Question

我目前正在尝试为我的应用添加Android N支持。我使用新的Scoped Directory Access API在外部存储上读取应用的应用存储目录，如下所示：

public void requestExternalStoragePermissions(int requestCode) {
    StorageManager sm = (StorageManager)getContext().getSystemService(Context.STORAGE_SERVICE);
    StorageVolume volume = sm.getPrimaryStorageVolume();
    Intent intent = volume.createAccessIntent("MyApp");
    startActivityForResult(intent, requestCode);
}

但是，我在NullPointerException上获得了startActivityForResult：

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.content.Intent.migrateExtraStreamToClipData()' on a null object reference
    at android.app.Instrumentation.execStartActivity(Instrumentation.java:1635)
    at android.app.Activity.startActivityForResult(Activity.java:4858)
    at android.app.Activity.startActivityFromFragment(Activity.java:4844)
    at android.app.Activity$HostCallbacks.onStartActivityFromFragment(Activity.java:7125)
    at android.app.Fragment.startActivityForResult(Fragment.java:1150)
    at android.app.Fragment.startActivityForResult(Fragment.java:1139)
    ....

我做错了什么？

用户必须可以在文件管理器中轻松访问这些文件，因此getExternalFilesDir() NOT 是一个选项。

Answer 1

原来新的Scoped Directory Access API仅支持标准媒体目录（Documents，Music，Pictures等。

来自API reference for StorageVolume.createAccessIntent(String directoryName)：

directoryName：必须是DIRECTORY_MUSIC，DIRECTORY_PODCASTS，DIRECTORY_RINGTONES，DIRECTORY_ALARMS，DIRECTORY_NOTIFICATIONS，DIRECTORY_PICTURES之一{ {1}}，DIRECTORY_MOVIES，DIRECTORY_DOWNLOADS或DIRECTORY_DCIM或DIRECTORY_DOCUMENTS请求访问整个卷。

Scoped目录访问API抛出NullPointerException

1 个答案: