Spring Framework

org.springframework.context.support
Class ReloadableResourceBundleMessageSource

java.lang.Object
  extended by org.springframework.context.support.MessageSourceSupport
      extended by org.springframework.context.support.AbstractMessageSource
          extended by org.springframework.context.support.ReloadableResourceBundleMessageSource
All Implemented Interfaces:
Aware, HierarchicalMessageSource, MessageSource, ResourceLoaderAware

public class ReloadableResourceBundleMessageSource
extends AbstractMessageSource
implements ResourceLoaderAware

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!

Author:
Juergen Hoeller
See Also:
setCacheSeconds(int), setBasenames(java.lang.String...), setDefaultEncoding(java.lang.String), setFileEncodings(java.util.Properties), setPropertiesPersister(org.springframework.util.PropertiesPersister), setResourceLoader(org.springframework.core.io.ResourceLoader), DefaultPropertiesPersister, DefaultResourceLoader, ResourceBundleMessageSource, ResourceBundle

Nested Class Summary
protected  class ReloadableResourceBundleMessageSource.PropertiesHolder
          PropertiesHolder for caching.
 
Field Summary
 
Fields inherited from class org.springframework.context.support.MessageSourceSupport
logger
 
Constructor Summary
ReloadableResourceBundleMessageSource()
           
 
Method Summary
protected  java.util.List<java.lang.String> calculateAllFilenames(java.lang.String basename, java.util.Locale locale)
          Calculate all filenames for the given bundle basename and Locale.
protected  java.util.List<java.lang.String> calculateFilenamesForLocale(java.lang.String basename, java.util.Locale locale)
          Calculate the filenames for the given bundle basename and Locale, appending language code, country code, and variant code.
 void clearCache()
          Clear the resource bundle cache.
 void clearCacheIncludingAncestors()
          Clear the resource bundle caches of this MessageSource and all its ancestors.
protected  ReloadableResourceBundleMessageSource.PropertiesHolder getMergedProperties(java.util.Locale locale)
          Get a PropertiesHolder that contains the actually visible properties for a Locale, after merging all specified resource bundles.
protected  ReloadableResourceBundleMessageSource.PropertiesHolder getProperties(java.lang.String filename)
          Get a PropertiesHolder for the given filename, either from the cache or freshly loaded.
protected  java.util.Properties loadProperties(Resource resource, java.lang.String filename)
          Load the properties from the given resource.
protected  ReloadableResourceBundleMessageSource.PropertiesHolder refreshProperties(java.lang.String filename, ReloadableResourceBundleMessageSource.PropertiesHolder propHolder)
          Refresh the PropertiesHolder for the given bundle filename.
protected  java.text.MessageFormat resolveCode(java.lang.String code, java.util.Locale locale)
          Resolves the given message code as key in the retrieved bundle files, using a cached MessageFormat instance per message code.
protected  java.lang.String resolveCodeWithoutArguments(java.lang.String code, java.util.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).
 void setBasename(java.lang.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(java.lang.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(java.lang.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(java.util.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.
 java.lang.String toString()
           
 
Methods inherited from class org.springframework.context.support.AbstractMessageSource
getDefaultMessage, getMessage, getMessage, getMessage, getMessageFromParent, getMessageInternal, getParentMessageSource, isUseCodeAsDefaultMessage, resolveArguments, setParentMessageSource, setUseCodeAsDefaultMessage
 
Methods inherited from class org.springframework.context.support.MessageSourceSupport
createMessageFormat, formatMessage, isAlwaysUseMessageFormat, renderDefaultMessage, setAlwaysUseMessageFormat
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

ReloadableResourceBundleMessageSource

public ReloadableResourceBundleMessageSource()
Method Detail

setBasename

public void setBasename(java.lang.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:
setBasenames(java.lang.String...), ResourceEditor, ResourceBundle

setBasenames

public void setBasenames(java.lang.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:
setBasename(java.lang.String), ResourceBundle

setDefaultEncoding

public void setDefaultEncoding(java.lang.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:
setFileEncodings(java.util.Properties), PropertiesPersister.load(java.util.Properties, java.io.InputStream)

setFileEncodings

public void setFileEncodings(java.util.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:
setBasenames(java.lang.String...), PropertiesPersister.load(java.util.Properties, java.io.InputStream)

setFallbackToSystemLocale

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.


setCacheSeconds

public void setCacheSeconds(int cacheSeconds)
Set the number of seconds to cache loaded properties files.


setPropertiesPersister

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

The default is a DefaultPropertiesPersister.

See Also:
DefaultPropertiesPersister

setResourceLoader

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.

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

resolveCodeWithoutArguments

protected java.lang.String resolveCodeWithoutArguments(java.lang.String code,
                                                       java.util.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:
AbstractMessageSource.resolveCode(java.lang.String, java.util.Locale), MessageFormat

resolveCode

protected java.text.MessageFormat resolveCode(java.lang.String code,
                                              java.util.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:
AbstractMessageSource.resolveCodeWithoutArguments(String, java.util.Locale)

getMergedProperties

protected ReloadableResourceBundleMessageSource.PropertiesHolder getMergedProperties(java.util.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 java.util.List<java.lang.String> calculateAllFilenames(java.lang.String basename,
                                                                 java.util.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:
setFallbackToSystemLocale(boolean), calculateFilenamesForLocale(java.lang.String, java.util.Locale)

calculateFilenamesForLocale

protected java.util.List<java.lang.String> calculateFilenamesForLocale(java.lang.String basename,
                                                                       java.util.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 Locale.toString().

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

getProperties

protected ReloadableResourceBundleMessageSource.PropertiesHolder getProperties(java.lang.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(java.lang.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

loadProperties

protected java.util.Properties loadProperties(Resource resource,
                                              java.lang.String filename)
                                       throws java.io.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:
java.io.IOException - if properties loading failed

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:
clearCache()

toString

public java.lang.String toString()
Overrides:
toString in class java.lang.Object

Spring Framework