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java如何获取当前时间以及如何进行格式化?

 

起因:写代码的时候经常会用到获取当前时间戳和日期,现总结如下

public void testDate() {
//SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");//设置日期格式

Date date = new Date();
String dateString = date.toString();
long times = date.getTime();
System.out.println("date.toString():"+date.toString());
System.out.println("当前时间戳(毫秒):" + times);

Calendar c = Calendar.getInstance();
System.out.println("当前日期:" + c.get(Calendar.DATE));
System.out.println("当前年份:" + c.get(Calendar.YEAR));
//月份从0开始,0-11
System.out.println("当前月份:" + c.get(Calendar.MONTH));
//12小时制,0-11
System.out.println("12小时制:当前小时:" + c.get(Calendar.HOUR));
System.out.println("24小时制:当前小时:" + c.get(Calendar.HOUR_OF_DAY));
System.out.println("当前分钟:" + c.get(Calendar.MINUTE));
System.out.println("当前秒:" + c.get(Calendar.SECOND));
System.out.println("一年中的某天:" + c.get(Calendar.DAY_OF_YEAR));
System.out.println("当前时间戳(毫秒):" + c.getTimeInMillis());
System.out.println("Calendar的toString()方法一般用作调试:"+c.toString());
SimpleDateFormat df = new SimpleDateFormat("yyyyMMdd");
String currentDateStr = df.format(new Date());
System.out.println("当前日期yyyyMMdd:"+currentDateStr);

}


  

输出结果:

date.toString():Wed Aug 02 11:39:05 CST 2017
当前时间戳(毫秒):1501645145298
当前日期:2
当前年份:2017
当前月份:7
12小时制:当前小时:11
24小时制:当前小时:11
当前分钟:39
当前秒:5
一年中的某天:214
当前时间戳(毫秒):1501645145302
Calendar的toString()方法一般用作调试:java.util.GregorianCalendar[time=1501645145302,areFieldsSet=true,areAllFieldsSet=true,lenient=true,zone=sun.util.calendar.ZoneInfo[id="Asia/Shanghai",offset=28800000,dstSavings=0,useDaylight=false,transitions=19,lastRule=null],firstDayOfWeek=1,minimalDaysInFirstWeek=1,ERA=1,YEAR=2017,MONTH=7,WEEK_OF_YEAR=31,WEEK_OF_MONTH=1,DAY_OF_MONTH=2,DAY_OF_YEAR=214,DAY_OF_WEEK=4,DAY_OF_WEEK_IN_MONTH=1,AM_PM=0,HOUR=11,HOUR_OF_DAY=11,MINUTE=39,SECOND=5,MILLISECOND=302,ZONE_OFFSET=28800000,DST_OFFSET=0]
当前日期yyyyMMdd:20170802

java如何获取当前时间以及如何进行格式化?