java 時間操做

記錄一些時間經常使用操做

public class DateCa {
    
    public static void main(String[] args) throws ParseException {
        
        /** 時間操做首推Calendar 格里高利曆 **/
        Calendar ca =  Calendar.getInstance();
        //獲取日期的單個屬性:年,月,周,日,時,分
        System.out.println(ca.get(Calendar.YEAR));
        System.out.println(ca.get(Calendar.MONTH));//獲取月份從0開始
        System.out.println(ca.get(Calendar.WEEK_OF_YEAR));
        System.out.println(ca.get(Calendar.DAY_OF_MONTH));
        System.out.println(ca.get(Calendar.HOUR_OF_DAY));
        System.out.println(ca.get(Calendar.MINUTE));

        //日期操做
        ca.add(Calendar.YEAR, 2);//退後兩年
        System.out.println(ca.get(Calendar.YEAR));
        ca.add(Calendar.MONTH, 2);//退後兩月
        System.out.println(ca.get(Calendar.MONTH));
        ca.add(Calendar.DAY_OF_MONTH, 10);//退後兩天
        System.out.println(ca.get(Calendar.DAY_OF_MONTH));
        
        //直接設置所需時間
        ca.set(Calendar.YEAR,100);//將給定的日曆字段設置爲給定值。
        System.out.println(ca.get(Calendar.YEAR));
        ca.set(2018, 7, 12);
        System.out.println(ca.get(Calendar.YEAR));
        System.out.println(ca.get(Calendar.MONTH));
        System.out.println(ca.get(Calendar.DAY_OF_MONTH));
        
        //時間比較推薦
        System.out.println(ca.after(new Date()));
        System.out.println(ca.before(new Date()));

        //也能夠獲取指定時區的時間系統
        System.out.println(Calendar.getInstance(Locale.ENGLISH));
        
        /** 其餘時間操做**/
        //當前秒數
        System.out.println(System.currentTimeMillis());
        System.out.println(new Date().getTime());
        //時間格式化
        SimpleDateFormat sf = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
        System.out.println(sf.format(ca.getTime()));
        System.out.println(sf.parse("2018-10-12 09:18:23").after(new Date()));
    }
}