Java获取指定时区的时间戳

1. 前言

本文主要讲，在Java中如何通过一个标准格式时间字符串（"yyyy-MM-dd HH:mm:ss"），来获取其对应的各个时区的时间戳信息。

2. 代码示例

功能代码：
获取时间字符串对应的指定时区的时间戳

public static long getTimeZoneTimeStr(String dateStr,String timeZone) {
        long result = 0L;
        int year;
        int month;
        int day;
        int hour;
        int minute;
        int second;
        Calendar calendarTime = Calendar.getInstance();
        TimeZone tz = TimeZone.getTimeZone(timeZone);
        calendarTime.setTimeZone(tz);
        if (null != dateStr && 14 == dateStr.length()) {
            year = Integer.parseInt(dateStr.substring(0, 4));
            month = Integer.parseInt(dateStr.substring(4, 6));
            day = Integer.parseInt(dateStr.substring(6, 8));
            hour = Integer.parseInt(dateStr.substring(8, 10));
            minute = Integer.parseInt(dateStr.substring(10, 12));
            second = Integer.parseInt(dateStr.substring(12, 14));
            calendarTime.set(1, year);
            calendarTime.set(2, month - 1);
            calendarTime.set(5, day);
            calendarTime.set(11, hour);
            calendarTime.set(12, minute);
            calendarTime.set(13, second);
            result = calendarTime.getTime().getTime();
        }else if (null != dateStr && 19 == dateStr.length()) {
            year = Integer.parseInt(dateStr.substring(0, 4));
            month = Integer.parseInt(dateStr.substring(5, 7));
            day = Integer.parseInt(dateStr.substring(8, 10));
            hour = Integer.parseInt(dateStr.substring(11, 13));
            minute = Integer.parseInt(dateStr.substring(14, 16));
            second = Integer.parseInt(dateStr.substring(17, 19));
            calendarTime.set(1, year);
            calendarTime.set(2, month - 1);
            calendarTime.set(5, day);
            calendarTime.set(11, hour);
            calendarTime.set(12, minute);
            calendarTime.set(13, second);
            result = calendarTime.getTime().getTime();
        }

        return result;
    }

调用示例：

public static void main(String[] args) {
        System.out.println("-------------------- 2019-09-24 00:00:00 -----------------------");
        System.out.println("local: "+generateDateStamp("2019-09-24 00:00:00"));
        System.out.println("GMT+0800: "+getUTCTimeStr("2019-09-24 00:00:00","GMT+0800"));
        System.out.println("GMT: "+getUTCTimeStr("2019-09-24 00:00:00","GMT"));
        System.out.println("UTC: "+getUTCTimeStr("2019-09-24 00:00:00","UTC"));

        System.out.println("-------------------- 2019-09-23 16:00:00 -----------------------");
        System.out.println("local: "+generateDateStamp("2019-09-23 16:00:00"));
        System.out.println("GMT+0800: "+getUTCTimeStr("2019-09-23 16:00:00","GMT+0800"));
        System.out.println("GMT: "+getUTCTimeStr("2019-09-23 16:00:00","GMT"));
        System.out.println("UTC: "+getUTCTimeStr("2019-09-23 16:00:00","UTC"));
    }

程序运行结果：

-------------------- 2019-09-24 00:00:00 -----------------------
local: 1569254400094
GMT+0800: 1569254400118
GMT: 1569283200118
UTC: 1569283200119
-------------------- 2019-09-23 16:00:00 -----------------------
local: 1569225600119
GMT+0800: 1569225600119
GMT: 1569254400119
UTC: 1569254400119

3. 总结

运行结果可以看出，在Java中Date.getTime()获取到的时间戳其实是东8区的时间“2019-09-24 00:00:00”（即返回的是北京时间1970年01月1日0点0分0秒以来的毫秒数，对应UTC时间1970年01月1日8点0分0秒以来的毫秒数，其数值大小等于0时区的“2019-09-23 16:00:00”所对应的时间戳）所对应得时间戳。