Java中System.currentTimeMillis()计算方式与时间单位转换讲解

        //获得系统的时间，单位为毫秒,转换为妙
        long totalMilliSeconds = System.currentTimeMillis();
        long totalSeconds = totalMilliSeconds / 1000;
         
        //求出现在的秒
        long currentSecond = totalSeconds % 60;
         
        //求出现在的分
        long totalMinutes = totalSeconds / 60;
        long currentMinute = totalMinutes % 60;
         
        //求出现在的小时
        long totalHour = totalMinutes / 60;
        long currentHour = totalHour % 24;
         
        //显示时间
        System.out.println("总毫秒为： " + totalMilliSeconds);
        System.out.println(currentHour + ":" + currentMinute + ":" + currentSecond + " GMT");

package demo.spli;

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.TimeZone;


public class ShowCurrentTime {

    /**
     * @显示当前时间
     * @2014.9.3
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //获得系统的时间，单位为毫秒,转换为妙
        long totalMilliSeconds = System.currentTimeMillis();
        
        DateFormat dateFormatterChina = DateFormat.getDateTimeInstance(DateFormat.MEDIUM,DateFormat.MEDIUM);//格式化输出
        TimeZone timeZoneChina = TimeZone.getTimeZone("Asia/Shanghai");//获取时区 这句加上，很关键。
        dateFormatterChina.setTimeZone(timeZoneChina);//设置系统时区
        long totalSeconds = totalMilliSeconds / 1000;
        
        //求出现在的秒
        long currentSecond = totalSeconds % 60;
        
        //求出现在的分
        long totalMinutes = totalSeconds / 60;
        long currentMinute = totalMinutes % 60;
        
        //求出现在的小时
        long totalHour = totalMinutes / 60;
        long currentHour = totalHour % 24;
        
        //显示时间
        System.out.println("总毫秒为： " + totalMilliSeconds);
        System.out.println(currentHour + ":" + currentMinute + ":" + currentSecond + " GMT");
        
        
        Date nowTime = new Date(System.currentTimeMillis());
        System.out.println(System.currentTimeMillis());
        SimpleDateFormat sdFormatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:dd");
        String retStrFormatNowDate = sdFormatter.format(nowTime);
          
        System.out.println(retStrFormatNowDate);
    }

}