Calendar expireDate = Calendar.getInstance();
expireDate.set(Calendar.HOUR_OF_DAY, expireDate.get(Calendar.HOUR_OF_DAY)-20);
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//expireDate.add(Calendar.DAY_OF_MONTH, -7);//获取七天前的时间
System.out.println(df.format(expireDate.getTime()));
System.out.println(df.format(new Date()));如代码,主要通过Calendar类来实现,还可以获取当期时间前几天的时间(注释部分,去掉上面的SET) 更多详细用法看Calendar的api 。原文地址:http://blog.csdn.net/xiaopeng187/article/details/46424809