工具類--MD5Utils

public class MD5Utils {    private static final String[] HEX_DIGITS = { "0", "1", "2", "3", "4", "5",            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };    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();    }    private static String byteToHexString(byte b) {        int n = b;        if (n < 0) {         n += 256;      }        int d1 = n / 16;        int d2 = n % 16;        return HEX_DIGITS[d1] + HEX_DIGITS[d2];    }    /**     * 字符串MD5加密     * @param str     * @return     */    public static String encode(String str) throws Exception {        if (StringUtils.hasText(str)) {            return DigestUtils.md5DigestAsHex(str.getBytes());        }        return null;    }    public static String md5Encode(String origin, String charsetname) {        String resultString = null;        try {            resultString = new String(origin);            MessageDigest md = MessageDigest.getInstance("MD5");            if (charsetname == null || "".equals(charsetname)) {            resultString = byteArrayToHexString(md.digest(resultString                  .getBytes()));         } else {            resultString = byteArrayToHexString(md.digest(resultString                  .getBytes(charsetname)));         }        } catch (Exception exception) {        }        return resultString;    }}