java通过年月获取当前月所有周（跨月），获取每周开始日期和结束日期
/*** 根据年月返回本月共几周，每周开始与结束日期*/public static List<Map<String, String>> queryWeek(String year, String month) throws ParseException {/** 周 **/final String[] weeks = { "第一周", "第二周", "第三周", "第四周", "第五周", "第六周" };Calendar calendar = Calendar.getInstance();SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");try {calendar.setTime(sdf.parse(year + "-" + month + "-01"));} catch (ParseException e) {e.printStackTrace();}int i = calendar.get(Calendar.DAY_OF_WEEK);int months = calendar.get(Calendar.MONTH);switch (i) {case 1:calendar.add(Calendar.DATE, 1);break;case 2:calendar.add(Calendar.DATE, 0);break;case 3:calendar.add(Calendar.DATE, 6);break;case 4:calendar.add(Calendar.DATE, 5);break;case 5:calendar.add(Calendar.DATE, 4);break;case 6:calendar.add(Calendar.DATE, 3);break;case 7:calendar.add(Calendar.DATE, 2);break;default:break;}// 本月的第一个星期List<Map<String, String>> list = new ArrayList<Map<String, String>>();int index = 0;while (true) {if (index++ > 0){calendar.add(Calendar.DATE, 1);}Map<String, String> map = new HashMap<String, String>();map.put("start", sdf.format(calendar.getTime()));calendar.add(Calendar.DATE, 6);map.put("end", sdf.format(calendar.getTime()));map.put("week", weeks[index - 1]);list.add(map);// 判断是否跨月if (months != calendar.get(Calendar.MONTH)){break;}}return list;}测试：public static void main(String[] args) throws Exception {List<Map<String, String>> list = queryWeek("2023","10");System.out.println(list);}打印结果：
[
{ week=第一周, start=2023-10-02, end=2023-10-08 },
{ week=第二周, start=2023-10-09, end=2023-10-15 },
{ week=第三周, start=2023-10-16, end=2023-10-22 },
{ week=第四周, start=2023-10-23, end=2023-10-29 },
{ week=第五周, start=2023-10-30, end=2023-11-05 }
]