get Android device's all external storage

StorageUtil.java

import android.annotation.SuppressLint;
import android.content.Context;
import android.os.Build;
import android.os.StatFs;
import android.os.storage.StorageManager;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Scanner;

public class StorageUtil {
    private final static int MAX_EXTERNAL_STORAGE_NUM = 4;
    private final static String VOLUME_MOUNTED_STATE = "mounted";

    public static ArrayList<String> getAllExternalStorages(Context context) {
        ArrayList<String> pathList = new ArrayList<String>(MAX_EXTERNAL_STORAGE_NUM);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            pathList = getExternalPaths(context);
        } else if (Build.VERSION.SDK_INT > Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
            pathList = getVolumePaths(context);
        } else {
            pathList = filterExternalPaths();
        }
        return pathList;
    }

    @SuppressWarnings("deprecation")
    public static long getAvailableSpace(String path) {
        StatFs statFs = new StatFs(path);
        long blockSize = statFs.getBlockSize();
        long availableBlocks = statFs.getAvailableBlocks();
        return blockSize * availableBlocks;
    }

    @SuppressLint("NewApi")
    private static ArrayList<String> getExternalPaths(Context context) {
        File[] externalFiles = context.getExternalFilesDirs(null);
        int len = externalFiles.length + 1;
        ArrayList<String> externalPathList = new ArrayList<String>(len);
        for (File externalFile : externalFiles) {
            if (externalFile != null && externalFile.exist()) {
                externalPathList.add(externalFile.getPath());
            }
        }
        return externalPathList;
    }
    
    private static ArrayList<String> getVolumePaths(Context context) {
        StorageManager sm = (StorageManager) context.getSystemService(Context.STORAGE_SERVICE);
        ArrayList<String> pathList = new ArrayList<String>(MAX_EXTERNAL_STORAGE_NUM);
        try {
            Method getListMethod = StorageManager.class.getMethod("getVolumePaths");
            String[] volumeList = (String[]) getListMethod.invoke(sm);
            if (volumeList != null) {
                for (int i = 0; i < volumeList.length; i++) {
                    Method volumeMethod = StorageManager.class.getMethod("getVolumeState", String.class);
                    String path = volumeList[i];
                    String volumeState = (String) volumeMethod.invoke(sm, path);
                    if (VOLUME_MOUNTED_STATE.equals(volumeState) && !pathList.contains(path)) {
                        pathList.add(path);
                    }
                }
            }
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalAccessException e) {
            e.printStackTrace();
        } catch (InvocationTargetException e) {
            e.printStackTrace();
        } catch (NoSuchMethodException e) {
            e.printStackTrace();
        }
        return pathList;
    }

    private static ArrayList<String> filterExternalPaths() {
        ArrayList<String> procMountList = getProcMounts();
        List<String> mountPointList = getMountPoints();
        Iterator<String> iterator = procMountList.iterator();
        while (iterator.hasNext()) {
            String mountPoint = iterator.next();
            if (!mountPointList.contains(mountPoint)) {
                iterator.remove();
            }
        }
        return procMountList;
    }

    private static ArrayList<String> getMountPoints() {
        ArrayList<String> mountPointList = new ArrayList<String>();
        File voldFstab = new File("/system/etc/vold.fstab");
        Scanner scanner = null;
        try {
            scanner = new Scanner(new FileInputStream(voldFstab));
            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                if (line.startsWith("dev_mount") || line.startsWith("fuse_mount")) {
                    String[] lineSplits = line.split("\\s+");
                    String mountPoint = lineSplits[2];
                    if (mountPoint.contains(":")) {
                        mountPoint = mountPoint.substring(0, mountPoint.indexOf(":"));
                    }
                    mountPointList.add(mountPoint);
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (scanner != null) scanner.close();
        }
        return mountPointList;
    }

    private static ArrayList<String> getProcMounts() {
        ArrayList<String> procMountList = new ArrayList<String>();
        File procMounts = new File("/proc/mounts");
        Scanner scanner = null;
        try {
            scanner = new Scanner(new FileInputStream(procMounts));
            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                if (line.startsWith("/dev/block") && !line.contains("asec")) {
                    String[] lineSplits = line.split("\\s+");
                    String procMount = lineSplits[1];
                    if (!procMountList.contains(procMount)) {
                        procMountList.add(procMount);
                    }
                }
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally {
            if (scanner != null) scanner.close();
        }
        return procMountList;
    }
}