如何在Spring boot 2 Webflux Thymelaf中配置i18n？

Question

我刚刚开始了一个基于Spring机2的新项目。在升级Spring启动版本时，将sping-boot-starter-web替换为sping-boot-starter-web的类，例如

• WebMvcConfigurerAdapter
• 区域设置解析程序
• LocaleChangeInterceptor

缺少。现在如何配置defaultLocale和拦截器以更改语言？




Answer 1

从 Spring Boot 2.4.0 开始，WebFluxAutoConfiguration 包含一个 LocaleContextResolver 的 bean 定义，它允许我们注入自定义 LocaleContextResolver。作为参考，以下是 Spring Boot 2.5.4 中的默认 Bean 定义（在早期版本中实现可能有所不同）：

@Bean
@Override
@ConditionalOnMissingBean(name = WebHttpHandlerBuilder.LOCALE_CONTEXT_RESOLVER_BEAN_NAME)
public LocaleContextResolver localeContextResolver() {
    if (this.webProperties.getLocaleResolver() == WebProperties.LocaleResolver.FIXED) {
        return new FixedLocaleContextResolver(this.webProperties.getLocale());
    }
    AcceptHeaderLocaleContextResolver localeContextResolver = new AcceptHeaderLocaleContextResolver();
    localeContextResolver.setDefaultLocale(this.webProperties.getLocale());
    return localeContextResolver;
}

您可以通过提供自定义 Bean 定义来提供自己的 LocaleContextResolver 实现，以便从查询参数中获取语言环境：

//@Component("localeContextResolver")
@Component(WebHttpHandlerBuilder.LOCALE_CONTEXT_RESOLVER_BEAN_NAME)
public class RequestParamLocaleContextResolver implements LocaleContextResolver {
    @Override
    public LocaleContext resolveLocaleContext(ServerWebExchange exchange) {
        List<String> lang = exchange.getRequest().getQueryParams().get("lang");
        Locale targetLocale = null;
        if (lang != null && !lang.isEmpty()) {
            targetLocale = Locale.forLanguageTag(lang.get(0));
        }
        if (targetLocale == null) {
            targetLocale = Locale.getDefault();
        }
        return new SimpleLocaleContext(targetLocale);
    }

    @Override
    public void setLocaleContext(ServerWebExchange exchange, LocaleContext localeContext) {
        throw new UnsupportedOperationException(
            "Cannot change lang query parameter - use a different locale context resolution strategy");
    }
}

请注意，框架使用带有特定名称localeContextResolver的localeContextResolver（WebHttpHandlerBuilder.LOCALE_CONTEXT_RESOLVER_BEAN_NAME）。您需要提供具有给定名称的bean。请参见#24209。

Answer 2

匿名用户

有了Spring引导启动器网络通量，有

< li >委托WebFluxConfiguration < li>LocaleContextResolver

例如，要使用查询参数“lang”显式控制语言环境：

> < li>

实现< code > LocaleContextResolver ，以便< code > resolveLocaleContext()返回由GET参数“lang”确定的< code>SimpleLocaleContext。我将这个实现命名为< code > queryparamloclecontextresolver 。请注意，默认的< code > LocaleContextResolver 是一个< code > org . spring framework . web . server . i18n . acceptheaderlocalecontextresolver 。

创建一个@配置类，该类扩展了委托WebF配置。覆盖DelegatingWebFluxConfiguration.localeContextResolver（）以返回我们刚刚在步骤1中创建的QueryParamLocaleContextResolver。将此配置类命名为WebConfig。

在 WebConfig 中，覆盖 DedelegateatingWebFluxConfiguration.configureViewResolvers（） 并将 ThymeleafReactiveViewResolver bean 添加为视图解析器。我们这样做是因为，由于某种原因，委派WebFluxConfiguration将在步骤2之后错过ThymeleafReactiveViewResolver。

另外，我必须提到，要将 i18n 与反应式堆栈一起使用，这个 bean 是必要的：

    @Bean
    public MessageSource messageSource() {
        final ReloadableResourceBundleMessageSource messageSource = new ReloadableResourceBundleMessageSource();
        messageSource.setBasenames("classpath:/messages");
        messageSource.setUseCodeAsDefaultMessage(true);
        messageSource.setDefaultEncoding("UTF-8");
        messageSource.setCacheSeconds(5);
        return messageSource;
}

创建自然模板、一些属性文件和控制器后，您将看到：

>

localhost:8080/test?lang=zh给你中文版

< code >本地主机:8080/test？lang=en为您提供英文版

只是不要忘记<代码>

Answer 3

只需添加一个 WebFilter，该筛选器根据查询参数的值设置接受语言标头。以下示例从 URI 上的语言查询参数（如 http://localhost:8080/examples?language=es）中获取语言：

import org.springframework.boot.context.event.ApplicationReadyEvent;
import org.springframework.context.ApplicationContext;
import org.springframework.context.event.EventListener;
import org.springframework.http.server.reactive.ServerHttpRequest;
import org.springframework.stereotype.Component;
import org.springframework.util.MultiValueMap;
import org.springframework.web.server.ServerWebExchange;
import org.springframework.web.server.WebFilter;
import org.springframework.web.server.WebFilterChain;
import org.springframework.web.server.adapter.DefaultServerWebExchange;
import org.springframework.web.server.adapter.HttpWebHandlerAdapter;
import reactor.core.publisher.Mono;

import static org.springframework.util.StringUtils.isEmpty;

@Component
public class LanguageQueryParameterWebFilter implements WebFilter {

    private final ApplicationContext applicationContext;

    private HttpWebHandlerAdapter httpWebHandlerAdapter;

    public LanguageQueryParameterWebFilter(final ApplicationContext applicationContext) {
        this.applicationContext = applicationContext;
    }

    @EventListener(ApplicationReadyEvent.class)
    public void loadHttpHandler() {
        this.httpWebHandlerAdapter = applicationContext.getBean(HttpWebHandlerAdapter.class);
    }

    @Override
    public Mono<Void> filter(final ServerWebExchange exchange, final WebFilterChain chain) {
        final ServerHttpRequest request = exchange.getRequest();
        final MultiValueMap<String, String> queryParams = request.getQueryParams();
        final String languageValue = queryParams.getFirst("language");

        final ServerWebExchange localizedExchange = getServerWebExchange(languageValue, exchange);
        return chain.filter(localizedExchange);
    }

    private ServerWebExchange getServerWebExchange(final String languageValue, final ServerWebExchange exchange) {
        return isEmpty(languageValue)
                ? exchange
                : getLocalizedServerWebExchange(languageValue, exchange);
    }

    private ServerWebExchange getLocalizedServerWebExchange(final String languageValue, final ServerWebExchange exchange) {
        final ServerHttpRequest httpRequest = exchange.getRequest()
                .mutate()
                .headers(httpHeaders -> httpHeaders.set("Accept-Language", languageValue))
                .build();

        return new DefaultServerWebExchange(httpRequest, exchange.getResponse(),
                httpWebHandlerAdapter.getSessionManager(), httpWebHandlerAdapter.getCodecConfigurer(),
                httpWebHandlerAdapter.getLocaleContextResolver());
    }
}

它使用 @EventListener（ApplicationReadyEvent.class） 来避免循环依赖。

请随时测试并提供有关POC的反馈。