isSDCardEnable : 判斷SD卡是否可用
getSDCardPath  : 獲取SD卡路徑
getDataPath    : 獲取SD卡Data路徑
getFreeSpace   : 計算SD卡的剩餘空間
getSDCardInfo  : 獲取SD卡資訊


public class SDCardUtils {

    private SDCardUtils() {
        throw new UnsupportedOperationException("u can't instantiate me...");
    }

    /**
     * 判斷SD卡是否可用
     *
     * @return true : 可用<br>false : 不可用
     */
    public static boolean isSDCardEnable() {
        return Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState());
    }

    /**
     * 獲取SD卡路徑
     * <p>先用shell，shell失敗再普通方法獲取，一般是/storage/emulated/0/</p>
     *
     * @return SD卡路徑
     */
    public static String getSDCardPath() {
        if (!isSDCardEnable()) return "sdcard unable!";
        String cmd = "cat /proc/mounts";
        Runtime run = Runtime.getRuntime();
        BufferedReader bufferedReader = null;
        try {
            Process p = run.exec(cmd);
            bufferedReader = new BufferedReader(new InputStreamReader(new BufferedInputStream(p.getInputStream())));
            String lineStr;
            while ((lineStr = bufferedReader.readLine()) != null) {
                if (lineStr.contains("sdcard") && lineStr.contains(".android_secure")) {
                    String[] strArray = lineStr.split(" ");
                    if (strArray.length >= 5) {
                        return strArray[1].replace("/.android_secure", "") + File.separator;
                    }
                }
                if (p.waitFor() != 0 && p.exitValue() == 1) {
                    return " 命令執行失敗";
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            CloseUtils.closeIO(bufferedReader);
        }
        return Environment.getExternalStorageDirectory().getPath() + File.separator;
    }

    /**
     * 獲取SD卡data路徑
     *
     * @return SD卡data路徑
     */
    public static String getDataPath() {
        if (!isSDCardEnable()) return "sdcard unable!";
        return Environment.getExternalStorageDirectory().getPath() + File.separator + "data" + File.separator;
    }

    /**
     * 獲取SD卡剩餘空間
     *
     * @return SD卡剩餘空間
     */
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
    public static String getFreeSpace() {
        if (!isSDCardEnable()) return "sdcard unable!";
        StatFs stat = new StatFs(getSDCardPath());
        long blockSize, availableBlocks;
        availableBlocks = stat.getAvailableBlocksLong();
        blockSize = stat.getBlockSizeLong();
        return ConvertUtils.byte2FitSize(availableBlocks * blockSize);
    }

    /**
     * 獲取SD卡資訊
     *
     * @return SDCardInfo
     */
    @TargetApi(Build.VERSION_CODES.JELLY_BEAN_MR2)
    public static String getSDCardInfo() {
        SDCardInfo sd = new SDCardInfo();
        if (!isSDCardEnable()) return "sdcard unable!";
        sd.isExist = true;
        StatFs sf = new StatFs(Environment.getExternalStorageDirectory().getPath());
        sd.totalBlocks = sf.getBlockCountLong();
        sd.blockByteSize = sf.getBlockSizeLong();
        sd.availableBlocks = sf.getAvailableBlocksLong();
        sd.availableBytes = sf.getAvailableBytes();
        sd.freeBlocks = sf.getFreeBlocksLong();
        sd.freeBytes = sf.getFreeBytes();
        sd.totalBytes = sf.getTotalBytes();
        return sd.toString();
    }

    public static class SDCardInfo {
        boolean isExist;
        long    totalBlocks;
        long    freeBlocks;
        long    availableBlocks;
        long    blockByteSize;
        long    totalBytes;
        long    freeBytes;
        long    availableBytes;

        @Override
        public String toString() {
            return "isExist=" + isExist +
                    "\ntotalBlocks=" + totalBlocks +
                    "\nfreeBlocks=" + freeBlocks +
                    "\navailableBlocks=" + availableBlocks +
                    "\nblockByteSize=" + blockByteSize +
                    "\ntotalBytes=" + totalBytes +
                    "\nfreeBytes=" + freeBytes +
                    "\navailableBytes=" + availableBytes;
        }
    }
}