so

Android/development/samples/SimpleJNI/jni/Android.mk

# This makefile supplies the rules for building a library of JNI code for
# use by our example of how to bundle a shared library with an APK.

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

LOCAL_MODULE_TAGS := samples

# This is the target being built.
LOCAL_MODULE:= libsimplejni


# All of the source files that we will compile.
LOCAL_SRC_FILES:= \
  native.cpp

# All of the shared libraries we link against.
LOCAL_SHARED_LIBRARIES := \
        libutils

# No static libraries.
LOCAL_STATIC_LIBRARIES :=

# Also need the JNI headers.
LOCAL_C_INCLUDES += \
        $(JNI_H_INCLUDE)

# No special compiler flags.
LOCAL_CFLAGS +=

# Don't prelink this library.  For more efficient code, you may want
# to add this library to the prelink map and set this to true. However,
# it's difficult to do this for applications that are not supplied as
# part of a system image.

LOCAL_PRELINK_MODULE := false

include $(BUILD_SHARED_LIBRARY)

注意:在jni的C++代码中，JNI_OnLoad要用C编译器编译（extern "C"），否则会出现dalvik找不到JNI_OnLoad函数并跳过初始化。

D/dalvikvm( 4581): No JNI_OnLoad found in /data/data/xxxxlib/libsimplejni.so 0x481f3b78, skipping init

编译apk
Android/development/samples/SimpleJNI/Android.mk

# This makefile shows how to build a shared library and an activity that
# bundles the shared library and calls it using JNI.

TOP_LOCAL_PATH:= $(call my-dir)

# Build activity

LOCAL_PATH:= $(TOP_LOCAL_PATH)
include $(CLEAR_VARS)

LOCAL_MODULE_TAGS := samples

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

LOCAL_PACKAGE_NAME := SimpleJNI

LOCAL_JNI_SHARED_LIBRARIES := libsimplejni

LOCAL_PROGUARD_ENABLED := disabled

include $(BUILD_PACKAGE)

# ============================================================

# Also build all of the sub-targets under this one: the shared library.
include $(call all-makefiles-under,$(LOCAL_PATH))

注意：jni中实现的function，在java中必须要定义成native

编辑jni层文件编译so & apk

adb shell pm uninstall -f com.example.android.simplejni

adb install SimpleJNI.apk