使用java.util.Date 当前系统时间减一个月

SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
Date endDate=new Date();
System.out.println(sdf.format(endDate)+"=================");
Calendar date=Calendar.getInstance();
date.setTime(endDate);
date.set(Calendar.MONTH, date.get(Calendar.MONTH)-1);
Date startDate=null;
try {
startDate = sdf.parse(sdf.format(date.getTime()));
} catch (ParseException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}