LocalizedMessages.java

package top.infra.localization;

import org.reflections.Reflections;
import org.springframework.context.i18n.LocaleContextHolder;

import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Set;

import top.infra.core.ErrorMessage;

/**
 * Created by zhuowan on 2018/3/30 18:04.
 * Description:
 */
public class LocalizedMessages {

  private transient static final Map<MessageLocale, Map<String, String>> messageCache;
  private static boolean initialized = false;

  static {
    messageCache = new HashMap<>();
    init();
  }

  /**
   * 1. 第一步加载所有的locales及所有的messages
   * 2. 获取message优先级：
   * priority 1: Forced 强制加载的类型message
   * priority 2: 指定类型的message类型
   * priority 3: 默认的message类型 （目前把US当作默认类型）
   * priority 4: 抛出异常
   */
  public static String getMessageByLocale(final ErrorMessage message, final Locale locale) {
    String resultMsg = getMessageByLocaleAndMessage(message, getLocale(locale));
    if (resultMsg != null) {
      return resultMsg;
    }
    throw new RuntimeException("Invalid common locale message usage");
  }

  /**
   * 初始化所有message信息
   */
  private static void init() {
    if (!initialized) {
      final Reflections reflections = new Reflections();
      final Set<Class<?>> bundles = reflections.getTypesAnnotatedWith(LocalizedMessageBundle.class);
      for (final MessageLocale locale : MessageLocale.values()) { // all locales
        final Map<String, String> enumConstants = new HashMap<>();
        for (final Class bundle : bundles) {
          final LocalizedMessageBundle annotation = (LocalizedMessageBundle) bundle.getAnnotation(LocalizedMessageBundle.class);
          final MessageLocale bundleLocale = annotation.value();
          if (locale == bundleLocale) {
            arrayToMap(enumConstants, bundle.getEnumConstants());
          }
        }
        messageCache.putIfAbsent(locale, enumConstants);
      }
      initialized = true;
    }
  }

  private static void arrayToMap(final Map<String, String> map, final Object[] enums) {
    if (map != null && enums != null) {
      for (final Object enu : enums) {
        final ErrorMessage message = (ErrorMessage) enu;
        map.putIfAbsent(message.getName(), message.getText());
      }
    }
  }

  private static MessageLocale getLocale(final Locale locale) {
    final String country = locale != null ? locale.getCountry() : LocaleContextHolder.getLocale().getCountry();
    return MessageLocale.of(country);
  }

  private static String getMessageByLocaleAndMessage(ErrorMessage message, MessageLocale messageLocale) {
    //priority 1 Forced messageLocale Message
    String finalMessage = messageCache.get(MessageLocale.FORCED).get(message.getName());
    if (finalMessage == null) {
      //priority 2 Specific messageLocale message
      finalMessage = messageCache.get(messageLocale).get(message.getName());
      if (finalMessage == null) {
        //priority 3 Default message
        finalMessage = messageCache.get(MessageLocale.DEFAULT).get(message.getName());
      }
    }
    return finalMessage;
  }
}