最近專案需要接入音視訊SDK,功能還沒開發,打出來的apk大了30多M…

曲線救國.

依賴的so都是音視訊的必要的核心SDK,不能刪除,但是又不想上傳一個超級大的apk到市場,

那麼解決的方案就是浪費使用者流量,畢竟現在網速那麼快,流量也幾乎等於不要錢了…

這叫從技術角度偽減小apk,其實在用到的時候還是要下載這些apk,但是上傳到市場小了就行.

so檔案不打包進apk,在安裝完應用開啟app的時候通過後臺下載so庫，將下載下來的so檔案再寫入到app裡面。
Android載入so檔案的方式有兩種：

System.loadLibrary();
System.load();

它們都可以用來裝載庫檔案,但是System.load引數必須為庫檔案的絕對路徑，可以是任意路徑；System.loadLibrary引數為庫檔名，不包含庫檔案的副檔名，必須是在JVM屬性java.library.path所指向的路徑中，路徑可以通過System.getProperty(‘java.library.path’) 獲得。所有動態載入的時候我們不能用System.loadLibrary，只能用System.load來載入。

我們知道,如果不做任何修改的話,我們靜態載入的so,他的路徑是App應用的system.lib路徑

由於我們是要動態下載so,並且要把下載的so 拷貝到一個目標路徑,去載入

最理想的方案就是直接指定packagename/system/lib,

既然是最理想的,那麼這方案肯定是不行的,因為這個目錄,只有讀的許可權,沒有寫的許可權.

拿root的 手機可以測試,我們手動把so.拷貝到這個目錄是可以的.

那麼我們只能在系統載入so的路徑中,額外新增一個系統認可的載入路徑即可,

最終的結果如下圖:我們把我們自定義的路徑加入到系統能認識的dexPathList裡面

 Field pathListField = ShareReflectUtil.findField(classLoader, "pathList");
            Object dexPathList = pathListField.get(classLoader);

            Field nativeLibraryDirectories = ShareReflectUtil.findField(dexPathList, "nativeLibraryDirectories");

            List<File> libDirs = (List<File>) nativeLibraryDirectories.get(dexPathList);
            libDirs.add(0, folder);
            Field systemNativeLibraryDirectories =
            // 就是這個路徑,把我們下載的路徑新增到這裡
                    ShareReflectUtil.findField(dexPathList, "systemNativeLibraryDirectories");
            List<File> systemLibDirs = (List<File>) systemNativeLibraryDirectories.get(dexPathList);
            Method makePathElements =
                    ShareReflectUtil.findMethod(dexPathList, "makePathElements", List.class);
            libDirs.addAll(systemLibDirs);
            Object[] elements = (Object[]) makePathElements.
                    invoke(dexPathList, libDirs);
            Field nativeLibraryPathElements = ShareReflectUtil.findField(dexPathList, "nativeLibraryPathElements");
            nativeLibraryPathElements.setAccessible(true);
            nativeLibraryPathElements.set(dexPathList, elements);
 

這裡我以接入某度的地圖SDK為例,首先我們在gradle 中排除某度的so.就是打包apk的時候不打進去

 packagingOptions {
  	    exclude 'lib/armeabi/libindoor.so'
        exclude 'lib/armeabi/libBaiduMapSDK_base_v5_2_0.so'
        exclude 'lib/armeabi/liblocSDK7b.so'
}
        

在application中呼叫動態載入so的方法,這裡不提供下載方法,我們直接copy ,so檔案到sd卡目錄

 private void dynamicSo() {
        String dir = FileUtils.getAppRecordDir(sApplication).toString();
        SoFile.loadSoFile(sApplication, dir);
    }

 

關鍵的來了.我們這邊用借用下騰訊tinker的動態載入部分程式碼

public class TinkerLoadLibrary {
    private static final String TAG = "Tinker.LoadLibrary";

    public static synchronized void installNativeLibraryPath(ClassLoader classLoader, File folder)
            throws Throwable {
        if (folder == null || !folder.exists()) {
            Logger.e(TAG, "installNativeLibraryPath, folder %s is illegal", folder);
            return;
        }
        // android o sdk_int 26
        // for android o preview sdk_int 25
        if ((Build.VERSION.SDK_INT == 25 && getPreviousSdkInt() != 0)
                || Build.VERSION.SDK_INT > 25) {
            try {
                V25.install(classLoader, folder);
                return;
            } catch (Throwable throwable) {
                // install fail, try to treat it as v23
                // some preview N version may go here
                Logger.e(TAG, "installNativeLibraryPath, v25 fail, sdk: %d, error: %s, try to fallback to V23",
                        Build.VERSION.SDK_INT, throwable.getMessage());
                V23.install(classLoader, folder);
            }
        } else if (Build.VERSION.SDK_INT >= 23) {
            try {
                V23.install(classLoader, folder);
            } catch (Throwable throwable) {
                // install fail, try to treat it as v14
                Logger.e(TAG, "installNativeLibraryPath, v23 fail, sdk: %d, error: %s, try to fallback to V14",
                        Build.VERSION.SDK_INT, throwable.getMessage());

                V14.install(classLoader, folder);
            }
        } else if (Build.VERSION.SDK_INT >= 14) {
            V14.install(classLoader, folder);
        }
    }

    /**
     * fuck部分機型刪了該成員屬性，相容
     *
     * @return 被廠家刪了返回1，否則正常讀取
     */
    @TargetApi(Build.VERSION_CODES.M)
    private static int getPreviousSdkInt() {
        try {
            return Build.VERSION.PREVIEW_SDK_INT;
        } catch (Throwable ignore) {
        }
        return 1;
    }

    private static final class V14 {
        private static void install(ClassLoader classLoader, File folder) throws Throwable {
            Field pathListField = ShareReflectUtil.findField(classLoader, "pathList");
            Object dexPathList = pathListField.get(classLoader);

            ShareReflectUtil.expandFieldArray(dexPathList, "nativeLibraryDirectories", new File[]{folder});
        }
    }

    private static final class V23 {
        private static void install(ClassLoader classLoader, File folder) throws Throwable {
            Field pathListField = ShareReflectUtil.findField(classLoader, "pathList");
            Object dexPathList = pathListField.get(classLoader);

            Field nativeLibraryDirectories = ShareReflectUtil.findField(dexPathList, "nativeLibraryDirectories");

            List<File> libDirs = (List<File>) nativeLibraryDirectories.get(dexPathList);
            libDirs.add(0, folder);
            Field systemNativeLibraryDirectories =
                    ShareReflectUtil.findField(dexPathList, "systemNativeLibraryDirectories");
            List<File> systemLibDirs = (List<File>) systemNativeLibraryDirectories.get(dexPathList);
            Method makePathElements =
                    ShareReflectUtil.findMethod(dexPathList, "makePathElements", List.class, File.class, List.class);
            ArrayList<IOException> suppressedExceptions = new ArrayList<>();
            libDirs.addAll(systemLibDirs);
            Object[] elements = (Object[]) makePathElements.
                    invoke(dexPathList, libDirs, null, suppressedExceptions);
            Field nativeLibraryPathElements = ShareReflectUtil.findField(dexPathList, "nativeLibraryPathElements");
            nativeLibraryPathElements.setAccessible(true);
            nativeLibraryPathElements.set(dexPathList, elements);
        }
    }

    private static final class V25 {
        private static void install(ClassLoader classLoader, File folder) throws Throwable {
            Field pathListField = ShareReflectUtil.findField(classLoader, "pathList");
            Object dexPathList = pathListField.get(classLoader);

            Field nativeLibraryDirectories = ShareReflectUtil.findField(dexPathList, "nativeLibraryDirectories");

            List<File> libDirs = (List<File>) nativeLibraryDirectories.get(dexPathList);
            libDirs.add(0, folder);
            Field systemNativeLibraryDirectories =
                    ShareReflectUtil.findField(dexPathList, "systemNativeLibraryDirectories");
            List<File> systemLibDirs = (List<File>) systemNativeLibraryDirectories.get(dexPathList);
            Method makePathElements =
                    ShareReflectUtil.findMethod(dexPathList, "makePathElements", List.class);
            libDirs.addAll(systemLibDirs);
            Object[] elements = (Object[]) makePathElements.
                    invoke(dexPathList, libDirs);
            Field nativeLibraryPathElements = ShareReflectUtil.findField(dexPathList, "nativeLibraryPathElements");
            nativeLibraryPathElements.setAccessible(true);
            nativeLibraryPathElements.set(dexPathList, elements);
        }
    }
}

// 獲取路徑的類
public class ShareReflectUtil {

    /**
     * Locates a given field anywhere in the class inheritance hierarchy.
     *
     * @param instance an object to search the field into.
     * @param name     field name
     * @return a field object
     * @throws NoSuchFieldException if the field cannot be located
     */
    public static Field findField(Object instance, String name) throws NoSuchFieldException {
        for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Field field = clazz.getDeclaredField(name);

                if (!field.isAccessible()) {
                    field.setAccessible(true);
                }

                return field;
            } catch (NoSuchFieldException e) {
                // ignore and search next
            }
        }

        throw new NoSuchFieldException("Field " + name + " not found in " + instance.getClass());
    }

    public static Field findField(Class<?> originClazz, String name) throws NoSuchFieldException {
        for (Class<?> clazz = originClazz; clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Field field = clazz.getDeclaredField(name);

                if (!field.isAccessible()) {
                    field.setAccessible(true);
                }

                return field;
            } catch (NoSuchFieldException e) {
                // ignore and search next
            }
        }

        throw new NoSuchFieldException("Field " + name + " not found in " + originClazz);
    }

    /**
     * Locates a given method anywhere in the class inheritance hierarchy.
     *
     * @param instance       an object to search the method into.
     * @param name           method name
     * @param parameterTypes method parameter types
     * @return a method object
     * @throws NoSuchMethodException if the method cannot be located
     */
    public static Method findMethod(Object instance, String name, Class<?>... parameterTypes)
            throws NoSuchMethodException {
        for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Method method = clazz.getDeclaredMethod(name, parameterTypes);

                if (!method.isAccessible()) {
                    method.setAccessible(true);
                }

                return method;
            } catch (NoSuchMethodException e) {
                // ignore and search next
            }
        }

        throw new NoSuchMethodException("Method "
                + name
                + " with parameters "
                + Arrays.asList(parameterTypes)
                + " not found in " + instance.getClass());
    }

    /**
     * Locates a given method anywhere in the class inheritance hierarchy.
     *
     * @param clazz          a class to search the method into.
     * @param name           method name
     * @param parameterTypes method parameter types
     * @return a method object
     * @throws NoSuchMethodException if the method cannot be located
     */
    public static Method findMethod(Class<?> clazz, String name, Class<?>... parameterTypes)
            throws NoSuchMethodException {
        for (; clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Method method = clazz.getDeclaredMethod(name, parameterTypes);

                if (!method.isAccessible()) {
                    method.setAccessible(true);
                }

                return method;
            } catch (NoSuchMethodException e) {
                // ignore and search next
            }
        }

        throw new NoSuchMethodException("Method "
                + name
                + " with parameters "
                + Arrays.asList(parameterTypes)
                + " not found in " + clazz);
    }

    /**
     * Locates a given constructor anywhere in the class inheritance hierarchy.
     *
     * @param instance       an object to search the constructor into.
     * @param parameterTypes constructor parameter types
     * @return a constructor object
     * @throws NoSuchMethodException if the constructor cannot be located
     */
    public static Constructor<?> findConstructor(Object instance, Class<?>... parameterTypes)
            throws NoSuchMethodException {
        for (Class<?> clazz = instance.getClass(); clazz != null; clazz = clazz.getSuperclass()) {
            try {
                Constructor<?> ctor = clazz.getDeclaredConstructor(parameterTypes);

                if (!ctor.isAccessible()) {
                    ctor.setAccessible(true);
                }

                return ctor;
            } catch (NoSuchMethodException e) {
                // ignore and search next
            }
        }

        throw new NoSuchMethodException("Constructor"
                + " with parameters "
                + Arrays.asList(parameterTypes)
                + " not found in " + instance.getClass());
    }

    /**
     * Replace the value of a field containing a non null array, by a new array containing the
     * elements of the original array plus the elements of extraElements.
     *
     * @param instance      the instance whose field is to be modified.
     * @param fieldName     the field to modify.
     * @param extraElements elements to append at the end of the array.
     */
    public static void expandFieldArray(Object instance, String fieldName, Object[] extraElements)
            throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
        Field jlrField = findField(instance, fieldName);

        Object[] original = (Object[]) jlrField.get(instance);
        Object[] combined = (Object[]) Array.newInstance(original.getClass().getComponentType(), original.length + extraElements.length);

        // NOTE: changed to copy extraElements first, for patch load first

        System.arraycopy(extraElements, 0, combined, 0, extraElements.length);
        System.arraycopy(original, 0, combined, extraElements.length, original.length);

        jlrField.set(instance, combined);
    }

    /**
     * Replace the value of a field containing a non null array, by a new array containing the
     * elements of the original array plus the elements of extraElements.
     *
     * @param instance      the instance whose field is to be modified.
     * @param fieldName     the field to modify.
     */
    public static void reduceFieldArray(Object instance, String fieldName, int reduceSize)
            throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException {
        if (reduceSize <= 0) {
            return;
        }

        Field jlrField = findField(instance, fieldName);

        Object[] original = (Object[]) jlrField.get(instance);
        int finalLength = original.length - reduceSize;

        if (finalLength <= 0) {
            return;
        }

        Object[] combined = (Object[]) Array.newInstance(original.getClass().getComponentType(), finalLength);

        System.arraycopy(original, reduceSize, combined, 0, finalLength);

        jlrField.set(instance, combined);
    }

    public static Object getActivityThread(Context context,
                                           Class<?> activityThread) {
        try {
            if (activityThread == null) {
                activityThread = Class.forName("android.app.ActivityThread");
            }
            Method m = activityThread.getMethod("currentActivityThread");
            m.setAccessible(true);
            Object currentActivityThread = m.invoke(null);
            if (currentActivityThread == null && context != null) {
                // In older versions of Android (prior to frameworks/base 66a017b63461a22842)
                // the currentActivityThread was built on thread locals, so we'll need to try
                // even harder
                Field mLoadedApk = context.getClass().getField("mLoadedApk");
                mLoadedApk.setAccessible(true);
                Object apk = mLoadedApk.get(context);
                Field mActivityThreadField = apk.getClass().getDeclaredField("mActivityThread");
                mActivityThreadField.setAccessible(true);
                currentActivityThread = mActivityThreadField.get(apk);
            }
            return currentActivityThread;
        } catch (Throwable ignore) {
            return null;
        }
    }

    /**
     * Handy method for fetching hidden integer constant value in system classes.
     *
     * @param clazz
     * @param fieldName
     * @return
     */
    public static int getValueOfStaticIntField(Class<?> clazz, String fieldName, int defVal) {
        try {
            final Field field = findField(clazz, fieldName);
            return field.getInt(null);
        } catch (Throwable thr) {
            return defVal;
        }
    }
}

/**
 * 檔案描述:提供一個檔案讀寫和載入指定路徑下so的類
 *
 * @author :feilong on 2018/11/6
 */
public class SoFile {

    /**
     * 載入 so 檔案(直接指定你so下載的路徑即可)
     *
     * @param context
     * @param fromPath 下載到得sdcard目錄
     */
    public static void loadSoFile(Context context, String fromPath) {
        File dir = context.getDir("libs", Context.MODE_PRIVATE);
        if (!isLoadSoFile(dir)) {
            copy(fromPath, dir.getAbsolutePath());
        }

        try {
            TinkerLoadLibrary.installNativeLibraryPath(VchatApplication.getMyApplication().getBaseContext().getClassLoader(), dir);

        } catch (Throwable throwable) {
            Logger.e(throwable.getMessage());
        }
    }

    /**
     * 判斷 so 檔案是否存在
     *
     * @param dir
     * @return
     */
    public static boolean isLoadSoFile(File dir) {
        File[] currentFiles;
        currentFiles = dir.listFiles();
        boolean hasSoLib = false;
        if (currentFiles == null) {
            return false;
        }
        for (int i = 0; i < currentFiles.length; i++) {
            if (currentFiles[i].getName().contains("libwedsa23")) {
                hasSoLib = true;
            }
        }
        return hasSoLib;
    }

    /**
     * @param fromFile 指定的下載目錄
     * @param toFile   應用的包路徑
     * @return
     */
    public static int copy(String fromFile, String toFile) {
        //要複製的檔案目錄
        File root = new File(fromFile);
        //如同判斷SD卡是否存在或者檔案是否存在,如果不存在則 return出去
        if (!root.exists()) {
            return -1;
        }
        //如果存在則獲取當前目錄下的全部檔案 填充陣列
        File[] currentFiles = root.listFiles();

        //目標目錄
        File targetDir = new File(toFile);
        //建立目錄
        if (!targetDir.exists()) {
            targetDir.mkdirs();
        }
        if (currentFiles != null && currentFiles.length > 0) {
            //遍歷要複製該目錄下的全部檔案
            for (File currentFile : currentFiles) {
                if (currentFile.isDirectory()) {
                    //如果當前項為子目錄 進行遞迴
                    copy(currentFile.getPath() + "/", toFile + currentFile.getName() + "/");
                } else {
                    //如果當前項為檔案則進行檔案拷貝
                    if (currentFile.getName().contains(".so")) {
                        int id = copySdcardFile(currentFile.getPath(), toFile + File.separator + currentFile.getName());
                    }
                }
            }
        }
        return 0;
    }


    //檔案拷貝
    //要複製的目錄下的所有非子目錄(資料夾)檔案拷貝
    public static int copySdcardFile(String fromFile, String toFile) {
        try {
            FileInputStream fosfrom = new FileInputStream(fromFile);
            FileOutputStream fosto = new FileOutputStream(toFile);
            ByteArrayOutputStream baos = new ByteArrayOutputStream();
            byte[] buffer = new byte[1024];
            int len = -1;
            while ((len = fosfrom.read(buffer)) != -1) {
                baos.write(buffer, 0, len);
            }
            // 從記憶體到寫入到具體檔案
            fosto.write(baos.toByteArray());
            // 關閉檔案流
            baos.close();
            fosto.close();
            fosfrom.close();
            return 0;
        } catch (Exception ex) {
            return -1;
        }
    }

}

由於功力有限,原始碼以及底層的東西也不懂,都是谷歌的資料,和一步步除錯,之前也搜尋了很多之類的動態載入,但是都沒人把完整的程式碼放出來,都是投放了幾個方法,這裡把完整程式碼,和方法都投放

(因為我也不會寫原理,再不上程式碼,還TM寫個毛啊…)

到此結束,就是給在解決問題的道路上,家一個筆記而已