如何获取本星期的起止时间

Question

/**
   * 方法说明：
   *   得到给定日期（Calendar格式）所在星期的日期值<p>
   *   @param   cal Calendar:给定的日期
   *   @exception SQLException 当某一特定情况出现时，抛出此异常
   *   @since 1.0.0
   */  public static Collection dayInWeek(Calendar cal)
  {
    Vector vec=new Vector();
    String dayinweek=null;
    Debug.print("Tools--dayInWeek:");
    try
    {
      int days=cal.get(cal.DAY_OF_WEEK)-1;
      int dates=cal.get(cal.DAY_OF_MONTH);
      int months=cal.get(cal.MONTH);
      int years=cal.get(cal.YEAR);
      for(int i=0;i<7;i++)
      {
        cal.set(years,months,dates-days+i);
        dayinweek=dateToString(cal);
        vec.addElement(dayinweek);
        dayinweek=null;
      }
    }
    catch(Exception ex)
    {
    Debug.print("Tools--dayInWeek:"+ex.toString());
    }
    return vec;
  }