计算当前日期是一年中的第几周

    public static void main(String[] args) {
        Calendar gc = Calendar.getInstance();
        int week=gc.get(Calendar.WEEK_OF_YEAR);//返回一年中的第几周
        System.out.print(week);
    }

计算包含日期的周

    public static void main(String[] args) {
        SimpleDateFormat format = new java.text.SimpleDateFormat("yyyyMMdd");
        Calendar gc = Calendar.getInstance();
        String t = format.format(gc.getTime());
        String t1 = String.valueOf(gc.get(Calendar.WEEK_OF_YEAR));
        String val = t +" 第"+ t1+"周";
        System.out.println(val);
        String sub= val.substring(0, 4)+val.substring(10, 12);
        System.out.println(sub);
    }