文章作者:jqpeng
原文链接: Spring boot国际化
国际化主要是引入了MessageSource，我们简单看下如何使用，以及其原理。
1.1 设置资源文件
在 properties新建i18n目录
新建message文件：
messages.properties
error.title=Your request cannot be processed
messages_zh_CN.properties
error.title=您的请求无法处理
1.2 配置
修改properties文件的目录：在application.yml或者application.properties中配置 spring.message.basename
spring:
application:
name: test-worklog
messages:
basename: i18n/messages
encoding: UTF-8
1.3 使用
引用自动注解的MessageSource,调用messageSource.getMessage即可，注意，需要通过 LocaleContextHolder.getLocale()获取当前的地区。
@Autowired
private MessageSource messageSource;
/**
* 国际化
*
* @param result
* @return
*/
public String getMessage(String result, Object[] params) {
String message = "";
try {
Locale locale = LocaleContextHolder.getLocale();
message = messageSource.getMessage(result, params, locale);
} catch (Exception e) {
LOGGER.error("parse message error! ", e);
}
return message;
}
如何设置个性化的地区呢? forLanguageTag 即可
Locale locale = Locale.forLanguageTag(user.getLangKey());
1.4 原理分析
MessageSourceAutoConfiguration中，实现了autoconfig
@Configuration
@ConditionalOnMissingBean(value = MessageSource.class, search = SearchStrategy.CURRENT)
@AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE)
@Conditional(ResourceBundleCondition.class)
@EnableConfigurationProperties
@ConfigurationProperties(prefix = "spring.messages")
public class MessageSourceAutoConfiguration {
该类一方面读取配置文件，一方面创建了MessageSource的实例:
@Beanpublic MessageSource messageSource() { ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource(); if (StringUtils.hasText(this.basename)) { messageSource.setBasenames(StringUtils.commaDelimitedListToStringArray( StringUtils.trimAllWhitespace(this.basename))); } if (this.encoding != null) { messageSource.setDefaultEncoding(this.encoding.name()); } messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale); messageSource.setCacheSeconds(this.cacheSeconds); messageSource.setAlwaysUseMessageFormat(this.alwaysUseMessageFormat); return messageSource;}
因此，默认是加载的ResourceBundleMessageSource，该类派生与于AbstractResourceBasedMessageSource
@Overridepublic final String getMessage(String code, Object[] args, String defaultMessage, Locale locale) { String msg = getMessageInternal(code, args, locale); if (msg != null) { return msg; } if (defaultMessage == null) { String fallback = getDefaultMessage(code); if (fallback != null) { return fallback; } } return renderDefaultMessage(defaultMessage, args, locale);}
最终是调用resolveCode来获取message，通过ResourceBundle来获取message
@Overrideprotected MessageFormat resolveCode(String code, Locale locale) { // 遍历语言文件路径 Set<String> basenames = getBasenameSet(); for (String basename : basenames) { ResourceBundle bundle = getResourceBundle(basename, locale); if (bundle != null) { MessageFormat messageFormat = getMessageFormat(bundle, code, locale); if (messageFormat != null) { return messageFormat; } } } return null;}
// 获取ResourceBundle
protected ResourceBundle getResourceBundle(String basename, Locale locale) { if (getCacheMillis() >= 0) { // Fresh ResourceBundle.getBundle call in order to let ResourceBundle // do its native caching, at the expense of more extensive lookup steps. return doGetBundle(basename, locale); } else { // Cache forever: prefer locale cache over repeated getBundle calls. synchronized (this.cachedResourceBundles) { Map<Locale, ResourceBundle> localeMap = this.cachedResourceBundles.get(basename); if (localeMap != null) { ResourceBundle bundle = localeMap.get(locale); if (bundle != null) { return bundle; } } try { ResourceBundle bundle = doGetBundle(basename, locale); if (localeMap == null) { localeMap = new HashMap<Locale, ResourceBundle>(); this.cachedResourceBundles.put(basename, localeMap); } localeMap.put(locale, bundle); return bundle; } catch (MissingResourceException ex) { if (logger.isWarnEnabled()) { logger.warn("ResourceBundle [" + basename + "] not found for MessageSource: " + ex.getMessage()); } // Assume bundle not found // -> do NOT throw the exception to allow for checking parent message source. return null; } } }}
// ResourceBundle
protected ResourceBundle doGetBundle(String basename, Locale locale) throws MissingResourceException { return ResourceBundle.getBundle(basename, locale, getBundleClassLoader(), new MessageSourceControl());
}
最后来看getMessageFormat：
/** * Return a MessageFormat for the given bundle and code, * fetching already generated MessageFormats from the cache. * @param bundle the ResourceBundle to work on * @param code the message code to retrieve * @param locale the Locale to use to build the MessageFormat * @return the resulting MessageFormat, or {@code null} if no message * defined for the given code * @throws MissingResourceException if thrown by the ResourceBundle */protected MessageFormat getMessageFormat(ResourceBundle bundle, String code, Locale locale) throws MissingResourceException {
synchronized (this.cachedBundleMessageFormats) { // 从缓存读取 Map<String, Map<Locale, MessageFormat>> codeMap = this.cachedBundleMessageFormats.get(bundle); Map<Locale, MessageFormat> localeMap = null; if (codeMap != null) { localeMap = codeMap.get(code); if (localeMap != null) { MessageFormat result = localeMap.get(locale); if (result != null) { return result; } } } // 缓存miss，从bundle读取 String msg = getStringOrNull(bundle, code); if (msg != null) { if (codeMap == null) { codeMap = new HashMap<String, Map<Locale, MessageFormat>>(); this.cachedBundleMessageFormats.put(bundle, codeMap); } if (localeMap == null) { localeMap = new HashMap<Locale, MessageFormat>(); codeMap.put(code, localeMap); } MessageFormat result = createMessageFormat(msg, locale); localeMap.put(locale, result); return result; }
return null; }}
作者：Jadepeng
出处：jqpeng的技术记事本–http://www.cnblogs.com/xiaoqi
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