//通过用户名+时间+MD5生成动态秘钥

 public String getSecretKey(ZcUserbase user){
         String secretKey = UUID.randomUUID().toString(); // 密钥
         Timestamp outDate = new Timestamp(System.currentTimeMillis() + 30 * 60 * 1000);// 30分钟后过期
         long date = outDate.getTime() / 1000 * 1000;// 忽略毫秒数  mySql 取出时间是忽略毫秒数的
         String key =user.getNickname() + "$" + date + "$" + secretKey;
         String digitalSignature = MD5Utils.md5(key);// 数字签名
        return digitalSignature;

//应用场景
//忘记密码激活邮箱 并在邮箱生成一个code 32位的秘钥

ZcUserbase user=new ZcUserbase();
            user.setNickname(nickname);
            ZcUserbase account=userService.QueryAccount(user);
            if(account!=null){
                //生成数字签名
                String digitalSignature=getSecretKey(user);
                //设置数字签名
                account.setCode(digitalSignature);
                 this.userService.edit(account);                 
                //发送激活邮件
                boolean temp=SendMail.sendMsg(account.getMailbox(), account.getCode());
                if(temp==true){
                    return Commons.EMAILSUCCESS;
                }else{
                    return Commons.EMAILERROR;
                }