您无权直接访问外部存储不可移动存储.

You do not have direct filesystem access to arbitrary locations on removable storage, starting with Android 4.4. WRITE_EXTERNAL_STORAGE is meaningless here, as external storage is not removable storage.

改用Storage Access Framework(ACTION_OPEN_DOCUMENT_TREE和kin).或者，将您的工作限制为作为getExternalFilesDirs()，getExternalCacheDirs()和getExternalMediaDirs()的一部分返回的可移动存储位置(Context上的所有方法).

Use the Storage Access Framework (ACTION_OPEN_DOCUMENT_TREE and kin) instead. Or, limit your work to the removable storage locations returned as part of getExternalFilesDirs(), getExternalCacheDirs(), and getExternalMediaDirs() (all methods on Context).