java获取当前日期所在的周的周一，并以周一为一周开始

public String getMonday(String date) {

      if (date == null || date.equals("")) {

          System.out.println("date is null or empty");

          return "0000-00-00 00:00:00";

      }

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

      Date d = null;

      try  {

          d = format.parse(date);

      }

      catch(Exception e) {

          e.printStackTrace();

      }

      Calendar cal = Calendar.getInstance();

      cal.setTime(d);

      //set the first day of the week is Monday

      cal.setFirstDayOfWeek(Calendar.MONDAY);

      cal.set(Calendar.DAY_OF_WEEK,Calendar.MONDAY);

      return format.format(cal.getTime())+ " 00:00:00";

    }