44.Android MD5Util

public class MD5Util {

    public static String getMD5String(String key) {

        char hexDigits[] = {'0', '1', '2', '3', '4',

                '5', '6', '7', '8', '9',

                'A', 'B', 'C', 'D', 'E', 'F'};

        try {

            byte[] input = key.getBytes();

            // MD5算法的 MessageDigest 对象

            MessageDigest md5Digest = MessageDigest.getInstance("MD5");

            // 转换

            md5Digest.update(input);

            // 密文

            byte[] md5byte = md5Digest.digest();

            // string 转 十六进制

            int j = md5byte.length;

            char md5char[] = new char[j * 2];

            int k = 0;

            for (byte b : md5byte) {

                md5char[k++] = hexDigits[b >>> 4 & 0xf];

                md5char[k++] = hexDigits[b & 0xf];

            }

            return new String(md5char);

        } catch (Exception e) {

            e.printStackTrace();

            return null;

        }

    }

    private static String bytesToHexString(byte[] bytes) {

        StringBuilder sb = new StringBuilder();

        for (byte aByte : bytes) {

            String hex = Integer.toHexString(255 & aByte);

            if (hex.length() == 1) {

                sb.append('0');

            }

            sb.append(hex);

        }

        return sb.toString();

    }

}