android 使用MD5加密文件

private static final int STREAM_BUFFER_LENGTH = 1024;
private static final String ALGORITHM_MD5 = "MD5";

public static String md5File(File file) {

        if (null == file) {

            return "";

        }

        String result = "";

        try {

            MessageDigest digest = MessageDigest.getInstance(ALGORITHM_MD5);

            byte[] digests = updateDigest(digest, new FileInputStream(file)).digest();

            BigInteger bi = new BigInteger(1, digests);

            result = bi.toString(16);

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

        } catch (FileNotFoundException e) {

            e.printStackTrace();

        } catch (IOException e) {

            e.printStackTrace();

        }

        return result;

    }



    public static MessageDigest updateDigest(final MessageDigest digest, final InputStream data) throws IOException {

        final byte[] buffer = new byte[STREAM_BUFFER_LENGTH];

        int read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);



        while (read > -1) {

            digest.update(buffer, 0, read);

            read = data.read(buffer, 0, STREAM_BUFFER_LENGTH);

        }

        return digest;

    }