9、SpringBoot-CRUD国际化

1）、编写国际化配置文件；

2）、使用ResourceBundleMessageSource管理国际化资源文件

3）、在页面使用fmt:message取出国际化内容

步骤：

1）、编写国际化配置文件，抽取页面需要显示的国际化

文件内容：

2）、使用thymeleaf的语法去引用（jsp是fmt）

<form class="form-signin" action="dashboard.html">
   <img class="mb-4" src="asserts/img/bootstrap-solid.svg" alt="" width="" height="">
   <h1 class="h3 mb-3 font-weight-normal" th:text="#{index_top}">Please sign in</h1>
   <label class="sr-only">Username</label>
   <input type="text" class="form-control" th:placeholder="#{index_Username}" placeholder="Username" required="" autofocus="">
   <label class="sr-only">Password</label>
   <input type="password" class="form-control" th:placeholder="#{index_password}" placeholder="Password" required="">
   <div class="checkbox mb-3">
      <label>
        <input type="checkbox" value="remember-me"> [[#{index_rember}]]
      </label>
   </div>
   <button class="btn btn-lg btn-primary btn-block" type="submit">Sign in</button>
   <p class="mt-5 mb-3 text-muted">© -</p>
   <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>
</form>

效果是根据浏览器的语言设置进行国际化的显示

3）运行查看

系统为英文

系统语言选择中文：

 

SpringBoot自动配置好了管理国际化资源文件的组件

@Configuration
@ConditionalOnMissingBean(
    value = {MessageSource.class},
    search = SearchStrategy.CURRENT
)
@AutoConfigureOrder(-)
@Conditional({MessageSourceAutoConfiguration.ResourceBundleCondition.class})
@EnableConfigurationProperties
public class MessageSourceAutoConfiguration {
    private static final Resource[] NO_RESOURCES = new Resource[];

    public MessageSourceAutoConfiguration() {
    }

    @Bean
    @ConfigurationProperties(
        prefix = "spring.messages"
    )
    public MessageSourceProperties messageSourceProperties() {
        return new MessageSourceProperties();
    }

    @Bean
    public MessageSource messageSource(MessageSourceProperties properties) {
        //管理国际化的
        ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource();
        if (StringUtils.hasText(properties.getBasename())) {
            ////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(properties.getBasename())));
        }

        if (properties.getEncoding() != null) {
            messageSource.setDefaultEncoding(properties.getEncoding().name());
        }

        messageSource.setFallbackToSystemLocale(properties.isFallbackToSystemLocale());
        Duration cacheDuration = properties.getCacheDuration();
        if (cacheDuration != null) {
            messageSource.setCacheMillis(cacheDuration.toMillis());
        }

        messageSource.setAlwaysUseMessageFormat(properties.isAlwaysUseMessageFormat());
        messageSource.setUseCodeAsDefaultMessage(properties.isUseCodeAsDefaultMessage());
        return messageSource;
    }

    protected static class ResourceBundleCondition extends SpringBootCondition {
        private static ConcurrentReferenceHashMap<String, ConditionOutcome> cache = new ConcurrentReferenceHashMap();

        protected ResourceBundleCondition() {
        }

        public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
            ////我们的配置文件可以直接放在类路径下叫messages.properties
            String basename = context.getEnvironment().getProperty("spring.messages.basename", "messages");
            ConditionOutcome outcome = (ConditionOutcome)cache.get(basename);
            if (outcome == null) {
                outcome = this.getMatchOutcomeForBasename(context, basename);
                cache.put(basename, outcome);
            }

            return outcome;
        }

        private ConditionOutcome getMatchOutcomeForBasename(ConditionContext context, String basename) {
            Builder message = ConditionMessage.forCondition("ResourceBundle", new Object[]);
            String[] var4 = StringUtils.commaDelimitedListToStringArray(StringUtils.trimAllWhitespace(basename));
            int var5 = var4.length;

            for(int var6 = ; var6 < var5; ++var6) {
                String name = var4[var6];
                Resource[] var8 = this.getResources(context.getClassLoader(), name);
                int var9 = var8.length;

                for(int var10 = ; var10 < var9; ++var10) {
                    Resource resource = var8[var10];
                    if (resource.exists()) {
                        return ConditionOutcome.match(message.found("bundle").items(new Object[]{resource}));
                    }
                }
            }
            return ConditionOutcome.noMatch(message.didNotFind("bundle with basename " + basename).atAll());
        }
        private Resource[] getResources(ClassLoader classLoader, String name) {
            String target = name.replace('.', '/');

            try {
                return (new PathMatchingResourcePatternResolver(classLoader)).getResources("classpath*:" + target + ".properties");
            } catch (Exception var5) {
                return MessageSourceAutoConfiguration.NO_RESOURCES;
            }
        }
    }
}

容器中没有就使用默认的

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

原理：

国际化的Local（区域信息对象）；LocalResolver（获取区域信息对象）

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[],split[]);
        }
        return locale;
    }
    @Override
    public void setLocale(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Locale locale) {
        resolveLocale(httpServletRequest);
    }
} 

加入容器

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

值得一说的是

@Bean()
public LocaleResolver localeResolver(){
    return  new MyLocaleResolver();
}

LocaleResolver 如果后面不跟localeResolver的话  就需在@Bean指定name

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