1. Convert the timestamp to date format
@Test
public void test1(){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
// 获取当前系统时间戳
//long l = System.currentTimeMillis();
//如果你数据库存储的时间戳类型为string，就需要将string字符串转为long类型
String currentTime = "1602384121000";
long l = Long.parseLong(currentTime);
String format = sdf.format(l);
System.out.println("日期格式："+format);
//输出：日期格式：2020-10-11 10:42:01
}
2. Convert date format to timestamp
@Test
public void test2(){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String time = "2020-10-11 10:42:01";
Date date = null;
try {
date = sdf.parse(time);
} catch (ParseException e) {
e.printStackTrace();
}
long time1 = date.getTime();
System.out.println("时间戳格式："+time1);
//输出：时间戳格式：1602384121000
}
3. Time delay
@Test
public void test3(){
//创建Calendar实例
Calendar cal = Calendar.getInstance();
cal.setTime(new Date()); //设置当前时间
//推迟一天
//cal.add(Calendar.DATE, 1);
//推迟一个月
// cal.add(Calendar.MONTH, 1);
//时间推迟一年
cal.add(Calendar.YEAR,1);
long time = cal.getTime().getTime();
long time1 = new Date().getTime();
System.out.println("当前时间戳："+time1+"；推迟一年的时间戳："+time);
//输出：当前时间戳：1602501173582；推迟一年的时间戳：1634037173582
}
4.Date to String
@Test
public void test4(){
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date=new Date();
String format = sdf.format(date);
System.out.println("时间String："+format);
}
//输出：时间String：2020-10-12 19:12:36
5.String to date
@Test
public void test5(){
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String string = "2020-10-14 10:10:00";
Date date = null;
try{
date = sdf.parse(string);
}catch (Exception e){
e.printStackTrace();
}
System.out.println("Date:"+date);
//输出：Date:Wed Oct 14 10:10:00 CST 2020
}
6. Timestamp to date
@Test
public void dateToStamp() {
long times = 1602731137125L;
Date date = new Date(times);
System.out.println("date格式："+date);
//输出：date格式：Thu Oct 15 11:05:37 CST 2020
}
We often use timestamp/date format/string in projects, and the transition between them is shown above