SpringBoot下资源国际化应用实践

@Configuration
@ConditionalOnMissingBean(value = MessageSource.class, search = SearchStrategy.CURRENT)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Conditional(ResourceBundleCondition.class)
@EnableConfigurationProperties
@ConfigurationProperties(prefix = "spring.messages")
public class MessageSourceAutoConfiguration {
  private static final Resource[] NO_RESOURCES = {};
  /**
   * Comma-separated list of basenames (essentially a fully-qualified classpath
   * location), each following the ResourceBundle convention with relaxed support for
   * slash based locations. If it doesn't contain a package qualifier (such as
   * "org.mypackage"), it will be resolved from the classpath root.
   */
  private String basename = "messages";
  //我们的配置文件可以直接放在类路径下叫messages.properties；
  /**
   * Message bundles encoding.
   */
  private Charset encoding = Charset.forName("UTF-8");
  /**
   * Loaded resource bundle files cache expiration, in seconds. When set to -1, bundles
   * are cached forever.
   */
  private int cacheSeconds = -1;
  /**
   * Set whether to fall back to the system Locale if no files for a specific Locale
   * have been found. if this is turned off, the only fallback will be the default file
   * (e.g. "messages.properties" for basename "messages").
   */
  private boolean fallbackToSystemLocale = true;
  /**
   * Set whether to always apply the MessageFormat rules, parsing even messages without
   * arguments.
   */
  private boolean alwaysUseMessageFormat = false;
  //为容器添加了ResourceBundleMessageSource 组件
  @Bean
  public MessageSource messageSource() {
    ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
    if (StringUtils.hasText(this.basename)) {
      //设置国际化资源文件的基础名（去掉语言国家代码的）
      messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray(
          StringUtils.trimAllWhitespace(this.basename)));
    }
    if (this.encoding != null) {
      messageSource.setDefaultEncoding(this.encoding.name());
    }
    messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale);
    messageSource.setCacheSeconds(this.cacheSeconds);
    messageSource.setAlwaysUseMessageFormat(this.alwaysUseMessageFormat);
    return messageSource;
  }

# 国际化配置文件（包名.基础名）
spring.messages.basename=i18n.login

<label class="sr-only" th:text="#{login.username}">Username</label>
<input type="text"  name="username" class="form-control" placeholder="Username" th:placeholder="#{login.username}" required="" autofocus="">
<label class="sr-only" th:text="#{login.password}">Password</label>
<input type="password" name="password" class="form-control" placeholder="Password" th:placeholder="#{login.password}" required="">
<div class="checkbox mb-3">
<label>
<input type="checkbox" value="remember-me"/> [[#{login.remember}]]
//这里使用行内写法，input是自结束标签，没有标签体
</label>
</div>
<button class="btn btn-lg btn-primary btn-block" type="submit" th:text="#{login.btn}">Sign in</button>

@Bean
@ConditionalOnMissingBean
@ConditionalOnProperty(prefix = "spring.mvc", name = "locale")
public LocaleResolver localeResolver() {
  if (this.mvcProperties
      .getLocaleResolver() == WebMvcProperties.LocaleResolver.FIXED) {
    return new FixedLocaleResolver(this.mvcProperties.getLocale());
  }
  AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
  localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
  return localeResolver;
}

<a class="btn btn-sm" th:href="@{/index.html(l='zh_CN')}">中文</a>
<a class="btn btn-sm" th:href="@{/index.html(l='en_US')}">English</a>

<a class="btn btn-sm" th:href="@{/index.html?l=zh_CN}">中文</a>
<a class="btn btn-sm" th:href="@{/index.html?l=en_US}">English</a>

/**
 * 可以在连接上携带区域信息
 */
public class MyLocaleResolver implements LocaleResolver {
    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        String l = request.getParameter("l");
        Locale locale = Locale.getDefault();
        if(!StringUtils.isEmpty(l)){
            String[] split = l.split("_");
            locale = new Locale(split[0],split[1]);
        }
        return locale;
    }
    @Override
    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
    }
}

@Configuration
public class MyMvcConfig extends WebMvcConfigurerAdapter {
  @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }
}