Java中常用的日期操作方法

日常项目当中经常会用到操作日期，抽出时间总结了一下，欢迎和大家多多沟通学习，如有任何改进意见和建议，我的QQ是1243672，欢迎联系哦。

/**
 * 日期操作类
 * 开发公司:北京东达悦科技有限公司
 * 开发人:宋海鹏
 * 最后更新日期:2013-09-10
 */
package com.imstudio.common;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;

public class DatetimeHelper {

    private static String datePattern = "yyyy-MM-dd";
    private static String timePattern = datePattern + " HH:mm:ss";
    private static String minDate = "1900-01-01";

    public static String getDatePattern() {
        return datePattern;
    }

    public static String getTimePattern() {
        return timePattern;
    }

    public static final String DatetimeToString(Date date, String pattern) {
        SimpleDateFormat df = null;
        String dateString = "";
        if (date != null) {
            df = new SimpleDateFormat(pattern);
            dateString = df.format(date);
        }
        return dateString;
    }

    public static final String DateToString(Date date) {
        return DatetimeToString(date, datePattern);
    }

    public static final String DatetimeToString(Date date) {
        return DatetimeToString(date, timePattern);
    }

    public static final Date StringToDatetime(String date, String pattern) {
        SimpleDateFormat df = null;
        Date dateValue = null;
        df = new SimpleDateFormat(pattern);
        try {
            dateValue = (Date) df.parse(date);
        } catch (ParseException pre) {
            return null;
        }

        return dateValue;
    }

    public static final Date StringToDate(String date) {
        return StringToDatetime(date, datePattern);
    }

    public static final Date StringToDatetime(String date) {
        return StringToDatetime(date, timePattern);
    }

    public static final String Now(String pattern) {
        Date dt = new Date();
        SimpleDateFormat df = new SimpleDateFormat(pattern);
        return df.format(dt);
    }

    public static final String Now() {
        return Now(timePattern);
    }

    public static final String Today() {
        return Now(datePattern);
    }

    public static final String Today(String pattern) {
        return Now(pattern);
    }

    public static final Date MinDate() {
        return StringToDate(minDate);
    }

    public static final Long DateDiff(Date start, Date end) {
        long days = 0;
        days = (start.getTime() - end.getTime()) / (60 * 60 * 24 * 1000);
        return days;
    }

    public static final Long DateDiff(String start, String end) {
        return DateDiff(StringToDatetime(start), StringToDatetime(end));
    }

    public static final Long DateDiff(String end) {
        return DateDiff(StringToDatetime(Today()), StringToDatetime(end));
    }

    @SuppressWarnings("deprecation")
    public static final Long Age(Date today, Date birthday) {
        long age = 0;
        age = today.getYear() - birthday.getYear();
        if (today.getMonth() == birthday.getMonth()) {
            age = (today.getDay() < birthday.getDay()) ? age - 1 : age;
        } else {
            age = (today.getMonth() > birthday.getMonth()) ? age : age - 1;
        }
        return age;
    }
}