本文目录导读：
我来为您提供Java日期时间处理的实操案例,涵盖常用场景。
基础日期时间操作
获取当前日期时间
import java.time.LocalDate;
import java.time.LocalTime;
import java.time.LocalDateTime;
public class DateTimeBasicDemo {
public static void main(String[] args) {
// 获取当前日期
LocalDate today = LocalDate.now();
System.out.println("当前日期: " + today); // 2024-01-15
// 获取当前时间
LocalTime now = LocalTime.now();
System.out.println("当前时间: " + now); // 14:30:25.123
// 获取当前日期时间
LocalDateTime dateTimeNow = LocalDateTime.now();
System.out.println("当前日期时间: " + dateTimeNow);
}
}
日期格式化与解析
import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;
public class DateTimeFormatDemo {
public static void main(String[] args) {
// 定义日期时间字符串
String dateStr = "2024-01-15 14:30:00";
// 创建格式化器
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
// 解析字符串为LocalDateTime
LocalDateTime dateTime = LocalDateTime.parse(dateStr, formatter);
System.out.println("解析后的时间: " + dateTime);
// 格式化LocalDateTime为字符串
String formattedDate = dateTime.format(DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH时mm分ss秒"));
System.out.println("格式化结果: " + formattedDate);
// 其他常用格式
DateTimeFormatter[] formatters = {
DateTimeFormatter.ISO_DATE,
DateTimeFormatter.ISO_DATE_TIME,
DateTimeFormatter.ofPattern("yyyy/MM/dd"),
DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm")
};
for (DateTimeFormatter fmt : formatters) {
System.out.println(dateTime.format(fmt));
}
}
}
日期计算与操作
import java.time.LocalDate;
import java.time.LocalDateTime;
import java.time.Period;
import java.time.temporal.ChronoUnit;
public class DateTimeCalculationDemo {
public static void main(String[] args) {
LocalDate today = LocalDate.now();
// 加减天、月、年
LocalDate nextWeek = today.plusDays(7);
LocalDate nextMonth = today.plusMonths(1);
LocalDate lastYear = today.minusYears(1);
System.out.println(" " + today);
System.out.println("一周后: " + nextWeek);
System.out.println("一个月后: " + nextMonth);
System.out.println("一年前: " + lastYear);
// 计算两个日期之间的差值
LocalDate start = LocalDate.of(2024, 1, 1);
LocalDate end = LocalDate.of(2024, 12, 31);
long daysBetween = ChronoUnit.DAYS.between(start, end);
long monthsBetween = ChronoUnit.MONTHS.between(start, end);
System.out.println("相差天数: " + daysBetween);
System.out.println("相差月数: " + monthsBetween);
// 使用Period计算
Period period = Period.between(start, end);
System.out.println("相差: " + period.getYears() + "年" +
period.getMonths() + "月" +
period.getDays() + "天");
}
}
时间戳与日期转换
import java.time.Instant;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.time.ZonedDateTime;
public class TimestampDemo {
public static void main(String[] args) {
// 获取当前时间戳
long currentTimestamp = System.currentTimeMillis();
System.out.println("当前时间戳(毫秒): " + currentTimestamp);
// 获取秒级时间戳
long secondsTimestamp = Instant.now().getEpochSecond();
System.out.println("当前时间戳(秒): " + secondsTimestamp);
// 时间戳转LocalDateTime
LocalDateTime dateTime = LocalDateTime.ofInstant(
Instant.ofEpochMilli(currentTimestamp),
ZoneId.systemDefault()
);
System.out.println("时间戳转日期: " + dateTime);
// LocalDateTime转时间戳
LocalDateTime now = LocalDateTime.now();
long timestamp = now.atZone(ZoneId.systemDefault()).toInstant().toEpochMilli();
System.out.println("日期转时间戳: " + timestamp);
}
}
实用工具类
import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAdjusters;
public class DateUtils {
// 日期格式化
public static String formatDate(LocalDate date, String pattern) {
return date.format(DateTimeFormatter.ofPattern(pattern));
}
// 字符串转日期
public static LocalDate parseDate(String dateStr, String pattern) {
return LocalDate.parse(dateStr, DateTimeFormatter.ofPattern(pattern));
}
// 获取某月的第一天
public static LocalDate getFirstDayOfMonth(LocalDate date) {
return date.with(TemporalAdjusters.firstDayOfMonth());
}
// 获取某月的最后一天
public static LocalDate getLastDayOfMonth(LocalDate date) {
return date.with(TemporalAdjusters.lastDayOfMonth());
}
// 判断是否为闰年
public static boolean isLeapYear(int year) {
return Year.isLeap(year);
}
// 计算年龄
public static int calculateAge(LocalDate birthDate) {
return Period.between(birthDate, LocalDate.now()).getYears();
}
// 获取两个日期之间的所有日期
public static List<LocalDate> getDatesBetween(LocalDate start, LocalDate end) {
List<LocalDate> dates = new ArrayList<>();
LocalDate current = start;
while (!current.isAfter(end)) {
dates.add(current);
current = current.plusDays(1);
}
return dates;
}
public static void main(String[] args) {
// 使用示例
LocalDate today = LocalDate.now();
System.out.println(" " + formatDate(today, "yyyy-MM-dd"));
System.out.println("当月第一天: " + getFirstDayOfMonth(today));
System.out.println("当月最后一天: " + getLastDayOfMonth(today));
System.out.println("2024年是否是闰年: " + isLeapYear(2024));
System.out.println("年龄: " + calculateAge(LocalDate.of(1990, 1, 1)) + "岁");
// 获取日期范围
List<LocalDate> dateRange = getDatesBetween(
LocalDate.of(2024, 1, 1),
LocalDate.of(2024, 1, 7)
);
System.out.println("日期范围: " + dateRange);
}
}
实际业务场景案例
import java.time.*;
import java.time.format.DateTimeFormatter;
import java.util.*;
public class BusinessDemo {
// 场景1：计算订单超时时间
public static boolean isOrderExpired(LocalDateTime orderTime, int expireHours) {
LocalDateTime expireTime = orderTime.plusHours(expireHours);
return LocalDateTime.now().isAfter(expireTime);
}
// 场景2：判断是否在营业时间内
public static boolean isInBusinessHours(LocalTime now) {
LocalTime openTime = LocalTime.of(9, 0);
LocalTime closeTime = LocalTime.of(18, 0);
return !now.isBefore(openTime) && !now.isAfter(closeTime);
}
// 场景3：计算工作日天数（排除周末）
public static long countWorkDays(LocalDate start, LocalDate end) {
long workDays = 0;
LocalDate current = start;
while (!current.isAfter(end)) {
if (current.getDayOfWeek() != DayOfWeek.SATURDAY &&
current.getDayOfWeek() != DayOfWeek.SUNDAY) {
workDays++;
}
current = current.plusDays(1);
}
return workDays;
}
// 场景4：生日提醒
public static boolean isBirthdaySoon(LocalDate birthDate, int daysBefore) {
LocalDate today = LocalDate.now();
LocalDate thisYearBirthday = birthDate.withYear(today.getYear());
// 如果今年的生日已过，计算明年
if (thisYearBirthday.isBefore(today)) {
thisYearBirthday = thisYearBirthday.plusYears(1);
}
long daysToBirthday = ChronoUnit.DAYS.between(today, thisYearBirthday);
return daysToBirthday >= 0 && daysToBirthday <= daysBefore;
}
public static void main(String[] args) {
// 使用示例
LocalDateTime orderTime = LocalDateTime.now().minusHours(23);
System.out.println("订单是否超时(24小时): " + isOrderExpired(orderTime, 24));
System.out.println("是否在营业时间: " + isInBusinessHours(LocalTime.now()));
LocalDate start = LocalDate.of(2024, 1, 1);
LocalDate end = LocalDate.of(2024, 1, 31);
System.out.println("工作日天数(1月): " + countWorkDays(start, end) + "天");
LocalDate birthday = LocalDate.of(1990, 1, 20);
System.out.println("生日是否在一周内: " + isBirthdaySoon(birthday, 7));
}
}
这些案例涵盖了Java日期时间处理的常见场景，您可以根据实际需求进行调整和使用，建议使用Java 8+的java.time包，因为它是线程安全的,API设计更合理。
