android 代码问题

Question

 public static File[] getDownloadDirs(String subDir) {
        Context context = XposedApp.getInstance();
        ArrayList<File> dirs = new ArrayList<>(2);
        for (File dir : ContextCompat.getExternalCacheDirs(context)) {
            if (dir != null && EnvironmentCompat.getStorageState(dir).equals(Environment.MEDIA_MOUNTED)) {
                dirs.add(new File(new File(dir, "downloads"), subDir));
            }
        }
        dirs.add(new File(new File(context.getCacheDir(), "downloads"), subDir));
        return dirs.toArray(new File[dirs.size()]);
    }

ContextCompat.getExternalCacheDirs(context)) 这是对应手机哪个目录？
EnvironmentCompat.getStorageState(dir).equals(Environment.MEDIA_MOUNTED) 这个代码啥意思？