public class MD5_Test {

    public static String md5_1(String oldStr) {

        char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' };

        try {

            byte[] oldBytes = oldStr.getBytes();

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

            md.update(oldBytes);

            byte[] newBytes = md.digest();

            char newStr[] = new char[32];

            for (int i = 0; i < 16; i++) {

                byte tmp = newBytes[i];

                newStr[2 * i] = hexDigits[tmp >>> 4 & 0xf];

                newStr[2 * i + 1] = hexDigits[tmp & 0xf];

            }

            return new String(newStr);

        } catch (Exception e) {

            return null;

        }

    }

    public static String md5_2(String oldStr) {

        try {

            MessageDigest digest = MessageDigest.getInstance("md5");

            byte[] bs = digest.digest(oldStr.getBytes());

            String hexString = "";

            for (byte b : bs) {

                int temp = b & 255;

                if (temp < 16 && temp >= 0) {

                    hexString = hexString + "0" + Integer.toHexString(temp);

                } else {

                    hexString = hexString + Integer.toHexString(temp);

                }

            }

            return hexString;

        } catch (NoSuchAlgorithmException e) {

            e.printStackTrace();

        }

        return "";

    }

    public static String md5_3(String plainText) throws NoSuchAlgorithmException {

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

        md.update(plainText.getBytes());

        byte b[] = md.digest();

        int i;

        StringBuffer buf = new StringBuffer("");

        for (int offset = 0; offset < b.length; offset++) {

            i = b[offset];

            if (i < 0)

                i += 256;

            if (i < 16)

                buf.append("0");

            buf.append(Integer.toHexString(i));

        }

        return buf.toString();

        // System.out.println("result: " + buf.toString());//32位的加密

        // System.out.println("result: " + buf.toString().substring(8,24));//16位的加密

    }

    public static String EncoderByMd5(String str) throws NoSuchAlgorithmException, UnsupportedEncodingException {

        // 确定计算方法

        MessageDigest md5 = MessageDigest.getInstance("MD5");

        BASE64Encoder base64en = new BASE64Encoder();

        // 加密后的字符串

        String newstr = base64en.encode(md5.digest(str.getBytes("utf-8")));

        return newstr;

    }

    public static void main(String[] args) throws NoSuchAlgorithmException, UnsupportedEncodingException {

        System.out.println(md5_1("1"));

        System.out.println(md5_2("1"));

        System.out.println(md5_2("1"));

    }

}