在Android5.0系统上加载位于SD卡上的本地动态库

• 最近在加载位于Android设备SDCARD上的本地动态库时遇到权限问题,估计是5.0系统权限管理限制更多,而SDCARD上文件基本上没有可执行权限,而一般非root用户无法通过chmod为其添加.

  1. 加载代码(APP启动时):

     System.load("/mnt/sdcard/libfeatureA.so");

  2. 异常闪退:

     dlopen("/mnt/sdcard/libfeatureA.so", RTLD_LAZY) failed: dlopen failed: couldn't map "/mnt/sdcard/libfeatureA.so" segment 2: Operation not permitted

• 加载位于SD卡的so权限不够,那么将so复制到APP内部数据空间再加载呢,经测试是可行的.

  1. 加载代码(APP启动时):

     NativeLibraryLoader.loadLibrary(this, "/mnt/sdcard", "libfeatureA.so");NativeLibraryLoader.loadLibrary(this, "/mnt/sdcard", "libfeatureB.so");

  2. 库加载类NativeLibraryLoader实现

     /** * Created by [e-mail] on 2015/10/10. */public class NativeLibraryLoader {    public static boolean loadLibrary(Context context, String libPath, String libName) {        File libs_dir = context.getDir("libs", Context.MODE_PRIVATE);        String new_file_name = libs_dir.getPath() + "/" + libName;        String old_file_name = libPath + "/" + libName;        if (!copyLibrary(new_file_name, old_file_name)) {            return false;        }        try {            System.load(new_file_name);        } catch (Exception ex) {            ex.printStackTrace();            return false;        }        return true;    }    private static boolean copyLibrary(String new_file_name, String old_file_name) {        FileInputStream fis = null;        FileOutputStream fos = null;        try {            File new_file = new File(new_file_name);            File old_file = new File(old_file_name);            /* delete old library if exists. */            if (new_file.exists()) new_file.delete();            fis = new FileInputStream(old_file);            fos = new FileOutputStream(new_file);            int     dataSize;            byte[]  dataBuffer = new byte[2048];            while ((dataSize = fis.read(dataBuffer)) != -1) {                fos.write(dataBuffer, 0, dataSize);            }            fos.flush();            return true;        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                if (fos != null) fos.close();            } catch (Exception e) {                e.printStackTrace();            }            try {                if (fis != null) fis.close();            } catch (Exception e) {                e.printStackTrace();            }        }        return false;    }}