java日期工具类Calendar

我会带着你远行 2022-03-25 15:48 380阅读 0赞

# 1，获取时间：年，月，日 时：分：秒 #

Calendar calendar = Calendar.getInstance();
    	int year = calendar.get(Calendar.YEAR);
    	int month = calendar.get(Calendar.MONTH);
    	int day_month = calendar.get(Calendar.DAY_OF_MONTH);
    	
    	int hour = calendar.get(Calendar.HOUR_OF_DAY);//15
    	int minute = calendar.get(Calendar.MINUTE);//16
    	int second = calendar.get(Calendar.SECOND);//9

# 2, 制作定时任务 #

linux自带的crontab -e命令

#每天23:00  定时关机
    #格式：分  时   天         月    周几           具体命令
    	  0   23   *          *     *             sudo  poweroff

java代码实现：

import java.util.Calendar;
    
    public class OntimeTest {
        public static void main(String[] args) {
            //间隔一段时间执行：   每隔1分钟： 打印时间戳
            intervalOnTime(0, 1, 0);
            //指定某个时间执行：   每天24:00:00执行计划
            fixedTimeAction(0, 0, 0);
        }
    
        private static void fixedTimeAction(int destHour, int destMinute, int destSecond) {
            while (true) {
                Calendar calendar = Calendar.getInstance();
            //        int year = calendar.get(Calendar.YEAR);
            //        int month = calendar.get(Calendar.MONTH);
            //        int day_month = calendar.get(Calendar.DAY_OF_MONTH);
    
                int hour = calendar.get(Calendar.HOUR_OF_DAY);//15
                int minute = calendar.get(Calendar.MINUTE);//16
                int second = calendar.get(Calendar.SECOND);//9
    
                if (hour == destHour && minute == destMinute && second == destSecond) {
                    System.out.println(hour + "," + minute + "," + second);
                }
            }
        }
    
        public static void intervalOnTime(int destHours, int destMinutes, int destSeconds) {
            Calendar calendar = Calendar.getInstance();
            int hour = calendar.get(Calendar.HOUR_OF_DAY);//15
            int minute = calendar.get(Calendar.MINUTE);//16
            int second = calendar.get(Calendar.SECOND);//9
    
            Calendar calendar2 = null;
            int hour2 = 0;
            int minute2 = 0;
            int second2 = 0;
    
            while (true) {
                calendar2 = Calendar.getInstance();
                hour2 = calendar2.get(Calendar.HOUR_OF_DAY);
                minute2 = calendar2.get(Calendar.MINUTE);
                second2 = calendar2.get(Calendar.SECOND);
    
                //计算时间差
                int hourDiff = hour2 - hour;
                int minuteDiff = minute2 - minute;
                int secondDiff = second2 - second;
    
                if (destHours != 0 && hourDiff == destHours //每小时： 轮询
                        && destMinutes == 0 && destSeconds == 0) {
                    System.out.println(hourDiff + " 小时过去了...");
                    hour = hour2;
                } else if (destMinutes != 0 && minuteDiff == destMinutes
                        && destHours == 0 && destSeconds == 0) {//每分钟： 轮询
                    System.out.println(minuteDiff + " 分钟过去了...");
                    minute = minute2;
                } else if (secondDiff != 0 && secondDiff == destSeconds
                        && destHours == 0 && destMinutes == 0) {//每秒钟： 轮询
                    System.out.println(secondDiff + " 秒过去了...");
                    second = second2;
                }
            }
        }
    }