java中 时间加减法
SimpleDateFormat format3 = new SimpleDateFormat("yyyy-MM-dd-HH:mm:ss");
//增加2小时
Calendar rightNow = Calendar.getInstance();
//Calendar 里面有各种年月日的加减法
rightNow.setTime(new Date());
rightNow.add(Calendar.HOUR, 2);
Date dt1=rightNow.getTime();
//转化String 为日期
String reStr = format3.format(dt1);