Java gets time of each time zone, gets the current time to GMT January 01, 1970 00:00 00 seconds

1. GMT is utc/gmt time, January 01, 1970 00:00 00 seconds (that is, utc+8 Beijing time January 01, 1970 08:00 00 seconds)
   The calculation code is as follows:
   

1  /**
 2 * Get the number of seconds from the specified time to Greenwich Mean Time
 3 * UTC: 01:00, 00:00, GMT, January 1, 1970 (UTC+8 Beijing time, January 01, 1970, 08:00:00)
 4 * @param time
 5 * @return
 6 */
 7 public static long diffSeconds(String time){
 8 Calendar calendar = Calendar.getInstance();
 9 
10 calendar.clear();
11 Date datetime = DatetimeUtil.toDateByDate14(time);
12 calendar.setTime(datetime);
13
14 TimeZone timeZone = TimeZone.getTimeZone("GMT+08:00");
15 calendar.setTimeZone(timeZone);
16 return calendar.getTimeInMillis()/1000;
17 }
18
19 public static void main(String[] args) throws Exception {
20
21 String datetime = DatetimeUtil.getDatetime();
22 System.out.println("================= Method One: calendar====================== =======");
23 System.out.println(diffSeconds(datetime));
24 System.out.println("================= Method 2: Calculate the time difference ===================== ========");
25 System.out.println(DatetimeUtil.diffSeconds("19700101080000", datetime, DatetimeUtil.PATTERN_YYYYMMDDHHMMSS));
26 System.out.println("================= Method 3: Using system===================== ========");
27 System.out.println(System.currentTimeMillis()/1000);
28 } 

2. use Java to take time in a specified time zone Beijing time, New York time, Bangalore time

1 /**
 2 * Take Beijing time
 3 * @return
 4 */
 5 public static String getBeijingTime(){
 6 return getFormatedDateString(8);
 7 }
 8     
 9     /**
10 * Take the time in Bangalore
11 * @return
12 */
13 public static String getBangaloreTime(){
14 return getFormatedDateString(5.5f);
15 }
16
17 /**
18 * Take New York time
19 * @return
20 */
21 public static String getNewyorkTime(){
22 return getFormatedDateString(-5);
twenty three     }
twenty four     
25 /**
26 * This function is non-original. Searching from the Internet, timeZoneOffset was originally int type, adjusted to float type for Bangalore
27 * timeZoneOffset indicates the time zone. For example, China generally uses the East 8th district, so timeZoneOffset is 8
28 * @param timeZoneOffset
29 * @return
30 */
31 public static String getFormatedDateString(float timeZoneOffset){
32 if (timeZoneOffset > 13 || timeZoneOffset < -12) {
33 timeZoneOffset = 0;
34 }
35
36 int newTime=(int)(timeZoneOffset * 60 * 60 * 1000);
37 TimeZone timeZone;
38 String[] ids = TimeZone.getAvailableIDs(newTime);
39 if (ids.length == 0) {
40 timeZone = TimeZone.getDefault();
41 } else {
42 timeZone = new SimpleTimeZone(newTime, ids[0]);
43 }
44
45 SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
46 sdf.setTimeZone(timeZone);
47 return sdf.format(new Date());
48 }

Java gets time of each time zone, gets the current time to GMT January 01, 1970 00:00 00 seconds