org.springframework.context.support
Class AbstractMessageSource

java.lang.Object
  org.springframework.context.support.AbstractMessageSource

All Implemented Interfaces:

HierarchicalMessageSource, MessageSource

Direct Known Subclasses:

ReloadableResourceBundleMessageSource, ResourceBundleMessageSource, StaticMessageSource

public abstract class AbstractMessageSource
extends Object
implements HierarchicalMessageSource

Abstract implementation of HierarchicalMessageSource interface, making it easy to implement a custom MessageSource. Subclasses must implement the abstract resolveCode method.

Supports not only MessageSourceResolvables as primary messages but also resolution of message arguments that are in turn MessageSourceResolvables themselves.

This class does not implement caching, thus subclasses can dynamically change messages over time. Subclasses are encouraged to cache their messages in a modification-aware fashion.

Author:

Rod Johnson, Juergen Hoeller

See Also:

resolveCode(java.lang.String, java.util.Locale)

Field Summary

protected Log

logger

Constructor Summary

AbstractMessageSource()

Method Summary

protected MessageFormat	createMessageFormat(String msg, Locale locale) Create a MessageFormat for the given message and Locale.
String	getMessage(MessageSourceResolvable resolvable, Locale locale) Try to resolve the message using all the attributes contained within the MessageSourceResolvable argument that was passed in.
String	getMessage(String code, Object[] args, Locale locale) Try to resolve the message.
String	getMessage(String code, Object[] args, String defaultMessage, Locale locale) Try to resolve the message.
protected String	getMessageInternal(String code, Object[] args, Locale locale) Resolve the given code and arguments as message in the given Locale, returning null if not found.
MessageSource	getParentMessageSource() Return the parent of this MessageSource, or null if none.
protected Object[]	resolveArguments(Object[] args, Locale locale) Search through the given array of objects, find any MessageSourceResolvable objects and resolve them.
protected abstract MessageFormat	resolveCode(String code, Locale locale) Subclasses must implement this method to resolve a message.
protected String	resolveCodeWithoutArguments(String code, Locale locale) Subclasses can override this method to resolve a message without arguments in an optimized fashion, i.e. to resolve a message without involving a MessageFormat.
void	setParentMessageSource(MessageSource parent) Set the parent that will be used to try to resolve messages that this object can't resolve.
void	setUseCodeAsDefaultMessage(boolean useCodeAsDefaultMessage) Set whether to use the message code as default message instead of throwing a NoSuchMessageException.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected final Log logger

Constructor Detail

AbstractMessageSource

public AbstractMessageSource()

Method Detail

setParentMessageSource

public void setParentMessageSource(MessageSource parent)

Description copied from interface: HierarchicalMessageSource

Set the parent that will be used to try to resolve messages that this object can't resolve.

Specified by:

setParentMessageSource in interface HierarchicalMessageSource

Parameters:

parent - parent MessageSource that will be used to resolve messages that this object can't resolve. May be null, in which case no further resolution is possible.

getParentMessageSource

public MessageSource getParentMessageSource()

Description copied from interface: HierarchicalMessageSource

Return the parent of this MessageSource, or null if none.

Specified by:

getParentMessageSource in interface HierarchicalMessageSource

setUseCodeAsDefaultMessage

public void setUseCodeAsDefaultMessage(boolean useCodeAsDefaultMessage)

Set whether to use the message code as default message instead of throwing a NoSuchMessageException. Useful for development and debugging. Default is false.

Note: In case of a MessageSourceResolvable with multiple codes (like a FieldError) and a MessageSource that has a parent MessageSource, do not activate "useCodeAsDefaultMessage" in the parent: Else, you'll get the first code returned as message by the parent, without attempts to check further codes.

To be able to work with "useCodeAsDefaultMessage" turned on in the parent, AbstractMessageSource and AbstractApplicationContext contain special checks to delegate to the internal getMessageInternal method if available. In general, it is recommended to just use "useCodeAsDefaultMessage" during development and not rely on it in production in the first place, though.

See Also:

getMessage(String, Object[], Locale), getMessageInternal(java.lang.String, java.lang.Object[], java.util.Locale), FieldError

getMessage

public final String getMessage(String code,
                               Object[] args,
                               String defaultMessage,
                               Locale locale)

Description copied from interface: MessageSource

Try to resolve the message. Return default message if no message was found.

Specified by:

getMessage in interface MessageSource

Parameters:

code - the code to lookup up, such as 'calculator.noRateSet'. Users of this class are encouraged to base message names on the relevant fully qualified class name, thus avoiding conflict and ensuring maximum clarity.

args - array of arguments that will be filled in for params within the message (params look like "{0}", "{1,date}", "{2,time}" within a message), or null if none.

defaultMessage - String to return if the lookup fails

locale - the Locale in which to do the lookup

Returns:

the resolved message if the lookup was successful; otherwise the default message passed as a parameter

See Also:

java.text.MessageFormat

getMessage

public final String getMessage(String code,
                               Object[] args,
                               Locale locale)
                        throws NoSuchMessageException

Description copied from interface: MessageSource

Try to resolve the message. Treat as an error if the message can't be found.

Specified by:

getMessage in interface MessageSource

Parameters:

code - the code to lookup up, such as 'calculator.noRateSet'

args - Array of arguments that will be filled in for params within the message (params look like "{0}", "{1,date}", "{2,time}" within a message), or null if none.

locale - the Locale in which to do the lookup

Returns:

the resolved message

Throws:

NoSuchMessageException - if the message wasn't found

See Also:

java.text.MessageFormat

getMessage

public final String getMessage(MessageSourceResolvable resolvable,
                               Locale locale)
                        throws NoSuchMessageException

Description copied from interface: MessageSource

Try to resolve the message using all the attributes contained within the MessageSourceResolvable argument that was passed in.

NOTE: We must throw a NoSuchMessageException on this method since at the time of calling this method we aren't able to determine if the defaultMessage property of the resolvable is null or not.

Specified by:

getMessage in interface MessageSource

Parameters:

resolvable - value object storing attributes required to properly resolve a message

locale - the Locale in which to do the lookup

Returns:

the resolved message

Throws:

NoSuchMessageException - if the message wasn't found

See Also:

java.text.MessageFormat

getMessageInternal

protected String getMessageInternal(String code,
                                    Object[] args,
                                    Locale locale)

Resolve the given code and arguments as message in the given Locale, returning null if not found. Does not fall back to the code as default message. Invoked by getMessage methods.

Parameters:

code - the code to lookup up, such as 'calculator.noRateSet'. Users of this class are encouraged to base message names on the relevant fully qualified class name, thus avoiding conflict and ensuring maximum clarity.

args - array of arguments that will be filled in for params within the message (params look like "{0}", "{1,date}", "{2,time}" within a message), or null if none.

locale - the Locale in which to do the lookup

Returns:

the resolved message, or null if not found

See Also:

getMessage(String, Object[], String, Locale), getMessage(String, Object[], Locale), getMessage(MessageSourceResolvable, Locale), setUseCodeAsDefaultMessage(boolean)

resolveCodeWithoutArguments

protected String resolveCodeWithoutArguments(String code,
                                             Locale locale)

Subclasses can override this method to resolve a message without arguments in an optimized fashion, i.e. to resolve a message without involving a MessageFormat.

The default implementation does use MessageFormat, through delegating to the resolveCode method. Subclasses are encouraged to replace this with optimized resolution.

Unfortunately, java.text.MessageFormat is not implemented in an efficient fashion. In particular, it does not detect that a message pattern doesn't contain argument placeholders in the first place. Therefore, it's advisable to circumvent MessageFormat completely for messages without arguments.

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(java.lang.String, java.util.Locale), MessageFormat

resolveArguments

protected Object[] resolveArguments(Object[] args,
                                    Locale locale)

Search through the given array of objects, find any MessageSourceResolvable objects and resolve them.

Allows for messages to have MessageSourceResolvables as arguments.

Parameters:

args - array of arguments for a message

locale - the locale to resolve through

Returns:

an array of arguments with any MessageSourceResolvables resolved

createMessageFormat

protected MessageFormat createMessageFormat(String msg,
                                            Locale locale)

Create a MessageFormat for the given message and Locale.

This implementation creates an empty MessageFormat first, populating it with Locale and pattern afterwards, to stay compatible with J2SE 1.3.

Parameters:

msg - the message to create a MessageFormat for

locale - the Locale to create a MessageFormat for

Returns:

the MessageFormat instance

resolveCode

protected abstract MessageFormat resolveCode(String code,
                                             Locale locale)

Subclasses must implement this method to resolve a message.

Returns a MessageFormat instance rather than a message String, to allow for appropriate caching of MessageFormats in subclasses.

Subclasses are encouraged to provide optimized resolution for messages without arguments, not involving MessageFormat. See resolveCodeWithoutArguments javadoc for details.

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:

resolveCodeWithoutArguments(java.lang.String, java.util.Locale)