java日期时间

获取时间戳

System.currentTimeMillis();
Calendar.getInstance().getTimeInMillis();
new Date().getTime();
#Java 8中的Instant类和Duration类
Instant now = Instant.now();
long timestamp = now.toEpochMilli();

获取unix时间戳

String dateStr = Long.toString(System.currentTimeMillis()/1000L);

通过Util包中的Date获取

https://blog.csdn.net/m0_67394360/article/details/123635483

#1.通过Util包中的Date获取
Date date = new Date();
SimpleDateFormat dateFormat= new SimpleDateFormat("yyyy-MM-dd :hh:mm:ss");
System.out.println(dateFormat.format(date));

#2.通过Util包的Calendar 获取
Calendar calendar= Calendar.getInstance();
SimpleDateFormat dateFormat= new SimpleDateFormat("yyyy-MM-dd :hh:mm:ss");
System.out.println(dateFormat.format(calendar.getTime()));

#3.通过Util包的Calendar 获取时间，分别获取年月日时分秒
Calendar cal=Calendar.getInstance();      
int y=cal.get(Calendar.YEAR);      
int m=cal.get(Calendar.MONTH);      
int d=cal.get(Calendar.DATE);      
int h=cal.get(Calendar.HOUR_OF_DAY);      
int mi=cal.get(Calendar.MINUTE);      
int s=cal.get(Calendar.SECOND);      
System.out.println("现在时刻是"+y+"年"+m+"月"+d+"日"+h+"时"+mi+"分"+s+"秒");