一个获取本周、本月、上月、当天日期的工具

 /**
     * 获取本月、本周、当天
     */
    public String getTimeStr(Calendar calendar, String type){
        StringBuffer sbr = new StringBuffer();
        try {
            SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
            if("month".equals(type)){
                calendar.setTime(new Date());
                Calendar start = getInstance();
                Calendar end = getInstance();
                //当前月份第一天
                start.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH ),
                        calendar.getActualMinimum(Calendar.DAY_OF_MONTH), 0, 0, 0);
                sbr.append(format.format(start.getTime())).append("&");
                //当前月份最后一天
                end.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH ),
                        calendar.getActualMaximum(Calendar.DAY_OF_MONTH), 23, 59, 59);
                sbr.append(format.format(end.getTime()));
            }else if("week".equals(type)){
                calendar.setTime(new Date());
                // 获得当前日期是一个星期的第几天
                int dayWeek = calendar.get(Calendar.DAY_OF_WEEK);
                if (1 == dayWeek) {
                    calendar.add(Calendar.DAY_OF_MONTH, -1);
                }
                calendar.setFirstDayOfWeek(Calendar.MONDAY);
                // 获得当前日期是一个星期的第几天
                int day = calendar.get(Calendar.DAY_OF_WEEK);
                calendar.add(Calendar.DATE, calendar.getFirstDayOfWeek() - day);
                calendar.set(HOUR_OF_DAY, 0);
                calendar.set(SECOND, 0);
                calendar.set(MINUTE, 0);
                calendar.set(MILLISECOND, 0);
                sbr.append(format.format(calendar.getTime())).append("&");
                calendar.add(Calendar.DAY_OF_WEEK, 6);
                calendar.set(HOUR_OF_DAY, 23);
                calendar.set(SECOND, 59);
                calendar.set(MINUTE, 59);
                calendar.set(MILLISECOND, 999);
                sbr.append(format.format(calendar.getTime()));
            }else if("day".equals(type)){
                sbr.append(format.format(calendar.getTime()));
            }else if("lastMonth".equals(type)){
                calendar.setTime(new Date());
                Calendar start = getInstance();
                calendar.add(Calendar.MONTH, -1);
                calendar.set(Calendar.DAY_OF_MONTH, 1);
                //上月份第一天
                start.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
                        calendar.getActualMinimum(Calendar.DAY_OF_MONTH), 0, 0, 0);
                sbr.append(format.format(start.getTime())).append("&");
                Calendar end = getInstance();
                int month= end.get(Calendar.MONTH);
                calendar.set(Calendar.MONTH, month-1);
                calendar.set(Calendar.DAY_OF_MONTH, end.getActualMaximum(Calendar.DAY_OF_MONTH));
                //上月份最后一天
                end.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH ),
                        calendar.getActualMaximum(Calendar.DAY_OF_MONTH), 23, 59, 59);
                sbr.append(format.format(end.getTime()));
            }
        } catch (Exception e) {
            logger.error("getTimeStr获取日期报错{}",e.getMessage());
        }
        return String.valueOf(sbr);
    }