Java 日历类 Calendar 相关方法

    /**       * 计算指定日期为当年第几周       * @param year  指定的年份       * @param month  指定的月份       * @param day  指定的日       * @return   指定日期为当年的第几周       */      public static int caculateWeekOfYear(int year,int month,int day){       Calendar c = Calendar.getInstance();       c.set(Calendar.YEAR, year);       c.set(Calendar.MONTH, month - 1);       c.set(Calendar.DATE, day);       return c.get(Calendar.WEEK_OF_YEAR);      }            /**       * 获取本月第一天是星期几       * @return       */      public static int getWeekOfFirstDay(Calendar c){       Calendar calendar = c;       calendar.set(Calendar.DAY_OF_MONTH, 1);       return calendar.get(Calendar.DAY_OF_WEEK);      }            /**       * 获取本月1号是该年的第几周       * @return       */      public static int getMonthStartWeek(Calendar c){       Calendar calendar = c;       calendar.set(Calendar.DATE, 1);       return calendar.get(Calendar.WEEK_OF_YEAR);      }            /**       * 获取当天是该年的第几周       */      public static int getCurrentWeekOfYear(){       Calendar calendar = Calendar.getInstance();       return calendar.get(Calendar.WEEK_OF_YEAR);      }            /**       * 获取上月的总天数       * @return       */      public static int getLastMonthDays(Calendar c){       Calendar calendar = c;       calendar.set(Calendar.MONTH, calendar.get(Calendar.MONTH) - 1);       return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);      }            /**       * 获取指定月份的总天数       * @return       */      public static int getCurrentMonthDays(int month){       Calendar c = Calendar.getInstance();       c.set(Calendar.MONTH, month);       return c.getActualMaximum(Calendar.DAY_OF_MONTH);      }            /**       * 获取指定年份有多少周       * @param year       * @return       */      public static int getTotalWeekOfYear(int year){       Calendar c = Calendar.getInstance();       return c.getActualMaximum(Calendar.WEEK_OF_YEAR);      }            /**       * 判断指定月份是否是当前月       * @param month       * @return       */      public static boolean isCurrentMonth(int month){    Calendar c = Calendar.getInstance();    return (c.get(Calendar.MONTH) == month)?true:false;   }            /**       * 计算指定的月份共有多少天       */      public static int getTotalDaysOfMonth(int year, int month){       Calendar c = Calendar.getInstance();    c.set(Calendar.YEAR, year);    c.set(Calendar.MONTH, month);    c.set(Calendar.DATE, 1);    /**     * 计算这个月有多少天     */    return c.getActualMaximum(Calendar.DAY_OF_MONTH);      }