一个md5加密的工具类，用的虚拟机的包，不需要额外导包

package com.yun.park.service.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.security.MessageDigest;

/**
 * Created by asus on 2016/12/12.
 */
public class MD5 {
    private static Logger logger = LoggerFactory.getLogger(MD5.class);
    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

    /**
     * 转换字节数组为16进制字串
     *
     * @param b
     *            字节数组
     * @return 16进制字串
     */
    public 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 + n;
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }

    public static String MD5Encode(String paramStr) {
        String resultString = paramStr;
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            resultString = byteArrayToHexString(md.digest(resultString
                    .getBytes()));
        } catch (Exception ex) {
            logger.debug("MD5Encode = {}",ex);
        }
        return resultString;
    }
}