System.loadLibrary(...) 在我的情况下找不到本机库 [英] System.loadLibrary(...) couldn't find native library in my case

问题描述

我想使用来自另一个 Android 项目的现有本机库，因此我只是将 NDK 构建的库 (libcalculate.so) 复制到我的新 Android 项目中.在我的新 Android 项目中，我创建了一个文件夹 libs/armeabi/ 并将 libcalculate.so 放在那里.没有 jni/文件夹.我的测试设备采用 ARM 架构.

I want to use a existing native library from another Android project, so I just copied the NDK built library (libcalculate.so) to my new Android project. In my new Android project I created a folder libs/armeabi/ and put libcalculate.so there. There is no jni/ folder. My testing device has ARM architecture.

在我的 java 代码中，我通过以下方式加载库:

In my java code I load the library by:

  static{
    System.loadLibrary("calculate");
  }

当我运行我的新 android 项目时，出现错误:

When I run my new android project, I got error:

java.lang.UnsatisfiedLinkError:  ...
nativeLibraryDirectories=[/vendor/lib, /system/lib]]] couldn't find "libcalculate.so"

因此，正如错误所说，复制的本机库不在/verdor/lib 或/system/lib 中，在我的情况下如何解决此问题?

So, as error says, the copied native library is not in /verdor/lib or /system/lib , how to resolve this problem in my case?

(我解压了apk包，lib/下有libcalculate.so)

(I unziped the apk package, under lib/ there is libcalculate.so)

====更新======

我也尝试在项目根目录下创建一个jni/文件夹，在jni/下添加一个Android.mk文件.Android.mk 的内容是:

I also tried to create a jni/ folder under project root, and add an Android.mk file under jni/. The content of Android.mk is:

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)
LOCAL_MODULE    := libcalculate
LOCAL_SRC_FILES := libcalculate.so
include $(PREBUILT_SHARED_LIBRARY)

然后，在项目根目录下，我执行了 ndk-build .然后通过ndk-build生成armeabi/和armeabi-v7a/目录(文件夹内有libcalculate.so)

Then, under project root, I executed ndk-build . After that, the armeabi/ and armeabi-v7a/ directories are generated by ndk-build (with libcalculate.so inside the folder).

然后我运行我的maven构建项目成功.在最终的 apk 包中，有:

Then I run my maven build the project successfully. In the final apk package, there are:

lib/armeabi/libcalculate.so
lib/armeabi-v7a/libcalculate.so

但是当我运行我的应用程序时，抛出同样的错误:

But when I run my app, the same error throw:

java.lang.UnsatisfiedLinkError:  ...
nativeLibraryDirectories=[/vendor/lib, /system/lib]]] couldn't find "libcalculate.so"

推荐答案

为了根本原因(也许同时解决您的问题)，您可以这样做:

To root cause (and maybe solve your issue in the same time), here is what you can do:

1. 删除 jni 文件夹和所有 .mk 文件.如果您不编译任何内容，则不需要这些或 NDK.

1. Remove the jni folder and all the .mk files. You don't need these nor the NDK if you aren't compiling anything.

将您的 libcalculate.so 文件复制到 /libs/(armeabi|armeabi-v7a|x86|...) 中.使用 Android Studio 时，它是 /app/src/main/jniLibs/(armeabi|armeabi-v7a|x86|...)，但我看到您正在使用 eclipse.

Copy your libcalculate.so file inside <project>/libs/(armeabi|armeabi-v7a|x86|...) . When using Android Studio, it's <project>/app/src/main/jniLibs/(armeabi|armeabi-v7a|x86|...), but I see you're using eclipse.

构建您的 APK 并将其作为 zip 文件打开，以检查您的 libcalculate.so 文件是否在 lib/(armeabi|armeabi-v7a|x86|...).

Build your APK and open it as a zip file, to check that your libcalculate.so file is inside lib/(armeabi|armeabi-v7a|x86|...).

删除并安装您的应用程序

Remove and install your application

运行dumpsys 包包|grep yourpackagename 以获取应用程序的 nativeLibraryPath 或 legacyNativeLibraryDir.

Run dumpsys package packages | grep yourpackagename to get the nativeLibraryPath or legacyNativeLibraryDir of your application.

在您拥有的 nativeLibraryPath 或 legacyNativeLibraryDir/armeabi 上运行 ls，以检查您的 libcalculate.so 是否确实存在.

Run ls on the nativeLibraryPath you had or on legacyNativeLibraryDir/armeabi, to check if your libcalculate.so is indeed there.

如果它在那里，请检查它是否没有从您的原始 libcalculate.so 文件中更改:它是否针对正确的体系结构编译，是否包含预期的符号，是否存在任何缺少的依赖项.您可以使用 readelf 分析 libcalculate.so.

If it's there, check if it hasn't been altered from your original libcalculate.so file: is it compiled against the right architecture, does it contain the expected symbols, are there any missing dependencies. You can analyze libcalculate.so using readelf.

为了检查第 5-7 步，您可以使用我的应用程序代替命令行和 readelf:本机库监视器

In order to check step 5-7, you can use my application instead of command lines and readelf: Native Libs Monitor

PS:很容易混淆默认情况下应该放置或生成 .so 文件的位置，这里是一个摘要:

PS: It's easy to get confused on where .so files should be put or generated by default, here is a summary:

• libs/CPU_ABI 在 Eclipse 项目中

• libs/CPU_ABI inside an eclipse project

jniLibs/CPU_ABI 在 Android Studio 项目中

jniLibs/CPU_ABI inside an Android Studio project

jni/CPU_ABI 在 AAR 中

lib/CPU_ABI 在最终 APK 中

在 <5.0 设备上应用的 nativeLibraryPath 内部，以及在 >=5.0 设备上应用的 legacyNativeLibraryDir/CPU_ARCH 内部.

inside the app's nativeLibraryPath on a <5.0 device, and inside the app's legacyNativeLibraryDir/CPU_ARCH on a >=5.0 device.

其中 CPU_ABI 是以下任一项:armeabi、armeabi-v7a、arm64-v8a、x86、x86_64、mips、mips64.取决于您的目标架构和您的库已经编译.

Where CPU_ABI is any of: armeabi, armeabi-v7a, arm64-v8a, x86, x86_64, mips, mips64. Depending on which architectures you're targeting and your libs have been compiled for.

另请注意，CPU_ABI 目录之间不会混合库:您需要使用的完整集合，armeabi 文件夹内的库不会安装在 armeabi-v7a 设备，如果 APK 中的 armeabi-v7a 文件夹中有任何库.

Note also that libs aren't mixed between CPU_ABI directories: you need the full set of what you're using, a lib that is inside the armeabi folder will not be installed on a armeabi-v7a device if there are any libs inside the armeabi-v7a folder from the APK.

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