1、字符串转日期
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String str = "2019-09-16 09:40:19";
//字符串转日期
Date date = sdf.parse(str);
System.out.println("print: "+ date);

2、日期转字符串
String strNew = sdf.format(date);
System.out.println("strNew"+strNew);

3、日期转时间戳
long time = date.getTime();
System.out.println("time"+time);

4、时间戳转日期
Date dateNew = new Date(time);
System.out.println("dateNew"+dateNew);
