Package org.springframework.context.support

Class ReloadableResourceBundleMessageSource

java.lang.Object
org.springframework.context.support.MessageSourceSupport
org.springframework.context.support.AbstractMessageSource
org.springframework.context.support.AbstractResourceBasedMessageSource
org.springframework.context.support.ReloadableResourceBundleMessageSource
All Implemented Interfaces:
Aware, HierarchicalMessageSource, MessageSource, ResourceLoaderAware
public class ReloadableResourceBundleMessageSource extends AbstractResourceBasedMessageSource implements ResourceLoaderAware
Spring-specific MessageSource implementation that accesses resource bundles using specified basenames, participating in the Spring ApplicationContext's resource loading.

In contrast to the JDK-based ResourceBundleMessageSource, this class uses Properties instances as its custom data structure for messages, loading them via a PropertiesPersister strategy from Spring Resource handles. This strategy is not only capable of reloading files based on timestamp changes, but also of loading properties files with a specific character encoding. It will detect XML property files as well.

Note that the basenames set as "basenames" property are treated in a slightly different fashion than the "basenames" property of ResourceBundleMessageSource. It follows the basic ResourceBundle rule of not specifying file extension or language codes, but can refer to any Spring resource location (instead of being restricted to classpath resources). With a "classpath:" prefix, resources can still be loaded from the classpath, but "cacheSeconds" values other than "-1" (caching forever) might not work reliably in this case.

For a typical web application, message files could be placed in WEB-INF: e.g. a "WEB-INF/messages" basename would find a "WEB-INF/messages.properties", "WEB-INF/messages_en.properties" etc arrangement as well as "WEB-INF/messages.xml", "WEB-INF/messages_en.xml" etc. Note that message definitions in a previous resource bundle will override ones in a later bundle, due to sequential lookup.

This MessageSource can easily be used outside an ApplicationContext: it will use a DefaultResourceLoader as default, simply getting overridden with the ApplicationContext's resource loader if running in a context. It does not have any other specific dependencies.

Thanks to Thomas Achleitner for providing the initial implementation of this message source!

Author:
Juergen Hoeller
See Also:

  • Constructor Details

    • ReloadableResourceBundleMessageSource

      public ReloadableResourceBundleMessageSource()

  • Method Details

    • setFileEncodings

      public void setFileEncodings(Properties fileEncodings)
      Set per-file charsets to use for parsing properties files.

      Only applies to classic properties files, not to XML files.

      Parameters:
      fileEncodings - a Properties with filenames as keys and charset names as values. Filenames have to match the basename syntax, with optional locale-specific components: e.g. "WEB-INF/messages" or "WEB-INF/messages_en".
      See Also:

    • setConcurrentRefresh

      public void setConcurrentRefresh(boolean concurrentRefresh)
      Specify whether to allow for concurrent refresh behavior, i.e. one thread locked in a refresh attempt for a specific cached properties file whereas other threads keep returning the old properties for the time being, until the refresh attempt has completed.

      Default is "true": this behavior is new as of Spring Framework 4.1, minimizing contention between threads. If you prefer the old behavior, i.e. to fully block on refresh, switch this flag to "false".

      Since:
      4.1
      See Also:

    • setPropertiesPersister

      public void setPropertiesPersister(@Nullable PropertiesPersister propertiesPersister)
      Set the PropertiesPersister to use for parsing properties files.

      The default is DefaultPropertiesPersister.

      See Also:

    • setResourceLoader

      public void setResourceLoader(@Nullable ResourceLoader resourceLoader)
      Set the ResourceLoader to use for loading bundle properties files.

      The default is a DefaultResourceLoader. Will get overridden by the ApplicationContext if running in a context, as it implements the ResourceLoaderAware interface. Can be manually overridden when running outside an ApplicationContext.

      Specified by:
      setResourceLoader in interface ResourceLoaderAware
      Parameters:
      resourceLoader - the ResourceLoader object to be used by this object
      See Also:

    • resolveCodeWithoutArguments

      protected String resolveCodeWithoutArguments(String code, Locale locale)
      Resolves the given message code as key in the retrieved bundle files, returning the value found in the bundle as-is (without MessageFormat parsing).
      Overrides:
      resolveCodeWithoutArguments in class AbstractMessageSource
      Parameters:
      code - the code of the message to resolve
      locale - the locale to resolve the code for (subclasses are encouraged to support internationalization)
      Returns:
      the message String, or null if not found
      See Also:

    • resolveCode

      @Nullable protected MessageFormat resolveCode(String code, Locale locale)
      Resolves the given message code as key in the retrieved bundle files, using a cached MessageFormat instance per message code.
      Specified by:
      resolveCode in class AbstractMessageSource
      Parameters:
      code - the code of the message to resolve
      locale - the locale to resolve the code for (subclasses are encouraged to support internationalization)
      Returns:
      the MessageFormat for the message, or null if not found
      See Also:

    • getMergedProperties

      protected ReloadableResourceBundleMessageSource.PropertiesHolder getMergedProperties(Locale locale)
      Get a PropertiesHolder that contains the actually visible properties for a Locale, after merging all specified resource bundles. Either fetches the holder from the cache or freshly loads it.

      Only used when caching resource bundle contents forever, i.e. with cacheSeconds < 0. Therefore, merged properties are always cached forever.

    • calculateAllFilenames

      protected List<String> calculateAllFilenames(String basename, Locale locale)
      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.
      Parameters:
      basename - the basename of the bundle
      locale - the locale
      Returns:
      the List of filenames to check
      See Also:

    • calculateFilenamesForLocale

      protected List<String> calculateFilenamesForLocale(String basename, Locale locale)
      Calculate the filenames for the given bundle basename and Locale, appending language code, country code, and variant code.

      For example, basename "messages", Locale "de_AT_oo" → "messages_de_AT_OO", "messages_de_AT", "messages_de".

      Follows the rules defined by Locale.toString().

      Parameters:
      basename - the basename of the bundle
      locale - the locale
      Returns:
      the List of filenames to check

    • getProperties

      protected ReloadableResourceBundleMessageSource.PropertiesHolder getProperties(String filename)
      Get a PropertiesHolder for the given filename, either from the cache or freshly loaded.
      Parameters:
      filename - the bundle filename (basename + Locale)
      Returns:
      the current PropertiesHolder for the bundle

    • refreshProperties

      protected ReloadableResourceBundleMessageSource.PropertiesHolder refreshProperties(String filename, @Nullable ReloadableResourceBundleMessageSource.PropertiesHolder 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).

      Parameters:
      filename - the bundle filename (basename + Locale)
      propHolder - the current PropertiesHolder for the bundle
      See Also:

    • resolveResource

      protected Resource resolveResource(String filename)
      Resolve the specified bundle filename into a concrete Resource, potentially checking multiple sources or file extensions.

      If no suitable concrete Resource can be resolved, this method returns a Resource for which Resource.exists() returns false, which gets subsequently ignored.

      This can be leveraged to check the last modification timestamp or to load properties from alternative sources — for example, from an XML BLOB in a database, or from properties serialized using a custom format such as JSON.

      The default implementation delegates to the configured ResourceLoader to resolve resources, first checking for an existing Resource with a .properties extension, and otherwise returning a Resource with a .xml extension.

      When overriding this method, loadProperties(Resource, String) must be capable of loading properties from any type of Resource returned by this method. As a consequence, implementors are strongly encouraged to also override loadProperties().

      As an alternative to overriding this method, you can configure a PropertiesPersister that is capable of dealing with all resources returned by this method. Please note, however, that the default loadProperties() implementation uses loadFromXml for XML resources and otherwise uses the two load methods for other types of resources.

      Parameters:
      filename - the bundle filename (basename + Locale)
      Returns:
      the Resource to use
      Since:
      6.1

    • loadProperties

      protected Properties loadProperties(Resource resource, String filename) throws IOException
      Load the properties from the given resource.
      Parameters:
      resource - the resource to load from
      filename - the original bundle filename (basename + Locale)
      Returns:
      the populated Properties instance
      Throws:
      IOException - if properties loading failed

    • newProperties

      protected Properties newProperties()
      Template method for creating a plain new Properties instance. The default implementation simply calls Properties().

      Allows for returning a custom Properties extension in subclasses. Overriding methods should just instantiate a custom Properties subclass, with no further initialization or population to be performed at that point.

      Returns:
      a plain Properties instance
      Since:
      4.2

    • clearCache

      public void clearCache()
      Clear the resource bundle cache. Subsequent resolve calls will lead to reloading of the properties files.

    • clearCacheIncludingAncestors

      public void clearCacheIncludingAncestors()
      Clear the resource bundle caches of this MessageSource and all its ancestors.
      See Also:

    • toString

      public String toString()
      Overrides:
      toString in class Object