java日期得到月天数.docx

java得到当月天数1.使用calendar类实现/* 取得当月天数* */public static int getCurrentMonthLastDay()Calendar a = Calendar.getInstance();a.set(Calendar.DATE, 1);/把日期设置为当月第一天a.roll(Calendar.DATE, -1);/日期回滚一天，也就是最后一天int maxDate = a.get(Calendar.DATE);return maxDate;/* 得到指定月的天数* */public static int getMonthLastDay(int year, int month)Calendar a = Calendar.getInstance();a.set(Calendar.YEAR, year);a.set(Calendar.MONTH, month - 1);a.set(Calendar.DATE, 1);/把日期设置为当月第一天a.roll(Calendar.DATE, -1);/日期回滚一天，也就是最后一天int maxDate = a.get(Calendar.DATE);return maxDate;2.使用自己编写的函数实现package test;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;/* 日期工具类 by hpf* */public class DateUtils/返回当前年月日String getNowDate()Date date = new Date();String nowDate = new SimpleDateFormat(yyyy年MM月dd日).format(date);return nowDate;/返回当前年份int getYear()Date date = new Date();String year = new SimpleDateFormat(yyyy).format(date);return Integer.parseInt(year);/返回当前月份int getMonth()Date date = new Date();String month = new SimpleDateFormat(MM).format(date);return Integer.parseInt(month);/判断闰年boolean isLeap(int year)if (year % 100 = 0) & year % 400 = 0) | (year % 100 != 0) & year % 4 = 0)return true;elsereturn false;/返回当月天数int getDays(int year, int month)int days;int FebDay = 28;if (isLeap(year)FebDay = 29;switch (month)case 1:case 3:case 5:case 7:case 8:case 10:case 12:days = 31;break;case 4:case 6:case 9:case 11:days = 30;break;case 2:days = FebDay;break;default:days = 0;break;return days;/返回当月星期天数int getSundays(int year, int month)int sundays = 0;SimpleDateFormat sdf = new SimpleDateFormat(EEEE);Calendar setDate = Calendar.getInstance();/从第一天开始int day;for (day = 1; day = getDays(year, month); day+)setDate.set(Calendar.DATE, day);String str = sdf.format(setDate.getTime();if (str.equals(星期日)sundays+;return sundays;public static void main(String args)DateUtils du = new DateUtils();System.out.println(今天日期是： + du.getNowDate();System.out.println(本月有 + du.getDays(du.ge