计算日期的时间差

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Main {

	/**
	 * @param args
	 * @throws ParseException
	 */
	public static void main(String[] args) throws ParseException {
		// TODO Auto-generated method stub
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		Date d1 = sdf.parse("2012-09-08 10:10:10");
		Date d2 = sdf.parse("2012-09-15 00:00:00");
		System.out.println(daysBetween(d1, d2));

		System.out.println(daysBetween("2012-09-08 10:10:10",
				"2012-09-15 00:00:00"));
		dateDiff("2012-09-08 00:00:00", "2012-09-08 01:00:00", "yyyy-MM-dd HH:mm:ss");
		
		SimpleDateFormat format=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
		String nowTime=format.format(new Date());
		System.out.println(nowTime);
		
		System.out.println(24*60*60*1000);

	}

	/**
	 * 计算两个日期之间相差的天数
	 * 
	 * @param smdate
	 *            较小的时间
	 * @param bdate
	 *            较大的时间
	 * @return 相差天数
	 * @throws ParseException
	 */
	public static int daysBetween(Date smdate, Date bdate)
			throws ParseException {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		smdate = sdf.parse(sdf.format(smdate));
		bdate = sdf.parse(sdf.format(bdate));
		Calendar cal = Calendar.getInstance();
		cal.setTime(smdate);
		long time1 = cal.getTimeInMillis();
		cal.setTime(bdate);
		long time2 = cal.getTimeInMillis();
		long between_days = (time2 - time1) / (1000 * 3600 * 24);

		return Integer.parseInt(String.valueOf(between_days));
	}

	/**
	 * 字符串的日期格式的计算
	 */
	public static int daysBetween(String smdate, String bdate)
			throws ParseException {
		SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
		Calendar cal = Calendar.getInstance();
		cal.setTime(sdf.parse(smdate));
		long time1 = cal.getTimeInMillis();
		cal.setTime(sdf.parse(bdate));
		long time2 = cal.getTimeInMillis();
		long between_days = (time2 - time1) / (1000 * 3600 * 24);

		return Integer.parseInt(String.valueOf(between_days));
	}
	
	public static void dateDiff(String startTime, String endTime, String format) {
		//按照传入的格式生成一个simpledateformate对象
		SimpleDateFormat sd = new SimpleDateFormat(format);
		long nd = 1000*24*60*60;//一天的毫秒数
		long nh = 1000*60*60;//一小时的毫秒数
		long nm = 1000*60;//一分钟的毫秒数
		long ns = 1000;//一秒钟的毫秒数long diff;try {
		//获得两个时间的毫秒时间差异
		long diff = 0;
		try {
			diff = sd.parse(endTime).getTime() - sd.parse(startTime).getTime();
		} catch (ParseException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		long day = diff/nd;//计算差多少天
		long hour = diff%nd/nh;//计算差多少小时
		long min = diff%nd%nh/nm;//计算差多少分钟
		long sec = diff%nd%nh%nm/ns;//计算差多少秒//输出结果
		long second = diff/ns;
		System.out.println("时间相差："+day+"天"+hour+"小时"+min+"分钟"+sec+"秒。");
		System.out.println(second);
	}

}