java获取当月天数，指定年月的天数，指定日期获取对应星期

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