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;
}
}