I'm about to deal with time zones in Grails (Java). Here Java 7 is used and Grails 2.3.7.
I have a WebApp where each user is assigned a timeZoneID. If a user enters a date, it only consists of day, month and year. I want to set the time automatically.
The date entered by the user (e.g. 01.10.2018, german format) should be saved in the DB (MySQL) in UTC format.
When the date is displayed to the user, it is formatted according to the user's time zone.
Many timeZoneIDs work fine with my code (Europe/Berlin, Hont_Kong, ....), but America/New_York for example doesn't and I don't understand why.
The code to parse and save a date is as follows:
//endDate is 31.10.2018
def format = messageService.getMessage(code: 'default.date.short.format')
//--> dd.MM.yyyy for DE and MM/dd/yy for EN
println("Use format: " + format)
SimpleDateFormat sdf = new SimpleDateFormat(format);
//set timezone (America/New_York)
sdf.setTimeZone(TimeZone.getTimeZone(user.timeZoneID))
//parse endDate
Date parsedEndDate = sdf.parse(endDate)
//create a calendar instance (e.g. America/New_York)
Calendar calendarEnd = Calendar.getInstance(TimeZone.getTimeZone(user.timeZoneID));
//set time
calendarEnd.setTime(parsedEndDate);
//set hour/minute automatically
calendarEnd.set(Calendar.HOUR_OF_DAY, 23)
calendarEnd.set(Calendar.MINUTE, 59)
//at this point it should be 31.10.2018, 23:59 (german format, timezone America/New_York)
//Convert to UTC before saving date in DB (MySQL)
calendarEnd.setTimeZone(TimeZone.getTimeZone('UTC'))
//save the date
def obj = new Foo(date:calendarEnd).save(flush:true)
The code inside my view (gsp) to display a date is as follows:
<g:formatDate
timeZone="${user.timeZoneID}"
date="${fooInstance?.calendarEnd}"
format="${message(code: 'default.date.format', default: 'MM/dd/yyyy, hh:mm a')}"/>
Inside the DB I get 2018-11-01 00:59:00
Inside my view (GSP) it results in 31.10.2018, 19:59, instead of 31.10.2018, 23:59
Thank you very much for your help.
The problem is in convert step:
//Convert to UTC before saving date in DB (MySQL)
calendarEnd.setTimeZone(TimeZone.getTimeZone('UTC'))
Because you are just changing the time zone so it is using the given time and date as if it is the UTC time zone.
Java 1.7 and before are somewhat unwieldy in regards to the Time API so a lot of people use Joda Time.
Otherwise you can use the advice from this question resulting in something like:
calendarEnd.add(Calendar.MILLISECOND, TimeZone.getTimeZone('UTC').getOffset(parsedEndDate.getTime())
This is not tested and could be wrong as the offset calculation might be diffrent
I want to store all date time and when a user wants to get information. The server must to return data with datetime and 3rd party devices (like Android , IOS, Web apps) should convert that datetime for specific timezone. The basic goal is store all date timezone with "0" timezone
You can use Java8 ZonedDateTime to get time in UTC. My assumption is 0 timezone means UTC
ZonedDateTime.now(ZoneOffset.UTC);// This will give current time in UTC
To convert ZontedDateTime , You can put GMT,US/Central etc in the config file
public static ZonedDateTime getDateinTimeZone(String timeZone,String dateInSting )
{
return ZonedDateTime.parse(dateInSting).now(ZoneId.of(timeZone));
}
I have to store UTC dateTime in DB.
I have converted the dateTime given in specific timezone to UTC. for that I followed the below code.
My input dateTime is "20121225 10:00:00 Z" timezone is "Asia/Calcutta"
My Server/DB(oracle) is running in the same timezone(IST) "Asia/Calcutta"
Get the Date object in this specific Timezone
String date = "20121225 10:00:00 Z";
String timeZoneId = "Asia/Calcutta";
TimeZone timeZone = TimeZone.getTimeZone(timeZoneId);
DateFormat dateFormatLocal = new SimpleDateFormat("yyyyMMdd HH:mm:ss z");
//This date object is given time and given timezone
java.util.Date parsedDate = dateFormatLocal.parse(date + " "
+ timeZone.getDisplayName(false, TimeZone.SHORT));
if (timeZone.inDaylightTime(parsedDate)) {
// We need to re-parse because we don't know if the date
// is DST until it is parsed...
parsedDate = dateFormatLocal.parse(date + " "
+ timeZone.getDisplayName(true, TimeZone.SHORT));
}
//assigning to the java.sql.TimeStamp instace variable
obj.setTsSchedStartTime(new java.sql.Timestamp(parsedDate.getTime()));
Store into DB
if (tsSchedStartTime != null) {
stmt.setTimestamp(11, tsSchedStartTime);
} else {
stmt.setNull(11, java.sql.Types.DATE);
}
OUTPUT
DB (oracle) has stored the same given dateTime: "20121225 10:00:00 not in UTC.
I have confirmed from the below sql.
select to_char(sched_start_time, 'yyyy/mm/dd hh24:mi:ss') from myTable
My DB server also running on the same timezone "Asia/Calcutta"
It gives me the below appearances
Date.getTime() is not in UTC
Or Timestamp is has timezone impact while storing into DB
What am I doing wrong here?
One more question:
Will timeStamp.toString() print in local timezone like java.util.date does? Not UTC?
Although it is not explicitly specified for setTimestamp(int parameterIndex, Timestamp x) drivers have to follow the rules established by the setTimestamp(int parameterIndex, Timestamp x, Calendar cal) javadoc:
Sets the designated parameter to the given java.sql.Timestamp value, using the given Calendar object. The driver uses the Calendar object to construct an SQL TIMESTAMP value, which the driver then sends to the database. With a Calendar object, the driver can calculate the timestamp taking into account a custom time zone. If no Calendar object is specified, the driver uses the default time zone, which is that of the virtual machine running the application.
When you call with setTimestamp(int parameterIndex, Timestamp x) the JDBC driver uses the time zone of the virtual machine to calculate the date and time of the timestamp in that time zone. This date and time is what is stored in the database, and if the database column does not store time zone information, then any information about the zone is lost (which means it is up to the application(s) using the database to use the same time zone consistently or come up with another scheme to discern timezone (ie store in a separate column).
For example: Your local time zone is GMT+2. You store "2012-12-25 10:00:00 UTC". The actual value stored in the database is "2012-12-25 12:00:00". You retrieve it again: you get it back again as "2012-12-25 10:00:00 UTC" (but only if you retrieve it using getTimestamp(..)), but when another application accesses the database in time zone GMT+0, it will retrieve the timestamp as "2012-12-25 12:00:00 UTC".
If you want to store it in a different timezone, then you need to use the setTimestamp(int parameterIndex, Timestamp x, Calendar cal) with a Calendar instance in the required timezone. Just make sure you also use the equivalent getter with the same time zone when retrieving values (if you use a TIMESTAMP without timezone information in your database).
So, assuming you want to store the actual GMT timezone, you need to use:
Calendar cal = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
stmt.setTimestamp(11, tsSchedStartTime, cal);
With JDBC 4.2 a compliant driver should support java.time.LocalDateTime (and java.time.LocalTime) for TIMESTAMP (and TIME) through get/set/updateObject. The java.time.Local* classes are without time zones, so no conversion needs to be applied (although that might open a new set of problems if your code did assume a specific time zone).
I think the correct answer should be java.sql.Timestamp is NOT timezone specific. Timestamp is a composite of java.util.Date and a separate nanoseconds value. There is no timezone information in this class. Thus just as Date this class simply holds the number of milliseconds since January 1, 1970, 00:00:00 GMT + nanos.
In PreparedStatement.setTimestamp(int parameterIndex, Timestamp x, Calendar cal)
Calendar is used by the driver to change the default timezone. But Timestamp still holds milliseconds in GMT.
API is unclear about how exactly JDBC driver is supposed to use Calendar. Providers seem to feel free about how to interpret it, e.g. last time I worked with MySQL 5.5 Calendar the driver simply ignored Calendar in both PreparedStatement.setTimestamp and ResultSet.getTimestamp.
The answer is that java.sql.Timestamp is a mess and should be avoided. Use java.time.LocalDateTime instead.
So why is it a mess? From the java.sql.Timestamp JavaDoc, a java.sql.Timestamp is a "thin wrapper around java.util.Date that allows the JDBC API to identify this as an SQL TIMESTAMP value". From the java.util.Date JavaDoc, "the Date class is intended to reflect coordinated universal time (UTC)". From the ISO SQL spec a TIMESTAMP WITHOUT TIME ZONE "is a data type that is datetime without time zone". TIMESTAMP is a short name for TIMESTAMP WITHOUT TIME ZONE. So a java.sql.Timestamp "reflects" UTC while SQL TIMESTAMP is "without time zone".
Because java.sql.Timestamp reflects UTC its methods apply conversions. This causes no end of confusion. From the SQL perspective it makes no sense to convert a SQL TIMESTAMP value to some other time zone as a TIMESTAMP has no time zone to convert from. What does it mean to convert 42 to Fahrenheit? It means nothing because 42 does not have temperature units. It's just a bare number. Similarly you can't convert a TIMESTAMP of 2020-07-22T10:38:00 to Americas/Los Angeles because 2020-07-22T10:30:00 is not in any time zone. It's not in UTC or GMT or anything else. It's a bare date time.
java.time.LocalDateTime is also a bare date time. It does not have a time zone, exactly like SQL TIMESTAMP. None of its methods apply any kind of time zone conversion which makes its behavior much easier to predict and understand. So don't use java.sql.Timestamp. Use java.time.LocalDateTime.
LocalDateTime ldt = rs.getObject(col, LocalDateTime.class);
ps.setObject(param, ldt, JDBCType.TIMESTAMP);
You can use the below method to store the timestamp in database specific to your desired zone/zone Id.
ZonedDateTime zdt = ZonedDateTime.now(ZoneId.of("Asia/Calcutta")) ;
Timestamp timestamp = Timestamp.valueOf(zdt.toLocalDateTime());
A common mistake people do is use LocaleDateTime to get the timestamp of that instant which discards any information specif to your zone even if you try to convert it later. It does not understand the Zone.
Please note Timestamp is of the class java.sql.Timestamp.
For Mysql, we have a limitation.
In the driver Mysql doc, we have :
The following are some known issues and limitations for MySQL
Connector/J: When Connector/J retrieves timestamps for a daylight
saving time (DST) switch day using the getTimeStamp() method on the
result set, some of the returned values might be wrong. The errors can
be avoided by using the following connection options when connecting
to a database:
useTimezone=true
useLegacyDatetimeCode=false
serverTimezone=UTC
So, when we do not use this parameters and we call setTimestamp or getTimestamp with calendar or without calendar, we have the timestamp in the jvm timezone.
Example :
The jvm timezone is GMT+2.
In the database, we have a timestamp : 1461100256 = 19/04/16 21:10:56,000000000 GMT
Properties props = new Properties();
props.setProperty("user", "root");
props.setProperty("password", "");
props.setProperty("useTimezone", "true");
props.setProperty("useLegacyDatetimeCode", "false");
props.setProperty("serverTimezone", "UTC");
Connection con = DriverManager.getConnection(conString, props);
......
Calendar nowGMT = Calendar.getInstance(TimeZone.getTimeZone("GMT"));
Calendar nowGMTPlus4 = Calendar.getInstance(TimeZone.getTimeZone("GMT+4"));
......
rs.getTimestamp("timestampColumn");//Oracle driver convert date to jvm timezone and Mysql convert date to GMT (specified in the parameter)
rs.getTimestamp("timestampColumn", nowGMT);//convert date to GMT
rs.getTimestamp("timestampColumn", nowGMTPlus4);//convert date to GMT+4 timezone
The first method returns : 1461100256000 = 19/04/2016 - 21:10:56 GMT
The second method returns : 1461100256000 = 19/04/2016 - 21:10:56 GMT
The third method returns : 1461085856000 = 19/04/2016 - 17:10:56 GMT
Instead of Oracle, when we use the same calls, we have :
The first method returns : 1461093056000 = 19/04/2016 - 19:10:56 GMT
The second method returns : 1461100256000 = 19/04/2016 - 21:10:56 GMT
The third method returns : 1461085856000 = 19/04/2016 - 17:10:56 GMT
NB :
It is not necessary to specify the parameters for Oracle.
It is specific from your driver. You need to supply a parameter in your Java program to tell it the time zone you want to use.
java -Duser.timezone="America/New_York" GetCurrentDateTimeZone
Further this:
to_char(new_time(sched_start_time, 'CURRENT_TIMEZONE', 'NEW_TIMEZONE'), 'MM/DD/YY HH:MI AM')
May also be of value in handling the conversion properly. Taken from here
If your problem is to get a timestamp of the local zone, you can use this:
Timestamp.from(Instant.now()).toLocalDateTime()
I have problems with formatting server time. Server is on central time I guess. I need to format following string 2016-08-22T10:29:22 in default zone (Central European Summer Time = GMT+2). I tried with Joda-Time library, I need to get 12:29:22, but I only managed to get same date with +02:00 the end, with code like this:
DateTimeFormatter formatter = DateTimeFormat.forPattern("yyyy-MM-dd'T'HH:mm:ss");
DateTime dateTime = formatter.withZone(DateTimeZone.getDefault()).parseDateTime(time);
Output of this code is: 2016-08-22T10:29:22.000+02:00, when I try to dateTime.getHourOfDay(); - I getting 10 again.
Where am I going wrong?
2016-08-22T10:29:22 in default zone (Central European Summer Time = GMT+2).
10:29 in GMT+2 is 10:29 in GMT+2 and 8:29 in GMT, and the 2016-08-22T10:29:22 simply lacks information of timezone. So either make server return timezone or manually add it (i.e. append Z) prior converting.
From few days I am fighting with different Timezone issues of server and GWT client. but cannot get any success.
Scenario is Server is in UTC timezone let say Client A is in IST timezone.
When client select a date (with time) I pushed to server but date is automatically changed to server's timezone. I dig around this issue and I found multiple solutions like
create custom serializer (No idea how to do that can't found any proper example)
transfer date as a string to server and convert it to server timezone and store it. and when fetching data convert again from server's timezone to client local timezone. sounds good idea.
So my query is.
Any other solutions?
which is best way to manage this ?
any sample code or link?
Simply format the date in UTC format at client side and pass the date as string to the server and store the data in UTC format in database as well.
On the server side everything would be fine, since formatting the date would use the timezone of the server, which is what the date is stored in. On the client side, however, GWT will use the timezone of the client machine, and so there could be a discrepancy.
Sample code:
DateTimeFormat f = DateTimeFormat.getFormat("MMM dd yyyy");
TimeZoneConstants t = (TimeZoneConstants) GWT.create(TimeZoneConstants.class)
TimeZone est = TimeZone.createTimeZone(t.americaNewYork());
int offset = est.isDaylightTime(date) ? +240 : +300;
TimeZone tz = TimeZone.createTimeZone(offset);
String date = f.format(user.getBirthDate(), est);
There are a few other possible solutions, but one of these two might do the trick.
How do I get GWT DateTimeFormat to display using the server TimeZone, rather than the client's?