判斷一個時間段內有多少個週末

/**判斷某段日期內一共有幾天*/
import java.util.*;
import java.io.*;

public class DaysOf {

 /**
  * @param args
  */
 public static void main(String[] args) {
  // TODO Auto-generated method stub
  Calendar start = new GregorianCalendar(2009,0,1,0,0);
  Calendar end = new GregorianCalendar(2009,11,12,0,0);
  long day = 86400000;//一天的millis
  long mod =(end.getTimeInMillis()-start.getTimeInMillis())/day;
  System.out.println("一共是"+mod+"天");
  int n = start.get(Calendar.DAY_OF_WEEK);//2009-1-1是周幾
  //週日到週六分別是1~7
  long cnt = mod/7;//幾個整週
  cnt=cnt*2;
  long yushu = mod%7;
  
  if(n+yushu>7)
   cnt=cnt+2;//過了週六
  if(n+yushu==7)
   cnt++;//正好是週六
  System.out.println("不算週六週日共"+(mod-cnt)+"天");
 }

}