通过createDeviceProtectedStorageContext建立的SharePreference的存储位置

关于Direct Boot Mode［DBM］介绍可以参考如下文章
http://blog.csdn.net/huluboy/article/details/53397582

一般应用的SharePreference保存在/data/data/[package name]/shared_prefs目录，但通过createDeviceProtectedStorageContext建立的SharePreference是保存在/data/user_de/0/[package name]/shared_prefs目录。

当我们找不到SharePreference保存在哪，可以通过这个方法获取其路径

final File source = deviceContext.getSharedPreferencesPath(PreferenceManager.getDefaultSharedPreferencesName(deviceContext));
String absolutePath = source.getAbsolutePath();

使用例子是DeskClock
http://androidxref.com/7.1.1_r6/xref/packages/apps/DeskClock/src/com/android/deskclock/Utils.java

/**
* Return the default shared preferences.
*/
public static SharedPreferences getDefaultSharedPreferences(Context context) {
    final Context storageContext;
    if (isNOrLater()) {
        / All N devices have split storage areas, but we may need to
        // migrate existing preferences into the new device protected
        // storage area, which is where our data lives from now on.
        final Context deviceContext = context.createDeviceProtectedStorageContext();
            if (!deviceContext.moveSharedPreferencesFrom(context,
                    PreferenceManager.getDefaultSharedPreferencesName(context))) {
                LogUtils.wtf("Failed to migrate shared preferences");
            }
           storageContext = deviceContext;
        } else {
            storageContext = context;
        }

        return PreferenceManager.getDefaultSharedPreferences(storageContext);
    }
}