getDir

/**
     * Retrieve, creating if needed, a new directory in which the application
     * can place its own custom data files.  You can use the returned File
     * object to create and access files in this directory.  Note that files
     * created through a File object will only be accessible by your own
     * application; you can only set the mode of the entire directory, not
     * of individual files.
     *
     * @param name Name of the directory to retrieve.  This is a directory
     * that is created as part of your application data.
     * @param mode Operating mode.  Use 0 or {@link #MODE_PRIVATE} for the
     * default operation, {@link #MODE_WORLD_READABLE} and
     * {@link #MODE_WORLD_WRITEABLE} to control permissions.
     *
     * @return A {@link File} object for the requested directory.  The directory
     * will have been created if it does not already exist.
     *
     * @see #openFileOutput(String, int)
     */
    public abstract File getDir(String name, int mode);

通過註釋我們可以看到這個方法是會在data/data/your pkg

創建一個目錄的，只有你自己的應用有權限訪問。

因而可以用這個方法快速創建一個data裏面的目錄。