两个日期相差天数计算

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

public class Datesub {
   public static void main(String[] args) throws ParseException {
   SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
   Date d = sdf.parse("2007-03-01"); 
   Calendar calendar = Calendar.getInstance();
   calendar.setTime(new Date());
   long timethis = calendar.getTimeInMillis();
   calendar.setTime(d);
   long timeend = calendar.getTimeInMillis();
   long theday = (timeend - timethis) / (1000 * 60 * 60 * 24);
   System.out.print(theday);
 }

}

或

1. import java.text.ParseException;  
2. import java.text.SimpleDateFormat;  
3. import java.util.Calendar;  
4. import java.util.Date;  
5. 
   
6. public class test16 {  
7.     /** 
8.      * @param args 
9.      * @throws ParseException  
10.      */  
11.     public static void main(String[] args) throws ParseException {  
12.         // TODO Auto-generated method stub  
13.         SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");  
14.         Date d1=sdf.parse("2012-09-08 10:10:10");  
15.         Date d2=sdf.parse("2012-09-15 00:00:00");  
16.         System.out.println(daysBetween(d1,d2));  
17.   
18.         System.out.println(daysBetween("2012-09-08 10:10:10","2012-09-15 00:00:00"));  
19.     }  
20.       
21.     /**  
22.      * 计算两个日期之间相差的天数  
23.      * @param smdate 较小的时间 
24.      * @param bdate  较大的时间 
25.      * @return 相差天数 
26.      * @throws ParseException  
27.      */    
28.     public static int daysBetween(Date smdate,Date bdate) throws ParseException    
29.     {    
30.         SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");  
31.         smdate=sdf.parse(sdf.format(smdate));  
32.         bdate=sdf.parse(sdf.format(bdate));  
33.         Calendar cal = Calendar.getInstance();    
34.         cal.setTime(smdate);    
35.         long time1 = cal.getTimeInMillis();                 
36.         cal.setTime(bdate);    
37.         long time2 = cal.getTimeInMillis();         
38.         long between_days=(time2-time1)/(1000*3600*24);  
39.             
40.        return Integer.parseInt(String.valueOf(between_days));           
41.     }    
42.       
43. /** 
44. *字符串的日期格式的计算 
45. */  
46.    public static int daysBetween(String smdate,String bdate) throws ParseException{  
47.         SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");  
48.         Calendar cal = Calendar.getInstance();    
49.         cal.setTime(sdf.parse(smdate));    
50.         long time1 = cal.getTimeInMillis();                 
51.         cal.setTime(sdf.parse(bdate));    
52.         long time2 = cal.getTimeInMillis();         
53.         long between_days=(time2-time1)/(1000*3600*24);  
54.             
55.        return Integer.parseInt(String.valueOf(between_days));     
56.     }  
57.   
58. }