public class md5_test { //MD5的字符串常量 private final static String[] hexDigits = { "0", "1", "2", "3", "4",    "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" }; public static void main(String[] args) {    // TODO Auto-generated method stub    try {     MessageDigest messageDigest= MessageDigest.getInstance("MD5");     System.out.println(byteArrayToHexString(messageDigest.digest("baidu.com".getBytes())));    } catch (NoSuchAlgorithmException e) {     // TODO Auto-generated catch block     e.printStackTrace();    } } private static String byteArrayToHexString(byte[] b) {    StringBuffer resultSb = new StringBuffer();    for (int i = 0; i < b.length; i++) {     resultSb.append(byteToHexString(b[i]));    }    return resultSb.toString(); } /** 将一个字节转化成十六进制形式的字符串 */ private static String byteToHexString(byte b) {    int n = b;    if (n < 0)     n = 256 + n;    int d1 = n / 16;    int d2 = n % 16;    return hexDigits[d1] + hexDigits[d2]; } }

import org.apache.commons.codec.digest.DigestUtils; public class ToMain { public static void main(String[] args) {    System.out.println(DigestUtils.md5Hex("baidu.com")); } }