SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");//设置日期格式此时表示（年月日），其格式 还可以为yyyy-MM-dd HH:mm:ss精确到秒

 String date = df.format(new java.util.Date());    //获取系统时间，并按照设置的时间格式得到时间字符串

 Date date2 = Date.valueOf(date);     //将代表时间的字符串转化为Date类型

 Calendar c = Calendar.getInstance();

 int year = c.get(Calendar.YEAR);

 int month = c.get(Calendar.MONTH);

 int date = c.get(Calendar.DATE);

 int hour = c.get(Calendar.HOUR_OF_DAY);

 int minute = c.get(Calendar.MINUTE);

 int second = c.get(Calendar.SECOND); 
String date1 = ""  + year + ":" + month + ":" + date + ":" + hour + ":" + minute + ":" + second; 

SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

java.util.Date time= sdf.parse(sdf.format(new Date()));