文件MD5

*根据文件获取MD5

//获取单个文件的MD5的值
    public static String mD5(MultipartFile file)
    {
        if (file == null && StringUtil.isNull(file.getOriginalFilename()))
        {
            return null;
        }
        MessageDigest digest   = null;
        InputStream fis      = null;
        byte            buffer[] = new byte[1024];
        int             len;
        try
        {
            digest = MessageDigest.getInstance("MD5");
             fis = file.getInputStream();
            while ((len = fis.read(buffer, 0, 1024)) != -1)
            {
                digest.update(buffer, 0, len);
            }
        }
        catch (Exception e)
        {
            e.printStackTrace();
            return "";
        }
        finally
        {
            if (fis != null)
            {
                try
                {
                    fis.close();
                }
                catch (IOException e)
                {
                    e.printStackTrace();
                }
            }
        }
        return bytesToHexString(digest.digest());
    }

    private static String bytesToHexString(byte[] src)
    {
        if (src == null || src.length <= 0)
        {
            return null;
        }
        StringBuilder stringBuilder = new StringBuilder();
        for (byte aSrc : src)
        {
            int    v  = aSrc & 0xFF;
            String hv = Integer.toHexString(v);
            if (hv.length() < 2)
            {
                stringBuilder.append(0);
            }
            stringBuilder.append(hv);
        }
        return stringBuilder.toString();
    }