Java获取当前时间戳

Timestamp timestamp = new Timestamp(System.currentTimeMillis());
//2016-11-16 06:43:19.77

package com.mkyong.date;
 
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Date;
public class TimeStampExample {
    private static final SimpleDateFormat sdf = new SimpleDateFormat("yyyy.MM.dd.HH.mm.ss");
    public static void main(String[] args) {
        //method 1
        Timestamp timestamp = new Timestamp(System.currentTimeMillis());
        System.out.println(timestamp);
        //method 2 - via Date
        Date date = new Date();
        System.out.println(new Timestamp(date.getTime()));
        //return number of milliseconds since January 1, 1970, 00:00:00 GMT
        System.out.println(timestamp.getTime());
        //format timestamp
        System.out.println(sdf.format(timestamp));
        
    }
}

package com.mkyong.date;
 
import java.sql.Timestamp;
import java.time.Instant;
public class InstantExample {
    
    public static void main(String[] args) {
        Timestamp timestamp = new Timestamp(System.currentTimeMillis());
        System.out.println(timestamp);
        //return number of milliseconds since January 1, 1970, 00:00:00 GMT
        System.out.println(timestamp.getTime());
        // Convert timestamp to instant
        Instant instant = timestamp.toInstant();
        System.out.println(instant);
        //return number of milliseconds since the epoch of 1970-01-01T00:00:00Z
        System.out.println(instant.toEpochMilli());
        // Convert instant to timestamp
        Timestamp tsFromInstant = Timestamp.from(instant);
        System.out.println(tsFromInstant.getTime());
    }
}

//方法 一
System.currentTimeMillis();
//方法 二
Calendar.getInstance().getTimeInMillis();
//方法 三
new Date().getTime();

SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式
String date = df.format(new Date());// new Date()为获取当前系统时间，也可使用当前时间戳

import java.util.Calendar;
import java.util.Date;
 
public class TimeTest {
    private static long _TEN_THOUSAND=10000;
    public static void main(String[] args) {
        long times=1000*_TEN_THOUSAND;
        long t1=System.currentTimeMillis();
        testSystem(times);
        long t2=System.currentTimeMillis();
        System.out.println(t2-t1);
        testCalander(times);
        long t3=System.currentTimeMillis();
        System.out.println(t3-t2);
        testDate(times);
        long t4=System.currentTimeMillis();
        System.out.println(t4-t3);
    }
    public static void testSystem(long times){//use 188
        for(int i=0;i<times;i++){
            long currentTime=System.currentTimeMillis();
        }
    public static void testCalander(long times){//use 6299
            long currentTime=Calendar.getInstance().getTimeInMillis();
    public static void testDate(long times){
            long currentTime=new Date().getTime();
}