reloadableresourcebundlemessagesource.java

一个关于Spring框架的示例应用程序,简单使用,可以参考.

			mergedHolder = new PropertiesHolder(mergedProps, -1);
			for (int i = this.basenames.length - 1; i >= 0; i--) {
				List filenames = calculateAllFilenames(this.basenames[i], locale);
				for (int j = filenames.size() - 1; j >= 0; j--) {
					String filename = (String) filenames.get(j);
					PropertiesHolder propHolder = getProperties(filename);
					if (propHolder.getProperties() != null) {
						mergedProps.putAll(propHolder.getProperties());
					}
				}
			}
			this.cachedMergedProperties.put(locale, mergedHolder);
			return mergedHolder;
		}
	}

	/**
	 * Calculate all filenames for the given bundle basename and Locale.
	 * Will calculate filenames for the given Locale, the system Locale
	 * (if applicable), and the default file.
	 * @param basename the basename of the bundle
	 * @param locale the locale
	 * @return the List of filenames to check
	 * @see #setFallbackToSystemLocale
	 * @see #calculateFilenamesForLocale
	 */
	protected List calculateAllFilenames(String basename, Locale locale) {
		synchronized (this.cachedFilenames) {
			Map localeMap = (Map) this.cachedFilenames.get(basename);
			if (localeMap != null) {
				List filenames = (List) localeMap.get(locale);
				if (filenames != null) {
					return filenames;
				}
			}
			List filenames = new ArrayList(7);
			filenames.addAll(calculateFilenamesForLocale(basename, locale));
			if (this.fallbackToSystemLocale && !locale.equals(Locale.getDefault())) {
				List fallbackFilenames = calculateFilenamesForLocale(basename, Locale.getDefault());
				for (Iterator it = fallbackFilenames.iterator(); it.hasNext();) {
					String fallbackFilename = (String) it.next();
					if (!filenames.contains(fallbackFilename)) {
						// entry for fallback locale that isn't alread in filenames list
						filenames.add(fallbackFilename);
					}
				}
			}
			filenames.add(basename);
			if (localeMap != null) {
				localeMap.put(locale, filenames);
			}
			else {
				localeMap = new HashMap();
				localeMap.put(locale, filenames);
				this.cachedFilenames.put(basename, localeMap);
			}
			return filenames;
		}
	}

	/**
	 * Calculate the filenames for the given bundle basename and Locale,
	 * appending language code, country code, and variant code.
	 * E.g.: basename "messages", Locale "de_AT_oo" -> "messages_de_AT_OO",
	 * "messages_de_AT", "messages_de".
	 * @param basename the basename of the bundle
	 * @param locale the locale
	 * @return the List of filenames to check
	 */
	protected List calculateFilenamesForLocale(String basename, Locale locale) {
		List result = new ArrayList(3);
		String language = locale.getLanguage();
		String country = locale.getCountry();
		String variant = locale.getVariant();
		StringBuffer temp = new StringBuffer(basename);

		if (language.length() > 0) {
			temp.append('_').append(language);
			result.add(0, temp.toString());
		}

		if (country.length() > 0) {
			temp.append('_').append(country);
			result.add(0, temp.toString());
		}

		if (variant.length() > 0) {
			temp.append('_').append(variant);
			result.add(0, temp.toString());
		}

		return result;
	}

	/**
	 * Get a PropertiesHolder for the given filename, either from the
	 * cache or freshly loaded.
	 */
	protected PropertiesHolder getProperties(String filename) {
		synchronized (this.cachedProperties) {
			PropertiesHolder propHolder = (PropertiesHolder) this.cachedProperties.get(filename);
			if (propHolder != null &&
					(propHolder.getRefreshTimestamp() < 0 ||
					 propHolder.getRefreshTimestamp() > System.currentTimeMillis() - this.cacheMillis)) {
				// up to date
				return propHolder;
			}
			return refreshProperties(filename, propHolder);
		}
	}

	/**
	 * Refresh the PropertiesHolder for the given bundle filename.
	 * The holder can be null if not cached before, or a timed-out cache entry
	 * (potentially getting re-validated against the current last-modified timestamp).
	 */
	protected PropertiesHolder refreshProperties(String filename, PropertiesHolder propHolder) {
		long refreshTimestamp = (this.cacheMillis < 0) ? -1 : System.currentTimeMillis();

		Resource resource = this.resourceLoader.getResource(filename + PROPERTIES_SUFFIX);
		try {
			long fileTimestamp = -1;
			if (this.cacheMillis >= 0) {
				// last-modified timestamp of file will just be read if caching with timeout
				// (allowing to use classpath resources if caching forever)
				fileTimestamp = resource.getFile().lastModified();
				if (fileTimestamp == 0) {
					throw new IOException("File [" + resource.getFile().getAbsolutePath() + "] does not exist");
				}
				if (propHolder != null && propHolder.getFileTimestamp() == fileTimestamp) {
					if (logger.isDebugEnabled()) {
						logger.debug("Re-caching properties for filename [" + filename + "] - file hasn't been modified");
					}
					propHolder.setRefreshTimestamp(refreshTimestamp);
					return propHolder;
				}
			}

			InputStream is = resource.getInputStream();
			Properties props = new Properties();
			try {
				String encoding = null;
				if (this.fileEncodings != null) {
					encoding = this.fileEncodings.getProperty(filename);
				}
				if (encoding == null) {
					encoding = this.defaultEncoding;
				}
				if (encoding != null) {
					if (logger.isDebugEnabled()) {
						logger.debug("Loading properties for filename [" + filename + "] with encoding '" + encoding + "'");
					}
					this.propertiesPersister.load(props, new InputStreamReader(is, encoding));
				}
				else {
					if (logger.isDebugEnabled()) {
						logger.debug("Loading properties for filename [" + filename + "]");
					}
					this.propertiesPersister.load(props, is);
				}
				propHolder = new PropertiesHolder(props, fileTimestamp);
			}
			finally {
				is.close();
			}
		}
		catch (IOException ex) {
			if (logger.isDebugEnabled()) {
				logger.debug("Properties file [" + filename + "] not found for MessageSource: " + ex.getMessage());
			}
			// empty holder representing "not found"
			propHolder = new PropertiesHolder();
		}

		propHolder.setRefreshTimestamp(refreshTimestamp);
		this.cachedProperties.put(filename, propHolder);
		return propHolder;
	}

	/**
	 * Clear the resource bundle cache.
	 * Following resolve calls will lead to reloading of the properties files.
	 */
	public void clearCache() {
		logger.info("Clearing resource bundle cache");
		synchronized (this.cachedProperties) {
			this.cachedProperties.clear();
		}
	}

	/**
	 * Clear the resource bundle caches of this MessageSource and all its ancestors.
	 * @see #clearCache
	 */
	public void clearCacheIncludingAncestors() {
		clearCache();
		if (getParentMessageSource() instanceof ReloadableResourceBundleMessageSource) {
			((ReloadableResourceBundleMessageSource) getParentMessageSource()).clearCacheIncludingAncestors();
		}
	}

	public String toString() {
		return getClass().getName() + ": basenames=[" + StringUtils.arrayToCommaDelimitedString(this.basenames) + "]";
	}


	/**
	 * PropertiesHolder for caching.
	 * Stores the last-modified timestamp of the source file for efficient
	 * change detection, and the timestamp of the last refresh attempt
	 * (updated every time the cache entry gets re-validated).
	 */
	protected class PropertiesHolder {

		private Properties properties;

		private long fileTimestamp = -1;

		private long refreshTimestamp = -1;

		/** Cache to hold already generated MessageFormats per message code */
		private final Map cachedMessageFormats = new HashMap();

		public PropertiesHolder(Properties properties, long fileTimestamp) {
			this.properties = properties;
			this.fileTimestamp = fileTimestamp;
		}

		public PropertiesHolder() {
		}

		public Properties getProperties() {
			return properties;
		}

		public long getFileTimestamp() {
			return fileTimestamp;
		}

		public void setRefreshTimestamp(long refreshTimestamp) {
			this.refreshTimestamp = refreshTimestamp;
		}

		public long getRefreshTimestamp() {
			return refreshTimestamp;
		}

		public String getProperty(String code) {
			if (this.properties == null) {
				return null;
			}
			return this.properties.getProperty(code);
		}

		public MessageFormat getMessageFormat(String code, Locale locale) {
			if (this.properties == null) {
				return null;
			}
			synchronized (this.cachedMessageFormats) {
				Map localeMap = (Map) this.cachedMessageFormats.get(code);
				if (localeMap != null) {
					MessageFormat result = (MessageFormat) localeMap.get(locale);
					if (result != null) {
						return result;
					}
				}
				String msg = this.properties.getProperty(code);
				if (msg != null) {
					if (localeMap == null) {
						localeMap = new HashMap();
						this.cachedMessageFormats.put(code, localeMap);
					}
					MessageFormat result = createMessageFormat(msg, locale);
					localeMap.put(locale, result);
					return result;
				}
				return null;
			}
		}
	}

}