public class

ReloadableResourceBundleMessageSource

extends AbstractMessageSource
implements ResourceLoaderAware
java.lang.Object
   ↳ org.springframework.context.support.MessageSourceSupport
     ↳ org.springframework.context.support.AbstractMessageSource
       ↳ org.springframework.context.support.ReloadableResourceBundleMessageSource

Class Overview

MessageSource implementation that accesses resource bundles using specified basenames. This class uses Properties instances as its custom data structure for messages, loading them via a PropertiesPersister strategy: The default strategy is capable of loading properties files with a specific character encoding, if desired.

In contrast to ResourceBundleMessageSource, this class supports reloading of properties files through the "cacheSeconds" setting, and also through programmatically clearing the properties cache. Since application servers typically cache all files loaded from the classpath, it is necessary to store resources somewhere else (for example, in the "WEB-INF" directory of a web app). Otherwise changes of files in the classpath will not be reflected in the application.

Note that the base names 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) will not work in this case.

This MessageSource implementation is usually slightly faster than ResourceBundleMessageSource, which builds on ResourceBundle - in the default mode, i.e. when caching forever. With "cacheSeconds" set to 1, message lookup takes about twice as long - with the benefit that changes in individual properties files are detected with a maximum delay of 1 second. Higher "cacheSeconds" values usually do not make a significant difference.

This MessageSource can easily be used outside of 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!

See Also

Summary

Nested Classes
class ReloadableResourceBundleMessageSource.PropertiesHolder PropertiesHolder for caching. 
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Inherited Fields
From class org.springframework.context.support.MessageSourceSupport
Public Constructors
ReloadableResourceBundleMessageSource()
Public Methods
void clearCache()
Clear the resource bundle cache.
void clearCacheIncludingAncestors()
Clear the resource bundle caches of this MessageSource and all its ancestors.
void setBasename(String basename)
Set a single basename, following the basic ResourceBundle convention of not specifying file extension or language codes, but in contrast to ResourceBundleMessageSource referring to a Spring resource location: e.g.
void setBasenames(String[] basenames)
Set an array of basenames, each following the basic ResourceBundle convention of not specifying file extension or language codes, but in contrast to ResourceBundleMessageSource referring to a Spring resource location: e.g.
void setCacheSeconds(int cacheSeconds)
Set the number of seconds to cache loaded properties files.
void setDefaultEncoding(String defaultEncoding)
Set the default charset to use for parsing properties files.
void setFallbackToSystemLocale(boolean fallbackToSystemLocale)
Set whether to fall back to the system Locale if no files for a specific Locale have been found.
void setFileEncodings(Properties fileEncodings)
Set per-file charsets to use for parsing properties files.
void setPropertiesPersister(PropertiesPersister propertiesPersister)
Set the PropertiesPersister to use for parsing properties files.
void setResourceLoader(ResourceLoader resourceLoader)
Set the ResourceLoader to use for loading bundle properties files.
String toString()
Protected Methods
List<String> calculateAllFilenames(String basename, Locale locale)
Calculate all filenames for the given bundle basename and Locale.
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.
ReloadableResourceBundleMessageSource.PropertiesHolder getMergedProperties(Locale locale)
Get a PropertiesHolder that contains the actually visible properties for a Locale, after merging all specified resource bundles.
ReloadableResourceBundleMessageSource.PropertiesHolder getProperties(String filename)
Get a PropertiesHolder for the given filename, either from the cache or freshly loaded.
Properties loadProperties(Resource resource, String filename)
Load the properties from the given resource.
ReloadableResourceBundleMessageSource.PropertiesHolder refreshProperties(String filename, ReloadableResourceBundleMessageSource.PropertiesHolder propHolder)
Refresh the PropertiesHolder for the given bundle filename.
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.
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).
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Inherited Methods
From class org.springframework.context.support.AbstractMessageSource
From class org.springframework.context.support.MessageSourceSupport
From class java.lang.Object
From interface org.springframework.context.HierarchicalMessageSource
From interface org.springframework.context.MessageSource
From interface org.springframework.context.ResourceLoaderAware

Public Constructors

public ReloadableResourceBundleMessageSource ()

Public Methods

public void clearCache ()

Clear the resource bundle cache. Subsequent resolve calls will lead to reloading of the properties files.

public void clearCacheIncludingAncestors ()

Clear the resource bundle caches of this MessageSource and all its ancestors.

See Also

public void setBasename (String basename)

Set a single basename, following the basic ResourceBundle convention of not specifying file extension or language codes, but in contrast to ResourceBundleMessageSource referring to a Spring resource location: e.g. "WEB-INF/messages" for "WEB-INF/messages.properties", "WEB-INF/messages_en.properties", etc.

XML properties files are also supported: .g. "WEB-INF/messages" will find and load "WEB-INF/messages.xml", "WEB-INF/messages_en.xml", etc as well.

Parameters
basename the single basename
See Also

public void setBasenames (String[] basenames)

Set an array of basenames, each following the basic ResourceBundle convention of not specifying file extension or language codes, but in contrast to ResourceBundleMessageSource referring to a Spring resource location: e.g. "WEB-INF/messages" for "WEB-INF/messages.properties", "WEB-INF/messages_en.properties", etc.

XML properties files are also supported: .g. "WEB-INF/messages" will find and load "WEB-INF/messages.xml", "WEB-INF/messages_en.xml", etc as well.

The associated resource bundles will be checked sequentially when resolving a message code. Note that message definitions in a previous resource bundle will override ones in a later bundle, due to the sequential lookup.

Parameters
basenames an array of basenames
See Also

public void setCacheSeconds (int cacheSeconds)

Set the number of seconds to cache loaded properties files.

  • Default is "-1", indicating to cache forever (just like java.util.ResourceBundle).
  • A positive number will cache loaded properties files for the given number of seconds. This is essentially the interval between refresh checks. Note that a refresh attempt will first check the last-modified timestamp of the file before actually reloading it; so if files don't change, this interval can be set rather low, as refresh attempts will not actually reload.
  • A value of "0" will check the last-modified timestamp of the file on every message access. Do not use this in a production environment!

public void setDefaultEncoding (String defaultEncoding)

Set the default charset to use for parsing properties files. Used if no file-specific charset is specified for a file.

Default is none, using the java.util.Properties default encoding.

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

Parameters
defaultEncoding the default charset
See Also

public void setFallbackToSystemLocale (boolean fallbackToSystemLocale)

Set whether to fall back to the system Locale if no files for a specific Locale have been found. Default is "true"; if this is turned off, the only fallback will be the default file (e.g. "messages.properties" for basename "messages").

Falling back to the system Locale is the default behavior of java.util.ResourceBundle. However, this is often not desirable in an application server environment, where the system Locale is not relevant to the application at all: Set this flag to "false" in such a scenario.

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

public void setPropertiesPersister (PropertiesPersister propertiesPersister)

Set the PropertiesPersister to use for parsing properties files.

The default is a DefaultPropertiesPersister.

See Also

public void setResourceLoader (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 of an ApplicationContext.

Parameters
resourceLoader ResourceLoader object to be used by this object
See Also

public String toString ()

Protected Methods

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

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. E.g.: basename "messages", Locale "de_AT_oo" -> "messages_de_AT_OO", "messages_de_AT", "messages_de".

Follows the rules defined by toString().

Parameters
basename the basename of the bundle
locale the locale
Returns
  • the List of filenames to check

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.

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

protected Properties loadProperties (Resource resource, String filename)

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

protected ReloadableResourceBundleMessageSource.PropertiesHolder refreshProperties (String filename, 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

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.

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

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).

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