16位MD5加密JAVA版

import java.security.MessageDigest;import java.security.NoSuchAlgorithmException;class MD5Security {private final static char[] hexDigits = { '0', '1', '2', '3', '4', '5','6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };private static String bytesToHex(byte[] bytes) {StringBuffer sb = new StringBuffer();int t;for (int i = 0; i < 16; i++) {t = bytes[i];if (t < 0)t += 256;sb.append(hexDigits[(t >>> 4)]);sb.append(hexDigits[(t % 16)]);}return sb.toString();}public static String md5(String input) throws Exception {return code(input, 32);}public static String code(String input, int bit) throws Exception {try {MessageDigest md = MessageDigest.getInstance(System.getProperty("MD5.algorithm", "MD5"));if (bit == 16)return bytesToHex(md.digest(input.getBytes("utf-8"))).substring(8, 24);return bytesToHex(md.digest(input.getBytes("utf-8")));} catch (NoSuchAlgorithmException e) {e.printStackTrace();throw new Exception("Could not found MD5 algorithm.", e);}}public static String md5_3(String b) throws Exception{MessageDigest md = MessageDigest.getInstance(System.getProperty("MD5.algorithm", "MD5"));byte[] a = md.digest(b.getBytes());a = md.digest(a);a = md.digest(a);return bytesToHex(a);}}