用Calendar方法知道月份的天数

package test;


import java.math.BigDecimal;
import java.nio.channels.NonReadableChannelException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.*;

public class Main {

	private static final String space_operator = " ";
	private static final double pi = Math.PI;
	public static void main(String[] args) throws Exception {

		
		
		Calendar c = Calendar.getInstance();
		
		/*
		 * 获取当前时间
		 */
		showDate(c);
		
		/*
		 * 获取昨天的这个时间段
		 */
		c.add(Calendar.DAY_OF_MONTH, -1);
		showDate(c);
		
		/*
		 * 想知道每年的二月份有多少天
		 */
		february(2013);
	}
	
	/**
	 * @param year
	 * 我们直接找出三月一号；
	 * 然后向下偏移一天就是二月的最后一天
	 * 直接用c.get方法输出
	 * 需要注意的是月份是从0开始的
	 */
	public static void february(int year) {
		Calendar c = Calendar.getInstance();
		c.set(year, 2, 1);
		c.add(Calendar.DAY_OF_MONTH, -1);
		
		System.out.println(c.get(Calendar.DAY_OF_MONTH));
	}
	public static void showDate(Calendar c) {
		int year = c.get(Calendar.YEAR);
		int month = c.get(Calendar.MONTH) + 1;
		int day = c.get(Calendar.DAY_OF_MONTH);
		int week = c.get(Calendar.DAY_OF_WEEK);
	
		System.out.println(year + "年" + month + "月" + day +  "日" + getweek(week));
	}
	
	public static String getweek(int week) {
		String [] weeks = {"","星期日","星期一","星期二","星期三","星期四","星期五","星期六"};
				
		return weeks[week];
	}
	
}