android - Android系统从armeabi,armeabi-v7a,arm64-v8a加载原生库(so文件)有什么规律？

Question

假设我们在下面有一个 jni 文件夹结构。

armeabi
    a.so
    b.so
armeabi-v7a
    a.so

在基于ARMv7的设备上，我想加载b.so，但是“armeabi-v7a”文件夹下没有b.so，所以系统会报找不到库错误还是使用b.so在“armeabi”文件夹下？

更进一步，系统在armeabi,armeabi-v7a,arm64-v8a,中以什么顺序查找so文件>x86,x86_64?例如，在基于x86_64的设备上，系统首先在文件夹x86_64中寻找so文件，如果没有找到，系统会继续在x86中寻找文件,arm64-v8a,armeabi-v7a,armeabi 按顺序？

Answer 1

你见过吗:http://developer.android.com/ndk/guides/abis.html#am

我相信它可以回答您的问题:

Both the Play Store and Package Manager expect to find NDK-generated libraries on filepaths inside the APK matching the following pattern:

/lib/<abi>/lib<name>.so

If the system does not find the native shared libraries where it expects them, it cannot use them. In such a case, the app itself has to copy the libraries over, and then perform dlopen().

页面的下方是这个特殊的部分:

Automatic extraction of native code at install time

When installing an application, the package manager service scans the APK, and looks for any shared libraries of the form:

lib/<primary-abi>/lib<name>.so

If none is found, and you have defined a secondary ABI, the service scans for shared libraries of the form:

lib/<secondary-abi>/lib<name>.so

When it finds the libraries that it's looking for, the package manager copies them to /lib/lib.so, under the application's data directory (data/data//lib/). If there is no shared-object file at all, the application builds and installs, but crashes at runtime.

因此，如果您使用的是 armeabi-v7a 架构，则必须复制 lib/armeabi/libb.so 文件并使用 dlopen()，因为 PackageManager 什么都不知道需要在您的应用中加载但确实在 lib/armeabi-v7a 目录中找到的内容。