1、取得指定日期是星期几
取得指定日期是星期几可以采用下面两种方式取得日期是星期几：
a、使用Calendar类
[java]
//根据日期取得星期几
public static String getWeek(Date date){
String[] weeks = {"星期日","星期一","星期二","星期三","星期四","星期五","星期六"};
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int week_index = cal.get(Calendar.DAY_OF_WEEK) - 1;
if(week_index<0){
week_index = 0;
}
return weeks[week_index];
}
b、使用SimpleDateFormat类
[java]
//根据日期取得星期几
public static String getWeek(Date date){
SimpleDateFormat sdf = new SimpleDateFormat("EEEE");
String week = sdf.format(date);
return week;
}
注：格式化字符串存在区分大小写
对于创建SimpleDateFormat传入的参数：EEEE代表星期，如“星期四”；MMMM代表中文月份，如“十一月”；MM代表月份，如“11”；
yyyy代表年份，如“2010”；dd代表天，如“25”
2、取得日期是某年的第几周
根据日期入得日期是某年的第几周。
[java]
//取得日期是某年的第几周
public static int getWeekOfYear(Date date){
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int week_of_year = cal.get(Calendar.WEEK_OF_YEAR);
return week_of_year;
}
3、得到某年的某个月有多少天
已知年份和月份，取得该月有多少天。
[java]
//取得某个月有多少天
public static int getDaysOfMonth(int year,int month){
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, year);
cal.set(Calendar.MONTH, month-1);
int days_of_month = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
return days_of_month;
}
4、取得两个日期之间的相差多少天
已知两个日期，计算它们之间相差多少天。
[java]
<pre name="code" class="java">// 取得两个日期之间的相差多少天
public static long getDaysBetween(Date date0, Date date1) {
long daysBetween = (date0.getTime() - date1.getTime() + 1000000) / 86400000;// 86400000=3600*24*1000 用立即数，减少乘法计算的开销
return daysBetween;
}
5、完整的测试代码
[java]
package org.ml.test;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
public class CalendarDemo {
public static void main(String[] args) {
String strDate = "2013-03-08";// 定义日期字符串
SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");// 定义日期格式
Date date = null;
try {
date = format.parse(strDate);// 将字符串转换为日期
} catch (ParseException e) {
System.out.println("输入的日期格式不合理！");
}
System.out.println(strDate + "是:" + getWeek(date));
System.out.println(strDate + "是一年的第:" + getWeekOfYear(date) + "周");
System.out.println(strDate + "是一年的" + (date.getMonth() + 1) + "月有:"
+ getDaysOfMonth(date.getYear(), date.getMonth() + 1) + "天");
System.out.println(strDate + "距离" + (format.format(new Date())) + "还有"
+ getDaysBetween(date, new Date()) + "天");
}
// 根据日期取得星期几
public static String getWeek(Date date) {
// String[] weeks = {"星期日","星期一","星期二","星期三","星期四","星期五","星期六"};
// Calendar cal = Calendar.getInstance();
// cal.setTime(date);
// int week_index = cal.get(Calendar.DAY_OF_WEEK) - 1;
// if(week_index<0){
// week_index = 0;
// }
// return weeks[week_index];
SimpleDateFormat sdf = new SimpleDateFormat("EEEE");
String week = sdf.format(date);
return week;
}
// 取得日期是某年的第几周
public static int getWeekOfYear(Date date) {
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int week_of_year = cal.get(Calendar.WEEK_OF_YEAR);
return week_of_year;
}
// 取得某个月有多少天
public static int getDaysOfMonth(int year, int month) {
Calendar cal = Calendar.getInstance();
cal.set(Calendar.YEAR, year);
cal.set(Calendar.MONTH, month-1);
int days_of_month = cal.getActualMaximum(Calendar.DAY_OF_MONTH);
return days_of_month;
}
// 取得两个日期之间的相差多少天
public static long getDaysBetween(Date date0, Date date1) {
long daysBetween = (date0.getTime() - date1.getTime() + 1000000) / 86400000;// 86400000=3600*24*1000 用立即数，减少乘法计算的开销
return daysBetween;
}
}
