java中的Date和Calendar相关方法

蔚落 2022-05-24 10:51 196阅读 0赞

在开发中有一些需求和Date和Calendar有关，所以在这里总结一下这些实现，以后可以直接使用：  
1.获取指定日期是星期几， 参数为null时表示获取当前日期是星期几

public static String getWeekOfDate(Date date) {
            String[] weekOfDays = {"星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六"};
            Calendar calendar = Calendar.getInstance();
            if (date != null) {
                calendar.setTime(date);
            }
            int w = calendar.get(Calendar.DAY_OF_WEEK) - 1;
            if (w < 0) {
                w = 0;
            }
            return weekOfDays[w];
        }

2.获取本月的第一天（或者当前日期）

public static String currDate(String current) {
            String currdate = "";
            Calendar cal = Calendar.getInstance();
            cal.setTime(new Date());
            if ("1".equals(current)) {    //current=1:表示获取本月的第一天，否则获取当前日期
                cal.set(Calendar.DAY_OF_MONTH, 1);
            }
            currdate = new SimpleDateFormat("yyyy-MM").format(cal.getTime());
            return currdate;
        }

3.查询上个月（上上个月。。。)的第一天和最后一天

public static String findLastMonth(int num) {
            SimpleDateFormat df = new SimpleDateFormat("yyyy-MM");
    
            Calendar cal = Calendar.getInstance();
            GregorianCalendar gcLast = (GregorianCalendar) Calendar.getInstance();
            Calendar calendar = Calendar.getInstance();
            calendar.setTime(new Date());
    
            calendar.add(Calendar.MONTH, num);   //-1：表示上个月  -2：表示上上个月
            Date theDate = calendar.getTime();
            gcLast.setTime(theDate);
            gcLast.set(Calendar.DAY_OF_MONTH, 1);
            String day_first_prevM = df.format(gcLast.getTime());
            StringBuffer str = new StringBuffer().append(day_first_prevM);
            day_first_prevM = str.toString();
            return day_first_prevM;
        }

4.查询当前日期前(后)x天的日期

public static String beforNumberDay(Date date, int day) {
            Calendar c = Calendar.getInstance();
            c.setTime(date);
            c.add(Calendar.DAY_OF_YEAR, day);
            return new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());
        }

5.获取某年度的最后一天

public static String getYearLastDate(int year, String pattern) {
            Calendar calendar = Calendar.getInstance();
            calendar.clear();
            calendar.set(Calendar.YEAR, year);
            calendar.roll(Calendar.DAY_OF_YEAR, -1);
            Date currYearLast = calendar.getTime();
            return DateFormatUtils.format(currYearLast, pattern);
        }

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