Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DATE, -1);
calendar.set(Calendar.HOUR_OF_DAY, 0);
calendar.set(Calendar.MINUTE,0);
calendar.set(Calendar.SECOND,0);
得到结果：昨天 00:00:00
例如：今天 2017-01-13 16:30:22
运行以上代码：2017-01-12 00:00:00