java获取当前月第一天和最后一天

获取当前月第一天:

/**
     * 获取当前月第一天
     * @param month
     * @return
     */
    public static String getFirstDayOfMonth(int month) {
        Calendar calendar = Calendar.getInstance();
        // 设置月份
        calendar.set(Calendar.MONTH, month - 1);
        // 获取某月最小天数
        int firstDay = calendar.getActualMinimum(Calendar.DAY_OF_MONTH);
        // 设置日历中月份的最小天数
        calendar.set(Calendar.DAY_OF_MONTH, firstDay);
        // 格式化日期
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        String firstDay = sdf.format(calendar.getTime())+" 00:00:00";
        return firstDay;
    }

获取当前月最后一天:

public static String getLastDayOfMonth(int month) {
        Calendar calendar = Calendar.getInstance();
        // 设置月份
        calendar.set(Calendar.MONTH, month - 1);
        // 获取某月最大天数
        int lastDay=0;
        //2月的平年瑞年天数
        if(month==2) {
            lastDay = calendar.getLeastMaximum(Calendar.DAY_OF_MONTH);
        }else {
            lastDay = calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
        }
        // 设置日历中月份的最大天数
        calendar.set(Calendar.DAY_OF_MONTH, lastDay);
        // 格式化日期
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
        String lastDay = sdf.format(calendar.getTime())+" 23:59:59";
        return lastDay;
    }