AcceptHeaderLocaleResolver should allow to define a default Locale [SPR-14312]

[spring-projects-issues]

Oliver Drotbohm opened SPR-14312 and commented

It would be cool if AcceptHeaderLocaleResolver would allow configuring a default Locale just as CookieLocaleResolver does. The use case is that I'd like to allow clients to explicit request a certain local but at the same time make sure that a well-defined default is used, independently of the system language (to prevent different deployment locations from changing the default).

It looks like we'd have to check whether the Accept-Language header is set explicitly to find out whether to use the configured default in the first place.

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Issue Links:

• Flexible locale resolution based on supported languages [SPR-13330] #17915 Flexible locale resolution based on supported languages
• Mock MVC / RequestBuilder should handle Accept-Language header appropriately [SPR-15209] #19773 Mock MVC / RequestBuilder should handle Accept-Language header appropriately
• Revise AcceptHeaderLocaleResolver default locale handling [SPR-15426] #19987 Revise AcceptHeaderLocaleResolver default locale handling

Referenced from: commits 8343ce9

[spring-projects-issues]

Rossen Stoyanchev commented

Oops, Juergen I didn't see you assigned that one already. I had chatted with Ollie about it just before.

[spring-projects-issues]

Juergen Hoeller commented

No worries, I'm happy for it to be picked up for 4.3 GA still. Assigning it to you for the time being :-)

[spring-projects-issues]

Tadas Krivickas commented

The current implementation does not fallback to default locale if the client-requested locale is not supported.
Consider this (currently failing) test case:

    @Test
    public void resolvePreferredNotSupported2() {
        this.resolver.setSupportedLocales(Arrays.asList(US, JAPAN));
        this.resolver.setDefaultLocale(Locale.JAPAN);

        MockHttpServletRequest request = new MockHttpServletRequest();
        request.addHeader("Accept-Language", KOREA.toString());
        request.setPreferredLocales(Collections.singletonList(KOREA));

        assertEquals(Locale.JAPAN, this.resolver.resolveLocale(request));
    }

Shouldn't default locale be used as a fallback?

https://github.com/spring-projects/spring-framework/blob/master/spring-webmvc/src/main/java/org/springframework/web/servlet/i18n/AcceptHeaderLocaleResolver.java#L100

Related: #17915

[spring-projects-issues]

Juergen Hoeller commented

Good point! I've created #19987 to track such a revision.