java Calendar Date 获取指定日期所在月或年的第一天和最后一天

一.获取传入日期所在月的第一天

    public static Date getFirstDayDateOfMonth(final Date date) {

        final Calendar cal = Calendar.getInstance();

        cal.setTime(date);

        final int last = cal.getActualMinimum(Calendar.DAY_OF_MONTH);

        cal.set(Calendar.DAY_OF_MONTH, last);

        return cal.getTime();

    }

二.获取传入日期所在月的最后一天

    public static Date getLastDayOfMonth(final Date date) {

        final Calendar cal = Calendar.getInstance();

        cal.setTime(date);

        final int last = cal.getActualMaximum(Calendar.DAY_OF_MONTH);

        cal.set(Calendar.DAY_OF_MONTH, last);

        return cal.getTime();

    }

三.获取传入日期所在年的第一天

    public static Date getFirstDayDateOfYear(final Date date) {

        final Calendar cal = Calendar.getInstance();

        cal.setTime(date);

        final int last = cal.getActualMinimum(Calendar.DAY_OF_YEAR);

        cal.set(Calendar.DAY_OF_YEAR, last);

        return cal.getTime();

    }

四.获取传入日期所在年的最后一天

    public static Date getLastDayOfYear(final Date date) {

        final Calendar cal = Calendar.getInstance();

        cal.setTime(date);

        final int last = cal.getActualMaximum(Calendar.DAY_OF_YEAR);

        cal.set(Calendar.DAY_OF_YEAR, last);

        return cal.getTime();

    }

五.获取指定年月的第一天

/**
      * 获取指定年月的第一天
      * @param year
      * @param month
      * @return
      */
     public static String getFirstDayOfMonth1(int year, int month) {
         Calendar cal = Calendar.getInstance();
         //设置年份
         cal.set(Calendar.YEAR, year);
         //设置月份
         cal.set(Calendar.MONTH, month-1);
         //获取某月最小天数
         int firstDay = cal.getMinimum(Calendar.DATE);
         //设置日历中月份的最小天数
         cal.set(Calendar.DAY_OF_MONTH,firstDay);
         //格式化日期
         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
         return sdf.format(cal.getTime());
     }

六.传入年和月，获取到本月的最后一天

/**
     * 获取指定年月的最后一天
     * @param year
     * @param month
     * @return
     */
     public static String getLastDayOfMonth1(int year, int month) {
         Calendar cal = Calendar.getInstance();
         //设置年份
         cal.set(Calendar.YEAR, year);
         //设置月份
         cal.set(Calendar.MONTH, month-1);
         //获取某月最大天数
         int lastDay = cal.getActualMaximum(Calendar.DATE);
         //设置日历中月份的最大天数
         cal.set(Calendar.DAY_OF_MONTH, lastDay);
         //格式化日期
         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
         return sdf.format(cal.getTime());
     }