SpringBoot系列之i18n集成教程

2019-11-25 来源: smileNicky 发布在  https://www.cnblogs.com/mzq123/p/11925325.html

SpringBoot系统之i18n国际化语言集成教程
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1、环境搭建

本博客介绍一下SpringBoot集成i18n,实现系统语言国际化处理,ok,先创建一个SpringBoot项目,具体的参考我的博客专栏:SpringBoot系列博客专栏链接

环境准备:

  • IntelliJ IDEA
  • Maven

项目集成:

  • Thymeleaf(模板引擎,也可以选jsp或者freemark)
  • SpringBoot2.2.1.RELEASE

2、resource bundle资源配置

ok,要实现国际化语言,先要创建resource bundle文件:
在resources文件夹下面创建一个i18n的文件夹,其中:

  • messages.properties是默认的配置
  • messages_zh_CN.properties是(中文/中国)
  • messages_en_US.properties是(英文/美国)
  • etc.

    IDEA工具就提供了很简便的自动配置功能,如图,只要点击新增按钮,手动输入,各配置文件都会自动生成属性

    messages.properties:
messages.loginBtnName=登录~
messages.password=密码~
messages.rememberMe=记住我~
messages.tip=请登录~
messages.username=用户名~

messages_zh_CN.properties:

messages.loginBtnName=登录
messages.password=密码
messages.rememberMe=记住我
messages.tip=请登录
messages.username=用户名

messages_en_US.properties:

messages.loginBtnName=login
messages.password=password
messages.rememberMe=Remember me
messages.tip=Please login in
messages.username=userName

在项目的application.properties修改默认配置,让SpringBoot的自动配置能读取到resource bundle资源文件

## 配置i18n
# 默认是i18n(中文/中国)
spring.mvc.locale=zh_CN
# 配置resource bundle资源文件的前缀名eg:i18n是文件夹名,messages是资源文件名,支持的符号有.号或者/
spring.messages.basename=i18n.messages
# 设置缓存时间,2.2.1是s为单位,之前版本才是毫秒
spring.messages.cache-duration=1
# 设置资源文件编码格式为utf8
spring.messages.encoding=utf-8

注意要点:

  • spring.messages.basename必须配置,否则SpringBoot的自动配置将失效
    MessageSourceAutoConfiguration.ResourceBundleCondition 源码:
protected static class ResourceBundleCondition extends SpringBootCondition {
        //定义一个map缓存池
        private static ConcurrentReferenceHashMap<String, ConditionOutcome> cache = new ConcurrentReferenceHashMap<>();

        @Override
        public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
            String basename = context.getEnvironment().getProperty("spring.messages.basename", "messages");
            ConditionOutcome outcome = cache.get(basename);//缓存拿得到,直接从缓存池读取
            if (outcome == null) {//缓存拿不到,重新读取
                outcome = getMatchOutcomeForBasename(context, basename);
                cache.put(basename, outcome);
            }
            return outcome;
        }

        private ConditionOutcome getMatchOutcomeForBasename(ConditionContext context, String basename) {
            ConditionMessage.Builder message = ConditionMessage.forCondition("ResourceBundle");
            for (String name : StringUtils.commaDelimitedListToStringArray(StringUtils.trimAllWhitespace(basename))) {
                for (Resource resource : getResources(context.getClassLoader(), name)) {
                    if (resource.exists()) {
                    //匹配resource bundle资源
                        return ConditionOutcome.match(message.found("bundle").items(resource));
                    }
                }
            }
            return ConditionOutcome.noMatch(message.didNotFind("bundle with basename " + basename).atAll());
        }
        //解析资源文件
        private Resource[] getResources(ClassLoader classLoader, String name) {
            String target = name.replace('.', '/');//spring.messages.basename参数值的点号换成斜杆
            try {
                return new PathMatchingResourcePatternResolver(classLoader)
                        .getResources("classpath*:" + target + ".properties");
            }
            catch (Exception ex) {
                return NO_RESOURCES;
            }
        }

    }
  • cache-duration在2.2.1版本,指定的是s为单位,找到SpringBoot的MessageSourceAutoConfiguration自动配置类

3、LocaleResolver类

SpringBoot默认采用AcceptHeaderLocaleResolver类作为默认LocaleResolver,LocaleResolver类的作用就是作为i18n的分析器,获取对应的i18n配置,当然也可以自定义LocaleResolver类


import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.LocaleResolver;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.util.Locale;

/**
 * <pre>
 *  自定义LocaleResolver类
 * </pre>
 * @author nicky
 * <pre>
 * 修改记录
 *    修改后版本:     修改人:  修改日期: 2019年11月23日  修改内容:
 * </pre>
 */
public class CustomLocalResolver implements LocaleResolver {

    Logger LOG = LoggerFactory.getLogger(this.getClass());

    @Nullable
    private Locale defaultLocale;

    public void setDefaultLocale(@Nullable Locale defaultLocale) {
        this.defaultLocale = defaultLocale;
    }

    @Nullable
    public Locale getDefaultLocale() {
        return this.defaultLocale;
    }

    @Override
    public Locale resolveLocale(HttpServletRequest request) {
        Locale defaultLocale = this.getDefaultLocale();//获取application.properties默认的配置
        if(defaultLocale != null && request.getHeader("Accept-Language") == null) {
            return defaultLocale;//http请求头没获取到Accept-Language才采用默认配置
        } else {//request.getHeader("Accept-Language")获取得到的情况
            Locale requestLocale = request.getLocale();//获取request.getHeader("Accept-Language")的值
            String localeFlag = request.getParameter("locale");//从URL获取的locale值
            //LOG.info("localeFlag:{}",localeFlag);
            //url链接有传locale参数的情况,eg:zh_CN
            if (!StringUtils.isEmpty(localeFlag)) {
                String[] split = localeFlag.split("_");
                requestLocale = new Locale(split[0], split[1]);
            }
            //没传的情况,默认返回request.getHeader("Accept-Language")的值
            return requestLocale;
        }
    }

    @Override
    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {

    }
}

4、I18n配置类

I18n还是要继承WebMvcConfigurer,注意,2.2.1版本才是实现接口就可以,之前1.+版本是要实现WebMvcConfigurerAdapter适配器类的

import com.example.springboot.i18n.component.CustomLocalResolver;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.ViewControllerRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;
import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;

/**
 * <pre>
 *  I18nConfig配置类
 * </pre>
 * <p>
 * <pre>
 * @author nicky.ma
 * 修改记录
 *    修改后版本:     修改人:  修改日期: 2019/11/24 11:15  修改内容:
 * </pre>
 */
 //Configuration必须加上,不然不能加载到Spring容器
@Configuration
//使WebMvcProperties配置类可用,这个可以不加上,本博客例子才用
@EnableConfigurationProperties({ WebMvcProperties.class})
public class I18nConfig implements WebMvcConfigurer{

    //装载WebMvcProperties 属性
    @Autowired
    WebMvcProperties webMvcProperties;
    /**
     * 定义SessionLocaleResolver
     * @Author nicky.ma
     * @Date 2019/11/24 13:52
     * @return org.springframework.web.servlet.LocaleResolver
     */
//    @Bean
//    public LocaleResolver localeResolver() {
//        SessionLocaleResolver sessionLocaleResolver = new SessionLocaleResolver();
//        // set default locale
//        sessionLocaleResolver.setDefaultLocale(Locale.US);
//        return sessionLocaleResolver;
//    }

    /**
     * 定义CookieLocaleResolver
     * @Author nicky.ma
     * @Date 2019/11/24 13:51
     * @return org.springframework.web.servlet.LocaleResolver
     */
//    @Bean
//    public LocaleResolver localeResolver() {
//        CookieLocaleResolver cookieLocaleResolver = new CookieLocaleResolver();
//        cookieLocaleResolver.setCookieName("Language");
//        cookieLocaleResolver.setCookieMaxAge(1000);
//        return cookieLocaleResolver;
//    }

    /**
     * 自定义LocalResolver
     * @Author nicky.ma
     * @Date 2019/11/24 13:45
     * @return org.springframework.web.servlet.LocaleResolver
     */
    @Bean
    public LocaleResolver localeResolver(){
        CustomLocalResolver localResolver = new CustomLocalResolver();
        localResolver.setDefaultLocale(webMvcProperties.getLocale());
        return localResolver;
    }

    /**
     * 定义localeChangeInterceptor
     * @Author nicky.ma
     * @Date 2019/11/24 13:45
     * @return org.springframework.web.servlet.i18n.LocaleChangeInterceptor
     */
    @Bean
    public LocaleChangeInterceptor localeChangeInterceptor(){
        LocaleChangeInterceptor localeChangeInterceptor = new LocaleChangeInterceptor();
        //默认的请求参数为locale,eg: login?locale=zh_CN
        localeChangeInterceptor.setParamName(LocaleChangeInterceptor.DEFAULT_PARAM_NAME);
        return localeChangeInterceptor;
    }

    /**
     * 注册拦截器
     * @Author nicky.ma
     * @Date 2019/11/24 13:47
     * @Param [registry]
     * @return void
     */
    @Override
    public void addInterceptors(InterceptorRegistry registry) {
     registry.addInterceptor(localeChangeInterceptor()).addPathPatterns("/**");
    }
}

注意要点:

  • 旧版代码可以不加LocaleChangeInterceptor 拦截器,2.2.1版本必须通过拦截器
  • 如下代码,bean的方法名必须为localeResolver,否则会报错
@Bean
    public LocaleResolver localeResolver(){
        CustomLocalResolver localResolver = new CustomLocalResolver();
        localResolver.setDefaultLocale(webMvcProperties.getLocale());
        return localResolver;
    }

原理:
跟一下源码,点进LocaleChangeInterceptor类


DispatcherServlet是Spring一个很重要的分发器类,在DispatcherServlet的一个init方法里找到这个LocaleResolver的init方法

这个IOC获取的bean类名固定为localeResolver,写例子的时候,我就因为改了bean类名,导致一直报错,跟了源码才知道Bean类名要固定为localeResolver

抛异常的时候,也是会获取默认的LocaleResolver的


找到资源文件,确认,还是默认为AcceptHeaderLocaleResolver

配置了locale属性的时候,还是选用AcceptHeaderLocaleResolver作为默认的LocaleResolver

spring.mvc.locale=zh_CN

WebMvcAutoConfiguration.localeResolver方法源码,ConditionalOnMissingBean主键的意思是LocaleResolver没有自定义的时候,才作用,ConditionalOnProperty的意思,有配了属性才走这里的逻辑

  • 拦截器拦截的请求参数默认为locale,要使用其它参数,必须通过拦截器设置 ,eg:localeChangeInterceptor.setParamName("lang");
  • LocalResolver种类有:CookieLocaleResolver(Cookie)、SessionLocaleResolver(会话)、FixedLocaleResolver、AcceptHeaderLocaleResolver(默认)、.etc

5、Thymeleaf集成

本博客的模板引擎采用Thymeleaf的,所以新增项目时候就要加上maven相关依赖,没有的话,自己加上:

<dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

ok,然后去找个bootstrap的登录页面,本博客已尚硅谷老师的例子为例,进行拓展,引入静态资源文件:

Thymeleaf的i18n支持是采用#符号的

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
        <meta name="description" content="">
        <meta name="author" content="">
        <title>SpringBoot i18n example</title>
        <!-- Bootstrap core CSS -->
        <link href="asserts/css/bootstrap.min.css" th:href="@{asserts/css/bootstrap.min.css}" rel="stylesheet">
        <!-- Custom styles for this template -->
        <link href="asserts/css/signin.css" th:href="@{asserts/css/signin.css}" rel="stylesheet">
    </head>

    <body class="text-center">
        <form class="form-signin" action="dashboard.html">
            <img class="mb-4" th:src="@{asserts/img/bootstrap-solid.svg}" alt="" width="72" height="72">
            <h1 class="h3 mb-3 font-weight-normal" th:text="#{messages.tip}">Please sign in</h1>
            <label class="sr-only" th:text="#{messages.username}">Username</label>
            <input type="text" class="form-control" th:placeholder="#{messages.username}" required="" autofocus="">
            <label class="sr-only" th:text="#{messages.password} ">Password</label>
            <input type="password" class="form-control" th:placeholder="#{messages.password}" required="">
            <div class="checkbox mb-3">
                <label>
          <input type="checkbox" value="remember-me" > [[#{messages.rememberMe}]]
        </label>
            </div>
            <button class="btn btn-lg btn-primary btn-block" type="submit" th:text="#{messages.loginBtnName}">Sign in</button>
            <p class="mt-5 mb-3 text-muted">© 2019</p>
            <a class="btn btn-sm" th:href="@{/login(locale='zh_CN')} ">中文</a>
            <a class="btn btn-sm" th:href="@{/login(locale='en_US')} ">English</a>
        </form>

    </body>

</html>

切换中文网页:

切换英文网页:

当然不点链接传locale的方式也是可以自动切换的,浏览器设置语言:

原理localeResolver类会获取Accept language参数

附录:
logging manual:SpringBoot官方手册
example source:例子代码下载链接

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