计算两个日期之间有多少天多少小时多少分钟

package date;

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

public class CalculateIntervalBetween2Dates {
    private static final long DAY=24*60*60*1000;
    private static final long HOUR=60*60*1000;
    private static final long MINUTES=60*1000;
    private static final long SECONDS=1000;
    private static final long MILLIONSECONDS=1;
    
    public static void main(String[] args) {
	String startDateStr = "20121022";
	String endDateStr = "20121206";
	CalculateIntervalBetween2Dates.listNumberOfDates(startDateStr, endDateStr);
	CalculateIntervalBetween2Dates.calculateInterval(startDateStr, endDateStr,MILLIONSECONDS);
	CalculateIntervalBetween2Dates.calculateInterval(startDateStr, endDateStr,SECONDS);
	CalculateIntervalBetween2Dates.calculateInterval(startDateStr, endDateStr,MINUTES);
	CalculateIntervalBetween2Dates.calculateInterval(startDateStr, endDateStr,HOUR);
	CalculateIntervalBetween2Dates.calculateInterval(startDateStr, endDateStr,DAY);
    }
    
    /**
     * List dates between start date and end date, including the start date and end date.
     * @param startDateStr
     * @param endDateStr
     */
    public static void listNumberOfDates(String startDateStr,String endDateStr){
	SimpleDateFormat sf = new SimpleDateFormat("yyyyMMdd");
	Date startDate = null;
	Date endDate = null;
	try {
	    startDate = sf.parse(startDateStr);
	    endDate = sf.parse(endDateStr);
	} catch (ParseException e) {
	    e.printStackTrace();
	}
	Calendar c1 = Calendar.getInstance();
	List<Date> cancelDates = new ArrayList<Date>();
	if (startDate != null && endDate != null && startDate.before(endDate)) {
	    Date tempDate = startDate;
	    do {
		cancelDates.add(tempDate);
		c1.setTime(tempDate);
		c1.add(Calendar.DAY_OF_MONTH, 1);
		tempDate = c1.getTime();
	    } while (tempDate.before(endDate));
	    cancelDates.add(endDate);
	}
	
	System.out.println("There are " + cancelDates.size() + " days between " + sf.format(startDate) + " and " + sf.format(endDate) + ", inclusive.");
	System.out.println("See the following list:");
	for (Date date : cancelDates) {
	    System.out.println(sf.format(date));
	}
	System.out.println();
    }
    
    /**
     * Calculate how many days/hours/minutes/seconds/million seconds between start date and end date, including the start date and end date.
     * @param startDateStr
     * @param endDateStr
     * @param interval
     */
    public static void calculateInterval(String startDateStr,String endDateStr,long interval){
	SimpleDateFormat sf = new SimpleDateFormat("yyyyMMdd");
	Date startDate = null;
	Date endDate = null;
	try {
	    startDate = sf.parse(startDateStr);
	    endDate = sf.parse(endDateStr);
	} catch (ParseException e) {
	    e.printStackTrace();
	}
	Calendar c1 = Calendar.getInstance();
	c1.setTime(startDate);
	long startInMillis=c1.getTimeInMillis();
	c1.setTime(endDate);
	//inclusive,2009/10/24-2009/10/23=1,but actually 2 days
	c1.add(Calendar.DAY_OF_MONTH, 1);
	
	long endInMillis=c1.getTimeInMillis();
	long between=endInMillis-startInMillis;
	System.out.println("There are " + (between/interval) +" "+getIntervalLabel(interval) + " between " + sf.format(startDate) + " and " + sf.format(endDate) + ", inclusive");
    }
    
    private static String getIntervalLabel(long interval){
	if(interval==DAY){
	    return "days";
	}else if(interval==HOUR){
	    return "hours";
	}else if(interval==MINUTES){
	    return "minutes";
	}else if(interval==SECONDS){
	    return "seconds";
	}else if(interval==MILLIONSECONDS){
	    return "million seconds";
	}else{
	    return "error";
	}
    }
}