Locales作为Spring MVC中URL的一部分

Question

我现在正在寻找多语言Web应用程序的框架.目前在我看来,最好的选择是Spring MVC.但是我面对的事实是开发人员的所有指导方针都建议使用LocaleChangeInterceptor以这种方式切换语言:

http://www.somesite.com/action/?locale=en

不幸的是,我想避免这种情况有很多原因.我怎样才能使语言代码成为URL的重要组成部分？例如:

http://www.somesite.com/en/action

谢谢.

UPD:我找到了以下解决方案.它尚未完成,但有效.解决方案包括两部分 - servlet过滤器和区域设置解析器bean.它看起来有点hackish,但我没有看到解决这个问题的其他方法.

public class LocaleFilter implements Filter
{

    ...

    private static final String DEFAULT_LOCALE = "en";
    private static final String[] AVAILABLE_LOCALES = new String[] {"en", "ru"};

    public LocaleFilter() {} 

    private List<String> getSevletRequestParts(ServletRequest request)
    {
        String[] splitedParts = ((HttpServletRequest) request).getServletPath().split("/");
        List<String> result = new ArrayList<String>();

        for (String sp : splitedParts)
        {
            if (sp.trim().length() > 0)
                result.add(sp);
        }

        return result;
    }

    private Locale getLocaleFromRequestParts(List<String> parts)
    {
        if (parts.size() > 0)
        {
            for (String lang : AVAILABLE_LOCALES)
            {
                if (lang.equals(parts.get(0)))
                {
                    return new Locale(lang);
                }
            }
        }

        return null;
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
                         FilterChain chain) throws IOException, ServletException
    {
        List<String> requestParts = this.getSevletRequestParts(request);
        Locale locale = this.getLocaleFromRequestParts(requestParts);

        if (locale != null)
        {
            request.setAttribute(LocaleFilter.class.getName() + ".LOCALE", locale);

            StringBuilder sb = new StringBuilder();
            for (int i = 1; i < requestParts.size(); i++)
            {
                sb.append('/');
                sb.append((String) requestParts.get(i));
            }

            RequestDispatcher dispatcher = request.getRequestDispatcher(sb.toString());
            dispatcher.forward(request, response);
        }
        else
        {
            request.setAttribute(LocaleFilter.class.getName() + ".LOCALE", new Locale(DEFAULT_LOCALE));
            chain.doFilter(request, response);
        }
    }

    ...
}

public class FilterLocaleResolver implements LocaleResolver
{

    private Locale DEFAULT_LOCALE = new Locale("en");

    @Override
    public Locale resolveLocale(HttpServletRequest request)
    {
        Locale locale = (Locale) request.getAttribute(LocaleFilter.class.getName() + ".LOCALE");
        return (locale != null ? locale : DEFAULT_LOCALE);
    }

    @Override
    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale)
    {
        request.setAttribute(LocaleFilter.class.getName() + ".LOCALE", locale);
    }

}

因此,无需在控制器中的每个操作中映射区域设置.以下示例将正常工作:

@Controller
@RequestMapping("/test")
public class TestController
{

    @RequestMapping("action")
    public ModelAndView action(HttpServletRequest request, HttpServletResponse response)
    {
        ModelAndView mav = new ModelAndView("test/action");
        ...
        return mav;
    }

}

Answer 1

我使用Filter和Interceptor的组合实现了非常相似的东西.

过滤器提取第一个路径变量,如果它是一个有效的语言环境,则将其设置为请求属性,从请求的URI的开头剥离它,并将请求转发给新的URI.

public class PathVariableLocaleFilter extends OncePerRequestFilter {
private static final Logger LOG = LoggerFactory.getLogger(PathVariableLocaleFilter.class);

@Override
protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain)
        throws ServletException, IOException {
    String url = defaultString(request.getRequestURI().substring(request.getContextPath().length()));
    String[] variables = url.split("/");

    if (variables.length > 1 && isLocale(variables[1])) {
        LOG.debug("Found locale {}", variables[1]);
        request.setAttribute(LOCALE_ATTRIBUTE_NAME, variables[1]);
        String newUrl = StringUtils.removeStart(url, '/' + variables[1]);
        LOG.trace("Dispatching to new url \'{}\'", newUrl);
        RequestDispatcher dispatcher = request.getRequestDispatcher(newUrl);
        dispatcher.forward(request, response);
    } else {
        filterChain.doFilter(request, response);
    }
}

private boolean isLocale(String locale) {
    //validate the string here against an accepted list of locales or whatever
    try {
        LocaleUtils.toLocale(locale);
        return true;
    } catch (IllegalArgumentException e) {
        LOG.trace("Variable \'{}\' is not a Locale", locale);
    }
    return false;
}
}

拦截器与LocaleChangeInterceptor它非常相似,它试图从请求属性中获取区域设置,如果找到了区域设置,则将其设置为LocaleResolver.

public class LocaleAttributeChangeInterceptor extends HandlerInterceptorAdapter {
public static final String LOCALE_ATTRIBUTE_NAME = LocaleAttributeChangeInterceptor.class.getName() + ".LOCALE";

@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) {

    Object newLocale = request.getAttribute(LOCALE_ATTRIBUTE_NAME);
    if (newLocale != null) {
        LocaleResolver localeResolver = RequestContextUtils.getLocaleResolver(request);
        if (localeResolver == null) {
            throw new IllegalStateException("No LocaleResolver found: not in a DispatcherServlet request?");
        }
        localeResolver.setLocale(request, response, StringUtils.parseLocaleString(newLocale.toString()));
    }
    // Proceed in any case.
    return true;
}
}

一旦你有它们就需要配置Spring来使用拦截器和a LocaleResolver.

@Override
public void addInterceptors(InterceptorRegistry registry) {
    registry.addInterceptor(new LocaleAttributeChangeInterceptor());
}

@Bean(name = "localeResolver")
public LocaleResolver getLocaleResolver() {
    return new CookieLocaleResolver();
}

并将过滤器添加到AbstractAnnotationConfigDispatcherServletInitializer.

@Override
protected Filter[] getServletFilters() {
    return new Filter[] { new PathVariableLocaleFilter() };
}

我没有彻底测试它,但它似乎工作到目前为止,你不必触摸你的控制器接受{locale}路径变量,它应该只是开箱即用.也许在未来我们将'locale作为路径变量/子文件夹'Spring自动解决方案,因为越来越多的网站正在采用它,并根据一些它的方式去.

Answer 2

我发现自己也遇到了同样的问题，经过大量研究，我终于设法使用过滤器和LocaleResolver做到了。步骤指南的步骤：

首先在web.xml中设置过滤器：

<filter>
    <filter-name>LocaleFilter</filter-name>
    <filter-class>yourCompleteRouteToTheFilter.LocaleUrlFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>LocaleFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

在LocaleUrlFilter.java中，我们使用正则表达式执行以下操作：

• 在我们稍后将在LocaleResolver上捕获的请求中添加两个属性（国家代码和语言代码）：

• 从网址中剥离语言

  import java.io.IOException;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import javax.servlet.Filter;
  import javax.servlet.FilterChain;
  import javax.servlet.FilterConfig;
  import javax.servlet.ServletException;
  import javax.servlet.ServletRequest;
  import javax.servlet.ServletResponse;
  import javax.servlet.http.HttpServletRequest;
  
  public class LocaleUrlFilter implements Filter{
  
      private static final Pattern localePattern = Pattern.compile("^/([a-z]{2})(?:/([a-z]{2}))?(/.*)?");
      public static final String COUNTRY_CODE_ATTRIBUTE_NAME = LocaleUrlFilter.class.getName() + ".country";
      public static final String LANGUAGE_CODE_ATTRIBUTE_NAME = LocaleUrlFilter.class.getName() + ".language";
  
      @Override
      public void init(FilterConfig arg0) throws ServletException {}  
  
      @Override
      public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
          HttpServletRequest request = (HttpServletRequest) servletRequest;
          String url = request.getRequestURI().substring(request.getContextPath().length());
          Matcher matcher = localePattern.matcher(url);
          if (matcher.matches()) {
              // Set the language attributes that we will use in LocaleResolver and strip the language from the url
              request.setAttribute(COUNTRY_CODE_ATTRIBUTE_NAME, matcher.group(1));
              request.setAttribute(LANGUAGE_CODE_ATTRIBUTE_NAME, matcher.group(2));
              request.getRequestDispatcher(matcher.group(3) == null ? "/" : matcher.group(3)).forward(servletRequest, servletResponse);
          }
          else filterChain.doFilter(servletRequest, servletResponse);     
      }
  
      @Override
      public void destroy() {}
  }
  

现在，过滤器为请求注入了两个属性，我们将使用它们来形成区域设置，并从url中剥离语言以正确处理我们的请求。现在，我们将定义一个LocaleResolver来更改语言环境。首先，我们修改servlet.xml文件：

<!-- locale Resolver configuration-->
<bean id="localeResolver" class="yourCompleteRouteToTheResolver.CustomLocaleResolver"></bean>

然后在CustomLocaleResolver.java中，相应地设置语言。如果url中没有Language，则使用请求的getLocale方法进行操作：

import java.util.Locale;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.web.servlet.LocaleResolver;

/*
* Set the Locale defined in the LocaleUrlFiltes. If none is defined (in the url) return the request locale.
*/
public class CustomLocaleResolver implements LocaleResolver{

    @Override
    public Locale resolveLocale(HttpServletRequest servletRequest) {
        final String countryCode = (String)servletRequest.getAttribute(LocaleUrlFilter.COUNTRY_CODE_ATTRIBUTE_NAME);
        if (countryCode != null) {
            String languageCode = (String)servletRequest.getAttribute(LocaleUrlFilter.LANGUAGE_CODE_ATTRIBUTE_NAME);
            if (languageCode == null) {
                return new Locale(countryCode);
            }
            return new Locale(languageCode, countryCode);
        }
        return servletRequest.getLocale();
    }

    @Override
    public void setLocale(final HttpServletRequest servletRequest, final HttpServletResponse servletResponse, final Locale locale) {
        throw new UnsupportedOperationException();
    }

}

这样做无需更改控制器中的任何内容，访问“ / en / home”将与访问“ / home”并使用language_en.properties文件相同。希望能帮助到你

Answer 3

我最近遇到了同样的问题。因此，我希望拥有不依赖于会话或 cookie 或仅依赖于 URL 的其他任何东西的无状态语言环境。

我尝试了之前答案中建议的过滤器/拦截器/localeResolver 解决方案，但是这些解决方案并不适合我的需求：

• 静态内容（图像等）
• 页面的部分不依赖于语言环境（管理面板）
• 同一应用程序中的 RestController
• 多部分文件上传器

由于 SEO 原因，我还想避免重复内容（特别是我不希望我的英文内容可以从两个路径访问：/landingPage 和 /en/landingPage）。

最适合我的解决方案是创建 LanguageAwareController，然后在我想要支持多种语言环境的所有控制器中继承它。

@Controller
@RequestMapping(path = "/{lang}")
public class LanguageAwareController {
    @Autowired
    LocaleResolver localeResolver;

    @ModelAttribute(name = "locale")
    Locale getLocale(@PathVariable(name = "lang") String lang, HttpServletRequest request,
                 HttpServletResponse response){
        Locale effectiveLocale = Arrays.stream(Locale.getAvailableLocales())
            .filter(locale -> locale.getLanguage().equals(lang))
            .findFirst()
            .orElseGet(Locale::getDefault);
        localeResolver.setLocale(request, response, effectiveLocale);
        return effectiveLocale;
    }
}

在控制器之一中的用法：

@Controller
public class LandingPageController extends LanguageAwareController{

    private Log log = LogFactory.getLog(LandingPageController.class);

    @GetMapping("/")
    public String welcomePage(Locale locale, @PathVariable(name = "lang") String lang ){
        log.info(lang);
        log.info(locale);
        return "landing";
    }
}

Answer 4

在 spring 3.0 中，您可以告诉控制器查找路径变量。例如

@RequestMapping("/{locale}/action")
public void action(@PathVariable String locale) {
    ...
}