【Java】这个案例帮你搞懂Date类型
如果你想了解Date类，就需要了解一些概念：
- 计算机没办法知道时间，所以把时间都表示成为了自1900年1月1日0时0分0秒0毫秒到现在的毫秒值。用龙来储存，这是基础。
- Date就是对计算机存储的毫秒值进行一个格式化，并展示。
- 在Date之上还有一个Calendar的封装，让Date操作更方便。
需求
一个公司有一个活动需要分批次发放红包，这个活动有开始时间（yyyy-MM-dd HH:mm:ss）和结束时间（yyyy-MM-dd HH:mm:ss），以及红包发放时间（HH:mm:ss）。从活动开始时间到结束时间，每到发放时间就会发放红包。请把发放机会以list的形式存储在RedPackage类中。
public class RedPackage {
//当日红包开始发放时间
private String startTime;
//当日红包结束发放时间
private String endTime;
}
public class DateTest {
private static String startTime = "2020-11-16 08:15:00";
private static String endTime = "2020-11-22 09:07:08";
private static String sendPerTime = "07:02:02";
public static void main(String[] args) {
List<RedPackage> redPackageList = convertTime(startTime, endTime, sendPerTime);
redPackageList.forEach(System.out::println);
}
}
实例
private static String startTime = "2020-11-16 08:15:00";
private static String endTime = "2020-11-22 09:07:08";
private static String sendPerTime = "07:02:02";
输出：
RedPackage(startTime=2020-11-17 07:02:02, endTime=2020-11-18 00:00:00)
RedPackage(startTime=2020-11-18 07:02:02, endTime=2020-11-19 00:00:00)
RedPackage(startTime=2020-11-19 07:02:02, endTime=2020-11-20 00:00:00)
RedPackage(startTime=2020-11-20 07:02:02, endTime=2020-11-21 00:00:00)
RedPackage(startTime=2020-11-21 07:02:02, endTime=2020-11-22 00:00:00)
RedPackage(startTime=2020-11-22 07:02:02, endTime=2020-11-22 09:07:08)
private static String startTime = "2020-11-16 08:15:00";
private static String endTime = "2020-11-22 09:07:08";
private static String sendPerTime = "10:02:02";
输出：
RedPackage(startTime=2020-11-16 10:02:02, endTime=2020-11-17 00:00:00)
RedPackage(startTime=2020-11-17 10:02:02, endTime=2020-11-18 00:00:00)
RedPackage(startTime=2020-11-18 10:02:02, endTime=2020-11-19 00:00:00)
RedPackage(startTime=2020-11-19 10:02:02, endTime=2020-11-20 00:00:00)
RedPackage(startTime=2020-11-20 10:02:02, endTime=2020-11-21 00:00:00)
RedPackage(startTime=2020-11-21 10:02:02, endTime=2020-11-22 00:00:00)
private static String startTime = "2020-11-16 08:15:00";
private static String endTime = "2020-11-22 19:07:08";
private static String sendPerTime = "10:02:02";
输出：
RedPackage(startTime=2020-11-16 10:02:02, endTime=2020-11-17 00:00:00)
RedPackage(startTime=2020-11-17 10:02:02, endTime=2020-11-18 00:00:00)
RedPackage(startTime=2020-11-18 10:02:02, endTime=2020-11-19 00:00:00)
RedPackage(startTime=2020-11-19 10:02:02, endTime=2020-11-20 00:00:00)
RedPackage(startTime=2020-11-20 10:02:02, endTime=2020-11-21 00:00:00)
RedPackage(startTime=2020-11-21 10:02:02, endTime=2020-11-22 00:00:00)
RedPackage(startTime=2020-11-22 10:02:02, endTime=2020-11-22 19:07:08)
解
package datetest;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Calendar;
import java.util.Date;
import java.util.List;
public class DateTest {
private static String startTime = "2020-11-16 08:15:00";
private static String endTime = "2020-11-22 09:07:08";
private static String sendPerTime = "07:02:02";
public static void main(String[] args) {
List<RedPackage> redPackageList = convertTime(startTime, endTime, sendPerTime);
redPackageList.forEach(System.out::println);
}
private static List<RedPackage> convertTime(String sourcesStartTime, String sourcesEndTime, String sourcesSendPerTime) {
List<RedPackage> redPackageList = new ArrayList<>();
SimpleDateFormat dateFormatWithDay = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
SimpleDateFormat dateFormatWithOutDay = new SimpleDateFormat("HH:mm:ss");
Date startTime = new Date();
Date endTime = new Date();
Date sendPerTime = new Date();
if ((sourcesStartTime == null || sourcesStartTime == "")
|| (sourcesEndTime == null || sourcesEndTime == "")
|| (sourcesSendPerTime == null || sourcesSendPerTime == "")) {
//报错
return null;
}
try {
startTime = dateFormatWithDay.parse(sourcesStartTime);
endTime = dateFormatWithDay.parse(sourcesEndTime);
sendPerTime = dateFormatWithOutDay.parse(sourcesSendPerTime);
} catch (ParseException e) {
e.printStackTrace();
}
//判断数据是否为空
if (startTime == null || endTime == null || sendPerTime == null) {
//报错
return null;
}
Calendar startTimeCalendar = Calendar.getInstance();
startTimeCalendar.setTime(startTime);
Calendar endTimeCalendar = Calendar.getInstance();
endTimeCalendar.setTime(endTime);
Calendar sendPerTimeCalendarWithoutYear = Calendar.getInstance();
sendPerTimeCalendarWithoutYear.setTime(sendPerTime);
Calendar sendPerTimeCalendar = buildDateWithYear(sendPerTimeCalendarWithoutYear, startTimeCalendar);
//开始时间晚于结束时间
if (startTimeCalendar.after(endTimeCalendar)) {
//报错
return null;
}
//开始时间和结束时间在一天
if (validateIsOneDay(startTimeCalendar, endTimeCalendar)) {
//放时间要晚于开始时间&&早于结束时间
if (sendPerTimeCalendar.after(endTimeCalendar) || sendPerTimeCalendar.before(startTimeCalendar)) {
//报错
return null;
} else {
//add sendPerTime - endTime
convertDateToRedPackage(redPackageList, startTimeCalendar, endTimeCalendar);
}
} else {
//开始时间和结束时间不在一天
//发放时间大于开始时间
if (sendPerTimeCalendar.after(startTimeCalendar)) {
//是 add sendPerTime - 24：00：00
Calendar startCalender = buildDateWithYear(sendPerTimeCalendar, startTimeCalendar);
Calendar endCalender = buildNextDayFirstTime(startTimeCalendar);
convertDateToRedPackage(redPackageList, startCalender, endCalender);
}else {
//下一天
buildNextDayFirstTime(startTimeCalendar);
buildDateWithYear(sendPerTimeCalendar, startTimeCalendar);
}
//是不是结束当天
//否 add sendPerTime - 24：00：00 循环
while (!validateIsOneDay(startTimeCalendar, endTimeCalendar)) {
Calendar startCalender = buildDateWithYear(sendPerTimeCalendar, startTimeCalendar);
Calendar endCalender = buildNextDayFirstTime(startTimeCalendar);
convertDateToRedPackage(redPackageList, startCalender, endCalender);
}
//是结束当天
Calendar startCalender = buildDateWithYear(sendPerTimeCalendar, startTimeCalendar);
//发放时间早于结束时间 add sendPerTime - endTime
if (startCalender.before(endTimeCalendar)) {
convertDateToRedPackage(redPackageList, startCalender, endTimeCalendar);
}
}
return redPackageList;
}
/**
* @param targetDateCalendar
* @return targetDateCalendar的下一天的00：00：00
*/
private static Calendar buildNextDayFirstTime(Calendar targetDateCalendar) {
int year = targetDateCalendar.get(Calendar.YEAR);
int month = targetDateCalendar.get(Calendar.MONTH);
int day = targetDateCalendar.get(Calendar.DAY_OF_MONTH);
targetDateCalendar.set(year, month, day + 1, 0, 0, 0);
return targetDateCalendar;
}
/**
* 因为传入的sendPerTime只有时分秒，在加入数据库中需要添加年月日
*
* @param targetDateCalendar 目标事件
* @param resourceDateCalendar 标记时间
* @return 将目标时间的年月日标记成标记时间返回
*/
private static Calendar buildDateWithYear(Calendar targetDateCalendar, Calendar resourceDateCalendar) {
targetDateCalendar.set(Calendar.YEAR, resourceDateCalendar.get(Calendar.YEAR));
targetDateCalendar.set(Calendar.MONTH, resourceDateCalendar.get(Calendar.MONTH));
targetDateCalendar.set(Calendar.DAY_OF_MONTH, resourceDateCalendar.get(Calendar.DAY_OF_MONTH));
return targetDateCalendar;
}
private static void convertDateToRedPackage(List<RedPackage> redPackageList, Calendar startTimeCalendar, Calendar endTimeCalendar) {
RedPackage redPackage = new RedPackage();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
redPackage.setStartTime(sdf.format(startTimeCalendar.getTime()));
redPackage.setEndTime(sdf.format(endTimeCalendar.getTime()));
redPackageList.add(redPackage);
}
/**
* 判断两个日期是否相同
*
* @param oneDateCalender
* @param anotherDateCalender
* @return
*/
private static Boolean validateIsOneDay(Calendar oneDateCalender, Calendar anotherDateCalender) {
int oneDateCalenderYear = oneDateCalender.get(Calendar.YEAR);
int oneDateCalenderMonth = oneDateCalender.get(Calendar.MONTH);
int oneDateCalenderDay = oneDateCalender.get(Calendar.DAY_OF_MONTH);
int anotherDateCalenderYear = anotherDateCalender.get(Calendar.YEAR);
int anotherDateCalenderMonth = anotherDateCalender.get(Calendar.MONTH);
int anotherDateCalenderDay = anotherDateCalender.get(Calendar.DAY_OF_MONTH);
if (oneDateCalenderYear == anotherDateCalenderYear
&& oneDateCalenderMonth == anotherDateCalenderMonth
&& oneDateCalenderDay == anotherDateCalenderDay) {
return true;
} else {
return false;
}
}
private static String convert(Calendar calendar) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
return sdf.format(calendar.getTime());
}
}
工具类
市面上有很多开源的工具类，非常的方便，虽然不提倡反复的造轮子，但是再造轮子的过程中，可以让自己提升，下面的链接时笔者自己开发的一个工具类，非常简单，也做了很多注释。希望可以帮到大家。
强大的开源Date工具类
