SpringBoot实现国际化

在哔哩哔哩一位up主视频中学到的！

国际化

原理

通过Properties文件配置，配置完后通过Thymeleaf中的#{} 来取代原来的静态资源。例如：

spring:
  # 关闭模板引擎的缓存
  thymeleaf:
    cache: false
  messages:
    encoding: UTF-8
    ## 配置国际化绑定的文件 不绑定会乱码
    basename: i18n.login

语言环境解析器接口

package org.springframework.web.servlet;

import java.util.Locale;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.lang.Nullable;

public interface LocaleResolver {
    //解析语言环境
    Locale resolveLocale(HttpServletRequest var1);

    void setLocale(HttpServletRequest var1, @Nullable HttpServletResponse var2, @Nullable Locale var3);
}

在SpringMvc自动配置类中语言环境解析器代码如下

public class WebMvcAutoConfiguration {
    //**语言环境解析器**
    public LocaleResolver localeResolver() {
        if (this.mvcProperties.getLocaleResolver() == org.springframework.boot.autoconfigure.web.servlet.WebMvcProperties.LocaleResolver.FIXED) {
            return new FixedLocaleResolver(this.mvcProperties.getLocale());
        } else { 
            //  AcceptHeaderLocaleResolver 默认的**语言环境解析器**
            AcceptHeaderLocaleResolver localeResolver = new AcceptHeaderLocaleResolver();
            localeResolver.setDefaultLocale(this.mvcProperties.getLocale());
            return localeResolver;
        }
    }
}

默认使用的语言环境解析器

package org.springframework.web.servlet.i18n;

import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.LocaleResolver;

public class AcceptHeaderLocaleResolver implements LocaleResolver {
    private final List<Locale> supportedLocales = new ArrayList(4);
    @Nullable
    private Locale defaultLocale;

    public AcceptHeaderLocaleResolver() {
    }

    public void setSupportedLocales(List<Locale> locales) {
        this.supportedLocales.clear();
        this.supportedLocales.addAll(locales);
    }

    public List<Locale> getSupportedLocales() {
        return this.supportedLocales;
    }

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

    @Nullable
    public Locale getDefaultLocale() {
        return this.defaultLocale;
    }
	//!!!
    public Locale resolveLocale(HttpServletRequest request) {
        Locale defaultLocale = this.getDefaultLocale();
        if (defaultLocale != null && request.getHeader("Accept-Language") == null) {
            return defaultLocale;
        } else {
            Locale requestLocale = request.getLocale();
            List<Locale> supportedLocales = this.getSupportedLocales();
            if (!supportedLocales.isEmpty() && !supportedLocales.contains(requestLocale)) {
                Locale supportedLocale = this.findSupportedLocale(request, supportedLocales);
                if (supportedLocale != null) {
                    return supportedLocale;
                } else {
                    return defaultLocale != null ? defaultLocale : requestLocale;
                }
            } else {
                return requestLocale;
            }
        }
    }

    @Nullable
    private Locale findSupportedLocale(HttpServletRequest request, List<Locale> supportedLocales) {
        Enumeration<Locale> requestLocales = request.getLocales();
        Locale languageMatch = null;

        Locale locale;
        label38:
        do {
            while(requestLocales.hasMoreElements()) {
                locale = (Locale)requestLocales.nextElement();
                if (supportedLocales.contains(locale)) {
                    continue label38;
                }

                if (languageMatch == null) {
                    Iterator var6 = supportedLocales.iterator();

                    while(var6.hasNext()) {
                        Locale candidate = (Locale)var6.next();
                        if (!StringUtils.hasLength(candidate.getCountry()) && candidate.getLanguage().equals(locale.getLanguage())) {
                            languageMatch = candidate;
                            break;
                        }
                    }
                }
            }

            return languageMatch;
        } while(languageMatch != null && !languageMatch.getLanguage().equals(locale.getLanguage()));

        return locale;
    }
	//!!!
    public void setLocale(HttpServletRequest request, @Nullable HttpServletResponse response, @Nullable Locale locale) {
        throw new UnsupportedOperationException("Cannot change HTTP accept header - use a different locale resolution strategy");
    }
}

自定义语言环境解析器

我们自定义语言环境解析器，然后在引入到WebMvc配置类中，来替代原有的语言环境解析器。

我们只需要实现LocaleResolver接口即可

/**
 * 自定义 语言环境解析器
 */
public class MyLocaleResolver implements LocaleResolver {
  //解析请求
    @Override
    public Locale resolveLocale(HttpServletRequest httpServletRequest) {
        //获取请求中的语言参数
        Locale locale = null;
        final String language = httpServletRequest.getParameter("Language"); //例如 zh_CN  en_US
        System.out.println("------->"+language);
        if(!StringUtils.isEmpty(language)){ // return target == null || target.length() == 0;
            final String[] s = language.split("_");
            // s[0]:国家 s[1]:地区
            locale = new Locale(s[0],s[1]);
            return locale;
        }
        locale = Locale.getDefault(); // 如果没有请求参数就是默认的
        return locale;
    }

    @Override
    public void setLocale(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Locale locale) {

    }
}

将自定义的语言环境解析器，加入SpringMvc自动配置类中

在自动配置类中需要将自定义的MyLocaleResolver类取代WebMvcAutoConfiguration中对应的方法

/**
 * 定义一个WebMvcConfigurer 的实现类，可以重写SpringMvc的配置
 * 在这个类中 定义的组件，然后将它交给springboot，springboot就会自动装配
 */
@Configuration
public class MyMvcConfig implements WebMvcConfigurer {

    //自定义国际化组件  重写了 WebMvcAutoConfiguration 类中的  localeResolver 方法 
    @Bean
    public LocaleResolver localeResolver(){
        return new MyLocaleResolver();
    }

}

效果图展示