Android 4.2 获取应用缓存接口变化

PackageManager.getPackageSizeInfo(String packageName, IPackageStatsObserver observer)不可用，改为PackageManager.getPackageSizeInfo(String packageName, int userHandle, IPackageStatsObserver observer), 至于增加的参数userHandle的解释是：The user whose size information should be retrieved。下面是PackageManager内部的用法：

因此，把UserHandle.myUserId()的实作部分整合进来就可用了：

private void getPacakgeStats(String pkgName) {
    if (pkgName != null) {
        try {
            Method getPackageSizeInfo = mPm.getClass().getDeclaredMethod("getPackageSizeInfo", String.class,
                    int.class, IPackageStatsObserver.class);
            /**
             * after invoking, PkgSizeObserver.onGetStatsCompleted() will be called as callback function. <br>
             * About the third parameter ‘Process.myUid() / 100000’，please check:
             * <android_source>/frameworks/base/core/java/android/content/pm/PackageManager.java:
             * getPackageSizeInfo(packageName, UserHandle.myUserId(), observer);
             */
            getPackageSizeInfo.invoke(mPm, pkgName, Process.myUid() / 100000, new PkgSizeObserver());
        } catch (Exception e) {
            Log.e(TAG, e.toString());
        }
    }
}