计算相隔日期天数工具类

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

public class DateUtil {
	/**
	* 读取两个日期之间的天数 
	* @param begin  yyyy-mm-dd
	* @param end  yyyymmdd
	* @return 
	*/  
	public static int getDays(String begin,String end) throws Exception{  
	        String strend=end.substring(0,4)+"-"+end.substring(4,6)+"-"+end.substring(6,8);  
	        int days=getBetweenDays(begin.toString(), strend);   
	        return days;  
	 }  
	      
	/**
	* 取得两个时间段的时间间隔  
	* return t2 与t1的间隔天数  
	* throws ParseException 如果输入的日期格式不是0000-00-00 格式抛出异常  
	*/   
	public static int getBetweenDays(String t1,String t2) throws ParseException{   
        DateFormat format = new SimpleDateFormat("yyyy-MM-dd");   
        int betweenDays = 0;   
        Date d1 = format.parse(t1);   
        Date d2 = format.parse(t2);   
        Calendar c1 = Calendar.getInstance();   
        Calendar c2 = Calendar.getInstance();   
        c1.setTime(d1);   
        c2.setTime(d2);   
        // 保证第二个时间一定大于第一个时间   
        if(c1.after(c2)){
            c1 = c2;   
            c2.setTime(d1);
            return betweenDays;
        }
        int betweenYears = c2.get(Calendar.YEAR)-c1.get(Calendar.YEAR);   
        betweenDays = c2.get(Calendar.DAY_OF_YEAR)-c1.get(Calendar.DAY_OF_YEAR);   
        for(int i=0;i