获取某周前的礼拜一

package com.poi.examples;  
  
import java.text.SimpleDateFormat;  
import java.util.*;  
  
public class PrevWeek {  
     public static void main(String[] args) {  
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");  
            Date dt = prevWeek(new Date(), 7);  
            System.out.println(sdf.format(dt));  
        }  
       
        public static Date prevWeek(Date dt, int week) {  
            Calendar cal = Calendar.getInstance();  
            cal.setTime(dt);  
            cal.add(Calendar.DAY_OF_MONTH, -week * 7 + (9-cal.get(Calendar.DAY_OF_WEEK)));  
            return cal.getTime();  
        }  
}