java根据日期获得星期常用方法

 /** 
     * 根据日期获得星期 
     * @param date 
     * @return 
     */ 
public static String getWeekOfDate(Date date) { 
  String[] weekDaysName = { "星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六" }; 
  String[] weekDaysCode = { "0", "1", "2", "3", "4", "5", "6" }; 
  Calendar calendar = Calendar.getInstance(); 
  calendar.setTime(date); 
  int intWeek = calendar.get(Calendar.DAY_OF_WEEK) - 1; 
  return weekDaysCode[intWeek]; 
} 
/** 
  * 获得周一的日期 
  * 
  * @param date 
  * @return 
  */ 
public static String getMonday(Date date) {

  Calendar calendar = Calendar.getInstance();

  calendar.setTime(date);

  calendar.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);

  return dateFormat.format(calendar.getTime());

} 
/** 
  * 获得周三的日期 
  * 
  * @param date 
  * @return 
  */ 
public static String getWednesday(Date date) {

  Calendar calendar = Calendar.getInstance();

  calendar.setTime(date);

  calendar.set(Calendar.DAY_OF_WEEK, Calendar.WEDNESDAY);

  return dateFormat.format(calendar.getTime());

} 
    /** 
  * 获得周五的日期 
  * 
  * @param date 
  * @return 
  */ 
public static String getFriday(Date date) {

  Calendar calendar = Calendar.getInstance();

  calendar.setTime(date);

  calendar.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);

  return dateFormat.format(calendar.getTime()); 
}

/** 
  * 当前日期前几天或者后几天的日期 
  * @param n 
  * @return 
  */  
public static String afterNDay(int n) {

  Calendar calendar = Calendar.getInstance();

  calendar.setTime(new Date());

  calendar.add(Calendar.DATE, n);

  Date date = calendar.getTime();

  String s = dateFormat.format(date);

  return s;

} 
/** 
  * 判断两个日期是否在同一周 
  * 
  * @param date1 
  * @param date2 
  * @return 
  */ 
public static boolean isSameWeekDates(Date date1, Date date2) { 
  Calendar cal1 = Calendar.getInstance(); 
  Calendar cal2 = Calendar.getInstance(); 
  cal1.setTime(date1); 
  cal2.setTime(date2); 
  int subYear = cal1.get(Calendar.YEAR) - cal2.get(Calendar.YEAR); 
  if (0 == subYear) { 
   if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2 
     .get(Calendar.WEEK_OF_YEAR)) 
    return true; 
  } else if (1 == subYear && 11 == cal2.get(Calendar.MONTH)) { 
   // 如果12月的最后一周横跨来年第一周的话则最后一周即算做来年的第一周 
   if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2 
     .get(Calendar.WEEK_OF_YEAR)) 
    return true; 
  } else if (-1 == subYear && 11 == cal1.get(Calendar.MONTH)) { 
   if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2 
     .get(Calendar.WEEK_OF_YEAR)) 
    return true; 
  } 
  return false; 
}