获得内部存储android的可用空间

Question

如何获取android内部存储的可用空间，例如Photos或Download的文件夹...更具体，我需要访问由另一个应用程序创建的库的文件夹是WhatsApp照片文件夹。我是Android移动开发人员的新手，该公司认为这是一个挑战。我看到了一些技术，但他们只说了如何处理SD卡，我不知道如何申请INTERNAL模式。有人能帮助我吗？

提前谢谢。

File [] externalStorageFiles = ContextCompat.getExternalFilesDirs (this, null);

            / **
             * We get the external directory
             * /
             File externalStorageDirectory = Environment.getExternalStorageDirectory ();

          

            / **
             * We take the folder (Here you must enter the path you want)
             * /
             File downloadFolder = new File (externalStorageDirectory.getAbsolutePath () + "/ Download");


            / **
             * If directory exists
             * /
            If (downloadFolder.exists ()) {

                / **
                 * Messages with folder information
                 * /

                Toast.makeText (getApplicationContext (), downloadFolder.getUsableSpace () + "bytes used", Toast.LENGTH_SHORT) .show ();
                Toast.makeText (getApplicationContext (), downloadFolder.getFreeSpace () + "free bytes", Toast.LENGTH_SHORT) .show ();
                Toast.makeText (getApplicationContext (), downloadFolder.getTotalSpace () + "total bytes", Toast.LENGTH_SHORT) .show ();

                If (null! = Folder.listFiles ()) {
                    Toast.makeText (getApplicationContext (), folder.listFiles (). Length + "files", Toast.LENGTH_SHORT) .show ();
                }

            } Else {
                Toast.makeText (getApplicationContext (), "Directory does not exist", Toast.LENGTH_SHORT) .show ();

            }