springboot支持国际化
Spring Boot支持本地化的消息，这样你的应用程序就可以满足不同语言偏好的用户。 默认情况下，Spring Boot会在classpath的根部寻找 messages 资源包（resource bundle）的存在。
自动配置只有在资源包中存在默认的properties文件（默认为 messages.properties ）时才生效。如果资源包中只有特定语言的properties，那你需要添加默认的。 没有没有找到任何base name和语言相匹配的文件，MessageSource 不会自动配置。
在application.properties加上如下配置
spring.messages.basename=messages,config.i18n.messages
spring.messages.fallback-to-system-locale=false// Steps:
// --Understand Locale(know language codes)
// --Configure Locale resolver and interceptor in spring
// -- Create languge files(messages_XX.properties) messages.properties:default
// -- Update Thymeleaf views for i18n Print text:[[#{key}]] Attribute:th:value="#{key}"
// -- Switch between languages(Englich,Chinese..) URL paramter:?lang=xx1.获取语言对应的code
@GetMapping("/")
public String hello( HttpServletRequest request) {
// 修改语言是在浏览器上修改，比如谷歌 设置 语言
Locale currentLocal = request.getLocale();
String countryCode = currentLocal.getCountry();
String countryName = currentLocal.getDisplayCountry();
String langCode = currentLocal.getLanguage();
String langName = currentLocal.getDisplayLanguage();
System.out.println(countryCode + ":" + countryName);
System.out.println(langCode + ":" + langName);
System.out.println("==========================");
String[] languages = Locale.getISOLanguages();
for (String language : languages) {
Locale locale = new Locale(language);
// de:德语 en:英语 zh:中文
// System.out.println(language+":"+locale.getDisplayLanguage());
}
return "hello";
}
2.配置如下代码
package com.integration.scaffold.javai18n;
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.WebMvcConfigurer;
import org.springframework.web.servlet.i18n.LocaleChangeInterceptor;
import org.springframework.web.servlet.i18n.SessionLocaleResolver;
import java.util.Locale;
import java.util.TimeZone;
@Configuration
public class MultiLanguageConfig implements WebMvcConfigurer {
@Bean
public LocaleResolver localeResolver() {
SessionLocaleResolver slr = new SessionLocaleResolver();
slr.setDefaultLocale(Locale.US);
// timezone to change datetime output
slr.setDefaultTimeZone(TimeZone.getTimeZone("UTC"));
return slr;
}
@Bean
public LocaleChangeInterceptor localeChangeInterceptor() {
LocaleChangeInterceptor lci = new LocaleChangeInterceptor();
lci.setParamName("lang");
return lci;
}
@Override
public void addInterceptors(InterceptorRegistry registry) {
registry.addInterceptor(localeChangeInterceptor());
}
}3.创建messages_xx.properties文件 如下示例代码
hello.title=New day, new weather
hello=Hello!
welcome=Welcome to my app
switch-en=Switch to English
switch-zh=Switch to Chinese
hello.title=新的一天新气象
hello=你好
welcome=欢迎来到APP
switch-en=切换到英语
switch-zh=切换到中文 
4.写一个Thymeleaf,格式为：
text:[[#{key}]] Attribute:th:value="#{key}"<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title th:text="#{welcome}"></title>
</head>
<body>
<div>
<h1>[[#{hello.title}]]</h1>
</div>
<span th:text="#{hello}"></span><br>
<span th:text="#{welcome}"></span><br>
<button type="button" th:text="#{switch-en}"
onclick="window.location.href='http://localhost:8080/Scaffold/?lang=en'"></button>
<button type="button" th:text="#{switch-zh}"
onclick="window.location.href='http://localhost:8080/Scaffold/?lang=zh'"></button>
</body>
</html>在浏览器输入地址，既可以切换语言了
点击切换到中文
再点击切换到英文就可以切换到英文了
好了，国际化就做好了！
