Java Calendar详解 - 创建、获取、转换、日期加减

Java Calendar详解 - 创建、获取、转换、日期加减

创建

Java月份是从0-11，月份设置时要减1

// 使用当前时间创建
Calendar calendar = Calendar.getInstance();
// 设置指定日期，月份需要减一
calendar.set(year, month - 1, day);
// 指定时间创建，参数依次为：年，月，日，时，分，秒，月份需要减一
Calendar calendar = new GregorianCalendar(2016, 8, 1, 15, 41, 22);
// Date转换为Calendar 
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);

获取

获取年、月、日、时、分、秒、星期

Calendar calendar = Calendar.getInstance();
int year = calendar.get(Calendar.YEAR);
// 取月份要加1
int month = calendar.get(Calendar.MONTH) + 1;
int day = calendar.get(Calendar.DAY_OF_MONTH);
int hover = calendar.get(Calendar.HOUR_OF_DAY);
int minute = calendar.get(Calendar.MINUTE);
int seconds = calendar.get(Calendar.SECOND);
// 1-7分别代表 -- 星期日,星期一,星期二,星期三,星期四,星期五,星期六
int week = calendar.get(calendar.DAY_OF_WEEK);

获取当前月份的最大天数

Calendar.getInstance().getActualMaximum(Calendar.DAY_OF_MONTH);

操作

Calendar 转换为Date

Date date = Calendar.getInstance().getTime();

日期加减

public class TestCalendar {

    // 使用默认时区和语言环境获得一个日历。
    private static Calendar calendar = Calendar.getInstance()

    public static void print(String name) {

        System.out.print(name + ": ");

        System.out.println(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(calendar.getTime()));
    }

    public static void main(String[] args) {

        print("当前时间   ");

        calendar.add(Calendar.HOUR_OF_DAY, 1);

        print("增加1小时");
        calendar.add(Calendar.DAY_OF_MONTH, 1);
        print("增加1天    ");
        calendar.add(Calendar.MONTH, 1)

        print("增加1个月");
        calendar.add(Calendar.YEAR, 1);

        print("增加1年    ");

        calendar.add(Calendar.YEAR, -2);

        print("减少2年    ");

    }

}

两个日期相差天数

long millisOfDay = 24 * 60 * 60 * 1000;

Calendar calendar = new GregorianCalendar(2015, 9, 1);

Calendar calendar1 = new GregorianCalendar(2016, 9, 1);

Calendar calendar2 = new GregorianCalendar(2017, 9, 1);

// 2016年是闰年，得到366天

System.out.println((calendar1.getTimeInMillis() - calendar.getTimeInMillis()) / millisOfDay);


// 2017年是平年，得到365天

System.out.println((calendar2.getTimeInMillis() - calendar1.getTimeInMillis()) / millisOfDay);

Calendar获取年、月、日、时间

Calendar c = Calendar.getInstance(TimeZone.getTimeZone("GMT+08:00"));    //获取东八区时间
        //获取年
        int year = c.get(Calendar.YEAR);
        //获取月份，0表示1月份
        int month = c.get(Calendar.MONTH) + 1;
        //获取当前天数
        int day = c.get(Calendar.DAY_OF_MONTH);
        //获取本月最小天数
        int first = c.getActualMinimum(Calendar.DAY_OF_MONTH);
        //获取本月最大天数
        int last = c.getActualMaximum(Calendar.DAY_OF_MONTH);
        //获取当前小时
        int time = c.get(Calendar.HOUR_OF_DAY);
        //获取当前分
        int min = c.get(Calendar.MINUTE);
        //获取当前
        int sec = c.get(Calendar.SECOND);                                                     
        SimpleDateFormat s = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String curDate = s.format(c.getTime());             //当前日期
        System.out.println("当前时间：" + year + "-" + month + "-" + day + " " + time + ":" + min + ":" + sec);
        System.out.println("第一天和最后天：" + first +"," + last);
        System.out.println("当前日期：" + curDate);