Grails - computer/browser locale doesn't affects i18n mechanism - grails

Question

I'm having a weird problem or maybe i failed to understand how Grails i18n mechanism works.
I inserted the following to my index.gsp file:
LocaleContextHolder.locale: '${org.springframework.context.i18n.LocaleContextHolder.locale}'
java.util.Locale.getDefault(): '${java.util.Locale.getDefault()}'
RequestContextUtils.getLocale(request): '${org.springframework.web.servlet.support.RequestContextUtils.getLocale(request)}'
session['SessionLocaleResolver.LOCALE']: '${session['org.springframework.web.servlet.i18n.SessionLocaleResolver.LOCALE']}'
This code snippet should print the Locale, and it does like so:
LocaleContextHolder.locale: 'iw'
java.util.Locale.getDefault(): 'en_US'
RequestContextUtils.getLocale(request): 'iw'
session['SessionLocaleResolver.LOCALE']: ''
The above is my default output when i run the given code snippet.
I tried to understand what exactly affects this variables so i did the next steps:
I changed Chrome's Locale
Settings --> Show advanced settings --> Language and input settings)
I changed my operating system's locale (Windows 7)
Control panel --> Region and language --> Format + Location + System locale
After those changes i rebooted my computer and expected the values of the locale variables to change, but they still remain the same.
I'm aware i can change the Locale with the ?lang parameter & with some code, but i'm interested in letting Grails to decide which Locale to pick.
What exactly affects those variables? how does Grails decide the machine's locale?

Answer 1

15.2 Changing Locales
By default the user locale is detected from the incoming Accept-Language header. However, you can provide users the capability to switch locales by simply passing a parameter called lang to Grails as a request parameter:
/book/list?lang=es
Grails will automatically switch the user's locale and store it in a cookie so subsequent requests will have the new header.
from here :
https://grails.github.io/grails-doc/2.4.3/guide/i18n.html
If you are deploying in tomcat you can set the locale in the catalina.sh script:
if [ -z "$LOGGING_MANAGER" ]; then
JAVA_OPTS="$JAVA_OPTS -Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager -Duser.language=en -Duser.region=US"
else
JAVA_OPTS="$JAVA_OPTS $LOGGING_MANAGER -Duser.language=en -Duser.region=US"
fi

Answer 2

I think the internationalization works when you pass lang parameter in the URL. It's mentioned in the documentation
By default the user locale is detected from the incoming Accept-Language header.
However, you can provide users the capability to switch locales by simply passing
a parameter called lang to Grails as a request parameter:
/book/list?lang=es
http://grails.github.io/grails-doc/latest/guide/i18n.html

Answer 3

By default the user Locale is detected from the incoming Accept-Language HTTP header, this header is generated by the browser that is used by the user.
Each browser determines the system Locale differently:
Internet Explorer uses the O/S Locale settings.
Firefox / Chrome let the user to decide what Locale to use (In the language settings).
See: http://www.w3.org/International/questions/qa-lang-priorities.en.php