springboot+thymeleaf国际化方法一：LocaleResolver

springboot中大部分有默认配置所以开发起项目来非常迅速，仅对需求项做单独配置覆盖即可

spring采用的默认区域解析器是AcceptHeaderLocaleResolver，根据request header中的accept-language值来解析locale，并且是不可变的。

那么想要实现国际化，就要使用SessionLocaleResolver或者CookieLocaleResolver。正如类的名字所示，是按session或cookie中储存的locale值来解析locale。

我就以SessionLocaleResolver举例：

1.建立一个配置类

package com.example.config;

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.support.ResourceBundleMessageSource;
import org.springframework.web.servlet.LocaleResolver;
import org.springframework.web.servlet.i18n.SessionLocaleResolver;

/**
 * Created by wq on 2016/8/15.
 */
@Configuration
public class SpringMVC_config {
    @Bean(name="localeResolver")
    public LocaleResolver localeResolverBean() {
        return new SessionLocaleResolver();
    }
//    @Bean(name="messageSource")
//    public ResourceBundleMessageSource resourceBundleMessageSource(){
//        ResourceBundleMessageSource source=new ResourceBundleMessageSource();
//        source.setBasename("messages");
//        return source;
//    }
}

注意 name="localeResolver" 是必须的

优先级如下：

session中对应属性（3中有说明）有值则按session来

如果没有但是SessionLocaleResolver设置了默认的locale则按默认值来

//        SessionLocaleResolver localeResolver=new SessionLocaleResolver();
//        localeResolver.setDefaultLocale(Locale.ENGLISH);

再然后就还是按request header中的accept-language值来

2.建立对应的messages.properties

messages.properties

messages_en.properties

messages_zh_CN.properties

前面注释的代码则可以修改properties的前缀部分，name="messageSource" 同样是必须的

比如 setBasename("msg"); 对应properties则为

msg.properties

msg_en.properties

msg_zh_CN.properties

格式上sys.test=hello、sys.test=你好，应该无需赘述（可能转码会避免一些问题，我这里直接放的中文）

3.controller中切换locale

package com.example.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.LocaleResolver;

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

import static org.springframework.web.servlet.i18n.SessionLocaleResolver.LOCALE_SESSION_ATTRIBUTE_NAME;

/**
 * Created by Administrator on 2016/6/11.
 */
@Controller
public class DemoController {
    @Autowired
    LocaleResolver localeResolver;

    @RequestMapping("test")
    public String test(HttpServletRequest request, HttpServletResponse response) {
        HttpSession session=request.getSession();
        localeResolver.setLocale(request,response,Locale.ENGLISH);
        System.out.println(session.getAttribute(LOCALE_SESSION_ATTRIBUTE_NAME));
        return "messages";
    }
}

这里org.springframework.web.servlet.i18n.SessionLocaleResolver.LOCALE_SESSION_ATTRIBUTE_NAME这个字符串常量则是session中默认属性名

可以看一下SessionLocaleResolver的部分源码

public class SessionLocaleResolver extends AbstractLocaleContextResolver {
    public static final String LOCALE_SESSION_ATTRIBUTE_NAME = SessionLocaleResolver.class.getName() + ".LOCALE";
    public static final String TIME_ZONE_SESSION_ATTRIBUTE_NAME = SessionLocaleResolver.class.getName() + ".TIME_ZONE";

locale默认属性名为

org.springframework.web.servlet.i18n.SessionLocaleResolver.LOCALE

setLocale是抽象类AbstractLocaleContextResolver中方法

    public void setLocale(HttpServletRequest request, HttpServletResponse response, Locale locale) {
        this.setLocaleContext(request, response, locale != null?new SimpleLocaleContext(locale):null);
    }

然后看SessionLocaleResolver中setLocaleContext

    public void setLocaleContext(HttpServletRequest request, HttpServletResponse response, LocaleContext localeContext) {
        Locale locale = null;
        TimeZone timeZone = null;
        if(localeContext != null) {
            locale = localeContext.getLocale();
            if(localeContext instanceof TimeZoneAwareLocaleContext) {
                timeZone = ((TimeZoneAwareLocaleContext)localeContext).getTimeZone();
            }
        }

        WebUtils.setSessionAttribute(request, LOCALE_SESSION_ATTRIBUTE_NAME, locale);
        WebUtils.setSessionAttribute(request, TIME_ZONE_SESSION_ATTRIBUTE_NAME, timeZone);
    }

本质上就是一些非空判断取默认，最终给session中的对应属性赋值

4.thymeleaf页面中调用

<!DOCTYPE html>
<html lang="zh_CN"
      xmlns:th="http://www.thymeleaf.org">
<head>
    <title>msg</title>
</head>
<body>
<h1 th:text="${#locale}"></h1>
<h1 th:text="#{sys.test}"></h1>
</body>
</html>

则显示en hello

为了以防万一我还是在上文标红了= =#

end of story