服务器的时区问题

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我是靠谱客的博主儒雅绿茶，最近开发中收集的这篇文章主要介绍服务器的时区问题，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1、需求：分别统计本月、本周、当天创建的优惠劵数量
2、需求分析：在后台分别获取本月、本周、当天的开始时间，用当天的开始时间举例，获取方式为将目前的系统时间的时分秒去掉，就获取到了当天的开始时间：代码为：

public static String getNowStartDay() {
String property = System.getProperty("user.timezone");
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd 00:00:00");
sdf.setTimeZone(TimeZone.getTimeZone(property));
return sdf.format(Calendar.getInstance().getTime());
}

这样就忽略了时区的问题，按正常情况下往前推8小时，就会算到前一天的16:00:00。
3、问题处理思路：以某个地区的时间为参照，比如以北京上海的时间为参照，计算出服务器当地的时间与北京上海时间的时间差，然后在计算当天开始时间将上面的时间差处理掉，本月和本周的开始时间同理，代码为：

	/**
* 获得今天时间的开始时间:yyyy-MM-dd
HH:mm:ss
*/
public static String getNowStartDay() {
String property = System.getProperty("user.timezone");
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
sdf.setTimeZone(TimeZone.getTimeZone(property));
Calendar instance = Calendar.getInstance();
//处理当地时间与北京时间的时区偏差
instance.set(Calendar.HOUR,0);
instance.set(Calendar.MINUTE,0);
instance.set(Calendar.SECOND,0);
instance.add(Calendar.HOUR, getBetweenCurrentToBeijingTime());
return sdf.format(instance.getTime());
}
/**
* 获得当前时间:yyyy-MM-dd
HH:mm:ss
*/
public static String getNowDateStr() {
String property = System.getProperty("user.timezone");
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
sdf.setTimeZone(TimeZone.getTimeZone(property));
return sdf.format(Calendar.getInstance().getTime());
}
/**
* 获得本月第一天:yyyy-MM-dd
HH:mm:ss
*/
public static String getMonthStartDay() {
Calendar c = Calendar.getInstance();
c.add(Calendar.MONTH, 0);
c.set(c.get(Calendar.YEAR), c.get(Calendar.MONTH), c.getActualMaximum(Calendar.DAY_OF_MONTH), 23, 59, 59);
SimpleDateFormat startSdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
//处理当地时间与北京时间的时区偏差
c.set(Calendar.DAY_OF_MONTH,1);
c.set(Calendar.HOUR,0);
c.set(Calendar.MINUTE,0);
c.set(Calendar.SECOND,0);
c.add(Calendar.HOUR, getBetweenCurrentToBeijingTime());
return startSdf.format(c.getTime());
}
/**
* 获取本周的开始时间:yyyy-MM-dd
HH:mm:ss
*/
public static Date getBeginDayOfCurrentWeek() {
Date date = new Date();
if (date == null) {
return null;
}
Calendar cal = Calendar.getInstance();
cal.setTime(date);
int dayofweek = cal.get(Calendar.DAY_OF_WEEK);
if (dayofweek == 1) {
dayofweek += 7;
}
cal.add(Calendar.DATE, 2 - dayofweek);
return getDayStartTime(cal.getTime());
}
// 获取某个日期的开始时间
public static Timestamp getDayStartTime(Date d) {
Calendar calendar = Calendar.getInstance();
if (null != d)
calendar.setTime(d);
calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),
calendar.get(Calendar.DAY_OF_MONTH), 0, 0, 0);
calendar.set(Calendar.MILLISECOND, 0);
//处理当地时间与北京时间的时区偏差
calendar.set(Calendar.HOUR,0);
calendar.set(Calendar.MINUTE,0);
calendar.set(Calendar.SECOND,0);
calendar.add(Calendar.HOUR, getBetweenCurrentToBeijingTime());
return new Timestamp(calendar.getTimeInMillis());
}
public static int getBetweenCurrentToBeijingTime(){
//获取当前地区的时间毫秒
Calendar calendar = Calendar.getInstance();
long currentTimeInMillis = calendar.getTimeInMillis();
//获取北京上海地区的时间毫秒
calendar.setTimeZone(TimeZone.getTimeZone("Asia/Shanghai"));
Calendar beijingCalendar = Calendar.getInstance();
beijingCalendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH),
calendar.get(Calendar.HOUR_OF_DAY), calendar.get(Calendar.MINUTE), calendar.get(Calendar.SECOND));
long beijingTimeInMillis = beijingCalendar.getTimeInMillis();
//计算两个时间的小时差
long between = currentTimeInMillis - beijingTimeInMillis;
int hour = ((int)between / (60 * 60 * 1000));
return hour;
}