Java 毫秒级时间戳与日期相互转化

import java.text.ParseException;
import java.text.SimpleDateFormat;

public class Main2 {
	static String df1="yyyy-MM-dd HH:mm:ss";
	public static void main(String[] args) {
		try {
			System.out.println(timstamp2DateTime(1569289484000l));
			System.out.println(DateTime2timstamp("2019-09-24 09:44:44"));
		} catch(ParseException e) {
			e.printStackTrace();
		}
	}
	
	/**
	 * 毫秒级时间戳转化成日期和时间
	 * 
	 * @param trackTime
	 * @return
	 */
	public static String timstamp2DateTime(Long timestamp) {
		return new SimpleDateFormat(df1).format(timestamp);
	}
	
	public static Long DateTime2timstamp(String dateTime) throws ParseException {
		return (new SimpleDateFormat(df1)).parse(dateTime).getTime();
	}
}