System.currentTimeMillis()计算方式与时间的单位转换详解

    //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);
  }
}