用java写一个日期工具类

以下是一个简单的Java日期工具类，包含常用的日期操作方法：

import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class DateUtil {
    
    // 格式化日期
    public static String formatDate(Date date, String pattern) {
        DateFormat dateFormat = new SimpleDateFormat(pattern);
        return dateFormat.format(date);
    }
    
    // 获取当前日期
    public static Date getCurrentDate() {
        Calendar calendar = Calendar.getInstance();
        return calendar.getTime();
    }
    
    // 获取当前日期字符串
    public static String getCurrentDateString(String pattern) {
        Date currentDate = getCurrentDate();
        return formatDate(currentDate, pattern);
    }
    
    // 获取给定日期的年份
    public static int getYear(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.YEAR);
    }
    
    // 获取给定日期的月份
    public static int getMonth(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.MONTH) + 1;
    }
    
    // 获取给定日期的天数
    public static int getDay(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.DAY_OF_MONTH);
    }
    
    // 获取给定日期的小时数
    public static int getHour(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.HOUR_OF_DAY);
    }
    
    // 获取给定日期的分钟数
    public static int getMinute(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.MINUTE);
    }
    
    // 获取给定日期的秒数
    public static int getSecond(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.SECOND);
    }
    
    // 获取给定日期的毫秒数
    public static long getMillis(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.getTimeInMillis();
    }
    
    // 获取给定日期是一周中的第几天
    public static int getDayOfWeek(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.DAY_OF_WEEK);
    }
    
    // 获取给定日期是一年中的第几天
    public static int getDayOfYear(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.get(Calendar.DAY_OF_YEAR);
    }
    
    // 获取给定日期所在月份的天数
    public static int getDaysOfMonth(Date date) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        return calendar.getActualMaximum(Calendar.DAY_OF_MONTH);
    }
    
    // 在给定日期的基础上加上/减去指定的年数
    public static Date addYears(Date date, int years) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.YEAR, years);
        return calendar.getTime();
    }
    
    // 在给定日期的基础上加上/减去指定的月数
    public static Date addMonths(Date date, int months) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.MONTH, months);
        return calendar.getTime();
    }
    
    // 在给定日期的基础上加上/减去指定的天数
    public static Date addDays(Date date, int days) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.DAY_OF_MONTH, days);
        return calendar.getTime();
    }
    
    // 在给定日期的基础上加上/减去指定的小时数
    public static Date addHours(Date date, int hours) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.HOUR_OF_DAY, hours);
        return calendar.getTime();
    }
    
    // 在给定日期的基础上加上/减去指定的分钟数
    public static Date addMinutes(Date date, int minutes) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.MINUTE, minutes);
        return calendar.getTime();
    }
    
    // 在给定日期的基础上加上/减去指定的秒数
    public static Date addSeconds(Date date, int seconds) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.SECOND, seconds);
        return calendar.getTime();
    }
    
    // 在给定日期的基础上加上/减去指定的毫秒数
    public static Date addMillis(Date date, long millis) {
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        calendar.add(Calendar.MILLISECOND, (int) millis);
        return calendar.getTime();
    }
    
}