How to get the Current Locale in GWT using LocaleI

问题:

I have tried to get the current locale on the client using the LocaleInfo class and the method getCurrentLocale(). However it always returns the value default locale no matter what regional and locale settings I have on the client machine.

The Date classes toLocaleString() method returns a locale specific string but the LocaleInfo doesn't seem to be able to get the systems Locale.

回答1:

Locales for GWT are not automatically obtained from the system/browser settings. As per the GET locale documentation the locale to use at run time can be set in one of two ways:

1. By specifying a locale request parameter in your application's URL. I.e. http://www.myapplication.com/?locale=es

2. By including a gwt:property meta tag in the host page:

   <meta name="gwt:property" content="locale=es" />

   This is the preferred method for production applications. Your host page can determine the user's locale in a number of ways including, but not limited to, allowing the user to configure a local or detecting their preferred locale based on the Accept-Language request header.

回答2:

To make your GWT app auto-detect your locale, just rename your base index.html file (the file that includes the "nocache.js" script) to index.jsp and add the following line to the section:

<meta name="gwt:property" content="locale=<%=request.getLocale()%>">

回答3:

It's almost impossible to accurately get the locale of the user in JavaScript so GWT doesn't even try [1].
LocaleInfo returns information about the locale selected among the ones you compiled in your app; that is, one of the locales you added using <extend-property name="locale" ... /> in your *.gwt.xml.

See https://developers.google.com/web-toolkit/doc/latest/DevGuideI18nLocale

[1] well, in recent versions it does try (using the browser's compile-time locale), but only to select one of the compiled-in locales, so that doesn't change anything to the behavior of LocaleInfo.