[Android] 현재 마운트된 SD카드 리스트

public String[] getExternalStorageDirectories() {
    List<String> results = new ArrayList<>();
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) { //Method 1 for KitKat & above
        File[] externalDirs = getExternalFilesDirs(null);
        for (File file : externalDirs) {
            String path = file.getPath().split("/Android")[0];
            boolean addPath = false;
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
                addPath = Environment.isExternalStorageRemovable(file);
            } else {
                addPath = Environment.MEDIA_MOUNTED.equals(EnvironmentCompat.getStorageState(file));
            }
            if (addPath) {
                results.add(path);
            }
        }
    }

    if (results.isEmpty()) { //Method 2 for all versions
        // better variation of: http://stackoverflow.com/a/40123073/5002496
        String output = "";
        try {
            final Process process = new ProcessBuilder().command("mount | grep /dev/block/vold").redirectErrorStream(true).start();
            process.waitFor();
            final InputStream is = process.getInputStream();
            final byte[] buffer = new byte[1024];
            while (is.read(buffer) != -1) {
                output = output + new String(buffer);
            }
            is.close();
        } catch (final Exception e) {
            e.printStackTrace();
        }
        if (!output.trim().isEmpty()) {
            String devicePoints[] = output.split("\n");
            for (String voldPoint : devicePoints) {
                results.add(voldPoint.split(" ")[2]);
            }
        }
    } //Below few lines is to remove paths which may not be external memory card, like OTG (feel free to comment them out)
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        for (int i = 0; i < results.size(); i++) {
            if (!results.get(i).toLowerCase().matches(".*[0-9a-f]{4}[-][0-9a-f]{4}")) {
                Log.d(LOG_TAG, results.get(i) + " might not be extSDcard");
                results.remove(i--);
            }
        }
    } else {
        for (int i = 0; i < results.size(); i++) {
            if (!results.get(i).toLowerCase().contains("ext") && !results.get(i).toLowerCase().contains("sdcard")) {
                Log.d(LOG_TAG, results.get(i) + " might not be extSDcard");
                results.remove(i--);
            }
        }
    }
    String[] storageDirectories = new String[results.size()];
    for (int i = 0; i < results.size(); ++i) storageDirectories[i] = results.get(i);
    return storageDirectories;
}