时间相关

1 计算过去某个时间距离当前的天数

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

public class Utils {

	/**
	 * 计算发布日期距离当前日期的天数，精确到天，时、分、秒、毫秒都清零
	 * @param publishTime
	 * @return
	 * @throws ParseException
	 */
	public static long getPublishedDays(String publishTime) throws ParseException{
		long dayDiff=0;
		SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	
		Date p = format.parse(publishTime);
		Calendar c1 = Calendar.getInstance();

		c1.set(Calendar.HOUR_OF_DAY, 0);
		c1.set(Calendar.MINUTE, 0);
		c1.set(Calendar.SECOND, 0);
		c1.set(Calendar.MILLISECOND, 0);
		
		Calendar c2 = Calendar.getInstance();
		c1.setTime(p);
		c1.set(Calendar.HOUR_OF_DAY, 0);
		c1.set(Calendar.MINUTE, 0);
		c1.set(Calendar.SECOND, 0);
		c1.set(Calendar.MILLISECOND, 0);
		
		dayDiff=(c2.getTimeInMillis()-c1.getTimeInMillis())/(1000*60*60*24);
		
		return dayDiff;
	}
}