package com;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;/** * @author Gerrard */public class TestGetWeek {	public static void main(String[] args) {		int currentMaxDays = getCurrentMonthDay();				int maxDaysByDate = getDaysByYearMonth(2012, 11);				String week = getDayOfWeekByDate("2012-12-25");				System.out.println("本月天数：" + currentMaxDays);		System.out.println("2012年11月天数：" + maxDaysByDate);		System.out.println("2012-12-25是：" + week);	}		/**	 * 获取当月的 天数	 * */	public static int getCurrentMonthDay() {				Calendar a = Calendar.getInstance();		a.set(Calendar.DATE, 1);		a.roll(Calendar.DATE, -1);		int maxDate = a.get(Calendar.DATE);		return maxDate;	}	/**	 * 根据年 月 获取对应的月份 天数	 * */	public static int getDaysByYearMonth(int year, int month) {				Calendar a = Calendar.getInstance();		a.set(Calendar.YEAR, year);		a.set(Calendar.MONTH, month - 1);		a.set(Calendar.DATE, 1);		a.roll(Calendar.DATE, -1);		int maxDate = a.get(Calendar.DATE);		return maxDate;	}		/**	 * 根据日期 找到对应日期的 星期	 */	public static String getDayOfWeekByDate(String date) {		String dayOfweek = "-1";		try {			SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");			Date myDate = myFormatter.parse(date);	      	SimpleDateFormat formatter = new SimpleDateFormat("E");	      	String str = formatter.format(myDate);	      	dayOfweek = str;	      			} catch (Exception e) {			System.out.println("错误!");		}		return dayOfweek;	}}

 转：http://blog.csdn.net/delongcpp/article/details/8435656