org.springframework.context.support.MessageSourceResourceBundle Maven / Gradle / Ivy
/*
* Copyright 2002-2013 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.context.support;
import java.util.Enumeration;
import java.util.Locale;
import java.util.ResourceBundle;
import org.springframework.context.MessageSource;
import org.springframework.context.NoSuchMessageException;
import org.springframework.util.Assert;
/**
* Helper class that allows for accessing a Spring
* {@link org.springframework.context.MessageSource} as a {@link java.util.ResourceBundle}.
* Used for example to expose a Spring MessageSource to JSTL web views.
*
* @author Juergen Hoeller
* @since 27.02.2003
* @see org.springframework.context.MessageSource
* @see java.util.ResourceBundle
* @see org.springframework.web.servlet.support.JstlUtils#exposeLocalizationContext
*/
public class MessageSourceResourceBundle extends ResourceBundle {
private final MessageSource messageSource;
private final Locale locale;
/**
* Create a new MessageSourceResourceBundle for the given MessageSource and Locale.
* @param source the MessageSource to retrieve messages from
* @param locale the Locale to retrieve messages for
*/
public MessageSourceResourceBundle(MessageSource source, Locale locale) {
Assert.notNull(source, "MessageSource must not be null");
this.messageSource = source;
this.locale = locale;
}
/**
* Create a new MessageSourceResourceBundle for the given MessageSource and Locale.
* @param source the MessageSource to retrieve messages from
* @param locale the Locale to retrieve messages for
* @param parent the parent ResourceBundle to delegate to if no local message found
*/
public MessageSourceResourceBundle(MessageSource source, Locale locale, ResourceBundle parent) {
this(source, locale);
setParent(parent);
}
/**
* This implementation resolves the code in the MessageSource.
* Returns {@code null} if the message could not be resolved.
*/
@Override
protected Object handleGetObject(String key) {
try {
return this.messageSource.getMessage(key, null, this.locale);
}
catch (NoSuchMessageException ex) {
return null;
}
}
/**
* This implementation checks whether the target MessageSource can resolve
* a message for the given key, translating {@code NoSuchMessageException}
* accordingly. In contrast to ResourceBundle's default implementation in
* JDK 1.6, this does not rely on the capability to enumerate message keys.
*/
@Override
public boolean containsKey(String key) {
try {
this.messageSource.getMessage(key, null, this.locale);
return true;
}
catch (NoSuchMessageException ex) {
return false;
}
}
/**
* This implementation throws {@code UnsupportedOperationException},
* as a MessageSource does not allow for enumerating the defined message codes.
*/
@Override
public Enumeration getKeys() {
throw new UnsupportedOperationException("MessageSourceResourceBundle does not support enumerating its keys");
}
/**
* This implementation exposes the specified Locale for introspection
* through the standard {@code ResourceBundle.getLocale()} method.
*/
@Override
public Locale getLocale() {
return this.locale;
}
}