应用国际化（2） _JAVA_编程开发_程序员俱乐部

上一篇介绍了应用国际化需要考虑的问题，本篇介绍后端如何实现提示语的国际化。

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先说说系统框架，本项目采用React + Spring + MyBatis + RabbitMQ + Redis等主流框架组合搭建而成，前后端分离。不得不说，在Spring?Framework的加持下，做什么事情都方便的多。

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1、添加LangCookieFilter，拦截参数中带有lang的请求，并将语言标识存入cookie。

class="java" name="code">import java.io.IOException;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.lang3.StringUtils;

public class LangCookieFilter implements Filter {
    // 默认参数名称
    public static final String DEFAULT_PARAM_NAME = "lang";
    
	@Override
	public void init(FilterConfig filterConfig) throws ServletException {}

	@Override
	public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain)
			throws IOException, ServletException {
		
		HttpServletRequest request = (HttpServletRequest)arg0;
		HttpServletResponse response = (HttpServletResponse)arg1;
		
		String lang = request.getParameter(DEFAULT_PARAM_NAME);
		if(StringUtils.isNotEmpty(lang)){
			Cookie[] cookies = request.getCookies();
			boolean flag = false;
			if(cookies != null){
				for (Cookie cookie : cookies) {
					if(cookie.getName().equals(DEFAULT_PARAM_NAME)){
						cookie.setValue(lang);
						flag = true;
					}				
				}				
			}
			if(!flag){
				Cookie cookie = new Cookie(DEFAULT_PARAM_NAME, lang);
				cookie.setHttpOnly(true);
				response.addCookie(cookie);
			}			
		}
		chain.doFilter(arg0, arg1); 
	}

	@Override
	public void destroy() {}

}

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2、配置web.xml? 将LangCookieFilter添加到web.xml中。另外还需配置monospace;">RequestContextListener监听，方便在MessageSourceUtils中使用。

	<!-- langCookieFilter -->
	<filter>
		<filter-name>langCookieFilter</filter-name>
		<filter-class>com.rongdu.framework.core.common.cookie.LangCookieFilter</filter-class>
	</filter>
	<filter-mapping>
		<filter-name>langCookieFilter</filter-name>
		<url-pattern>*.htm</url-pattern>
	</filter-mapping>
	
<listener>
        <listener-class>org.springframework.web.context.request.RequestContextListener</listener-class>  
</listener>

? ?后来看了RequestContextListener代码，感觉LangCookieFilter的做法有些多余，后续再研究。

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3、springmvc配置文件中添加i18n支持

	  
	<bean id="localeResolver" class="org.springframework.web.servlet.i18n.SessionLocaleResolver">
		<property name="defaultLocale" value="zh_CN"/>
	</bean>  
	
	<!-- 国际化的消息资源文件（本系统中主要用于显示/错误消息定制） -->  
	<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">  
	    <property name="basenames">  
	        <list>  
	            <!-- 在web环境中一定要定位到classpath 否则默认到当前web应用下找  -->  
	            <value>classpath:i18n/message</value>  
	            <value>classpath:org/hibernate/validator/ValidationMessages</value>  
	        </list>  
	    </property>  
	    <property name="useCodeAsDefaultMessage" value="false"/>  
	    <property name="defaultEncoding" value="UTF-8"/>  
	    <property name="cacheSeconds" value="60"/>  
	</bean>

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4、添加MessageSourceUtils工具类，获取国际化文件中国际化字段信息

import java.util.Locale;

import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServletRequest;

import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import com.rongdu.framework.core.common.context.Constant;
import com.rongdu.framework.core.common.cookie.LangCookieFilter;
/**
 * 国际化语言工具类
 * @author lh@erongdu.com
 * @version 2.0
 * @since 2018-12-26
 *
 */
public class LangUtil {
	
	public static String get(){
		HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getRequest();
    	Cookie[] cookies = request.getCookies();
    	if(cookies != null){    		
	    	for (Cookie cookie : cookies) {
				if(cookie.getName().equals(LangCookieFilter.DEFAULT_PARAM_NAME)){
					return cookie.getValue();
				}
	    	}
		}
    	return Constant.DEFAULT_LANG;		
	}

	public static Locale getLocale(){
    	return new Locale(get());
    }
}

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import java.util.Locale;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.MessageSource;
import org.springframework.stereotype.Component;

/**
 * 资源国际化工具类
 * @author lh@erongdu.com
 * @version 2.0
 * @since 2018-12-24
 */
@Component
public class MessageSourceUtils {

    // 日志
    private static final Logger LOGGER = LoggerFactory.getLogger(MessageSourceUtils.class);
    
    private static MessageSource messageSource;
    
    @Autowired
    public void setMessageSource(MessageSource messageSource) {
		MessageSourceUtils.messageSource = messageSource;
	}


    /**
     * 获取国际化文件中国际化字段信息
     * @param key	国际化参数
     * @param args	动态参数
     * @return
     */
    public static String getMessage(String key, Object[] args) {
    	try {
    		return messageSource.getMessage(key, args, key, LangUtil.getLocale());
    	} catch (Exception e) {
    		LOGGER.error(e.getMessage());
    	}
    	return key;
    }
    
    /**
     * 可供后台使用
     * 获取国际化文件中中文字段信息
     * @param key	国际化参数
     * @param args	动态参数
     * @return
     */
    public static String getChineseMessage(String key, Object[] args) {
    	try {
    		return messageSource.getMessage(key, args, key, Locale.CHINESE);
    	} catch (Exception e) {
    		LOGGER.error(e.getMessage());
    	}
    	return key;
    }
    
//	/**
//     * 获取国际化文件中国际化字段信息
//     * @param key	国际化key
//     * @param args	动态参数
//     * @return
//     */
//    public static String getMessage(String key, Object[] args) {
//        try {
//            Locale locale = LocaleContextHolder.getLocale();
//            return messageSource.getMessage(key, args, key, locale);
//        } catch (Exception e) {
//        	LOGGER.error(e.getMessage());
//        }
//        return key;
//    }

}

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5、在Controller、Service等层使用MessageSourceUtils工具类

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;

import com.rongdu.framework.core.common.util.MessageSourceUtils;

@Controller
public class IndexController{

	/**
	 * 首页
	 * @return
	 * @throws Exception
	 */
	@RequestMapping(value = "/home.htm")
	public String home(Model model){
		model.addAttribute("title", MessageSourceUtils.getMessage("title", null));
		return "home";
	}
	
}

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