public static String md5(String resource) {
    // 1.判断resource是否有效
    if(resource.length()==0||resource==null){
        //2.抛出异常
      throw  new RuntimeException(CrowdConstant.MESSAGE_STRING_INVALIDATE);
    }
    try {
        // 3.获取MessageDigest对象
        String way="md5";
     MessageDigest messageDigest=   MessageDigest.getInstance(way);
        //获取资源对应的字节数组
        byte[] bytes=resource.getBytes();
        //执行加密
     byte[] output=   messageDigest.digest(bytes);
     //创建bigInteger对象
        int sginnum=1;
        BigInteger bigInteger=new BigInteger(sginnum,output);
        //按照16进制将BigInteger对象转化成字符串
        int radix=16;
        String  code=bigInteger.toString(radix);
        return  code;
    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    }
    return  null;
}
结果：