/*
* Copyright 2002-2008 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.text.MessageFormat;
import java.util.HashMap;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
import org.springframework.beans.factory.BeanClassLoaderAware;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;
/**
* {@link org.springframework.context.MessageSource} implementation that
* accesses resource bundles using specified basenames. This class relies
* on the underlying JDK's {@link java.util.ResourceBundle} implementation,
* in combination with the JDK's standard message parsing provided by
* {@link java.text.MessageFormat}.
*
* <p>This MessageSource caches both the accessed ResourceBundle instances and
* the generated MessageFormats for each message. It also implements rendering of
* no-arg messages without MessageFormat, as supported by the AbstractMessageSource
* base class. The caching provided by this MessageSource is significantly faster
* than the built-in caching of the <code>java.util.ResourceBundle</code> class.
*
* <p>Unfortunately, <code>java.util.ResourceBundle</code> caches loaded bundles
* forever: Reloading a bundle during VM execution is <i>not</i> possible.
* As this MessageSource relies on ResourceBundle, it faces the same limitation.
* Consider {@link ReloadableResourceBundleMessageSource} for an alternative
* that is capable of refreshing the underlying bundle files.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see #setBasenames
* @see ReloadableResourceBundleMessageSource
* @see java.util.ResourceBundle
* @see java.text.MessageFormat
*/
public class ResourceBundleMessageSource extends AbstractMessageSource implements BeanClassLoaderAware {
private String[] basenames = new String[0];
private ClassLoader bundleClassLoader;
private ClassLoader beanClassLoader = ClassUtils.getDefaultClassLoader();
/**
* Cache to hold loaded ResourceBundles.
* This Map is keyed with the bundle basename, which holds a Map that is
* keyed with the Locale and in turn holds the ResourceBundle instances.
* This allows for very efficient hash lookups, significantly faster
* than the ResourceBundle class's own cache.
*/
private final Map<String, Map<Locale, ResourceBundle>> cachedResourceBundles =
new HashMap<String, Map<Locale, ResourceBundle>>();
/**
* Cache to hold already generated MessageFormats.
* This Map is keyed with the ResourceBundle, which holds a Map that is
* keyed with the message code, which in turn holds a Map that is keyed
* with the Locale and holds the MessageFormat values. This allows for
* very efficient hash lookups without concatenated keys.
* @see #getMessageFormat
*/
private final Map<ResourceBundle, Map<String, Map<Locale, MessageFormat>>> cachedBundleMessageFormats =
new HashMap<ResourceBundle, Map<String, Map<Locale, MessageFormat>>>();
/**
* Set a single basename, following {@link java.util.ResourceBundle} conventions:
* essentially, a fully-qualified classpath location. If it doesn't contain a
* package qualifier (such as <code>org.mypackage</code>), it will be resolved
* from the classpath root.
* <p>Messages will normally be held in the "/lib" or "/classes" directory of
* a web application's WAR structure. They can also be held in jar files on
* the class path.
* <p>Note that ResourceBundle names are effectively classpath locations: As a
* consequence, the JDK's standard ResourceBundle treats dots as package separators.
* This means that "test.theme" is effectively equivalent to "test/theme",
* just like it is for programmatic <code>java.util.ResourceBundle</code> usage.
* @see #setBasenames
* @see java.util.ResourceBundle#getBundle(String)
*/
public void setBasename(String basename) {
setBasenames(new String[] {basename});
}
/**
* Set an array of basenames, each following {@link java.util.ResourceBundle}
* conventions: essentially, a fully-qualified classpath location. If it
* doesn't contain a package qualifier (such as <code>org.mypackage</code>),
* it will be resolved from the classpath root.
* <p>The associated resource bundles will be checked sequentially
* when resolving a message code. Note that message definitions in a
* <i>previous</i> resource bundle will override ones in a later bundle,
* due to the sequential lookup.
* <p>Note that ResourceBundle names are effectively classpath locations: As a
* consequence, the JDK's standard ResourceBundle treats dots as package separators.
* This means that "test.theme" is effectively equivalent to "test/theme",
* just like it is for programmatic <code>java.util.ResourceBundle</code> usage.
* @see #setBasename
* @see java.util.ResourceBundle#getBundle(String)
*/
public void setBasenames(String[] basenames) {
if (basenames != null) {
this.basenames = new String[basenames.length];
for (int i = 0; i < basenames.length; i++) {
String basename = basenames[i];
Assert.hasText(basename, "Basename must not be empty");
this.basenames[i] = basename.trim();
}
}
else {
this.basenames = new String[0];
}
}
/**
* Set the ClassLoader to load resource bundles with.
* <p>Default is the containing BeanFactory's
* {@link org.springframework.beans.factory.BeanClassLoaderAware bean ClassLoader},
* or the default ClassLoader determined by
* {@link org.springframework.util.ClassUtils#getDefaultClassLoader()}
* if not running within a BeanFactory.
*/
public void setBundleClassLoader(ClassLoader classLoader) {
this.bundleClassLoader = classLoader;
}
/**
* Return the ClassLoader to load resource bundles with.
* <p>Default is the containing BeanFactory's bean ClassLoader.
* @see #setBundleClassLoader
*/
protected ClassLoader getBundleClassLoader() {
return (this.bundleClassLoader != null ? this.bundleClassLoader : this.beanClassLoader);
}
public void setBeanClassLoader(ClassLoader classLoader) {
this.beanClassLoader = (classLoader != null ? classLoader : ClassUtils.getDefaultClassLoader());
}
/**
* Resolves the given message code as key in the registered resource bundles,
* returning the value found in the bundle as-is (without MessageFormat parsing).
*/
@Override
protected String resolveCodeWithoutArguments(String code, Locale locale) {
String result = null;
for (int i = 0; result == null && i < this.basenames.length; i++) {
ResourceBundle bundle = getResourceBundle(this.basenames[i], locale);
if (bundle != null) {
result = getStringOrNull(bundle, code);
}
}
return result;
}
/**
* Resolves the given message code as key in the registered resource bundles,
* using a cached MessageFormat instance per message code.
*/
@Override
protected MessageFormat resolveCode(String code, Locale locale) {
MessageFormat messageFormat = null;
for (int i = 0; messageFormat == null && i < this.basenames.length; i++) {
ResourceBundle bundle = getResourceBundle(this.basenames[i], locale);
if (bundle != null) {
messageFormat = getMessageFormat(bundle, code, locale);
}
}
return messageFormat;
}
/**
* Return a ResourceBundle for the given basename and code,
* fetching already generated MessageFormats from the cache.
* @param basename the basename of the ResourceBundle
* @param locale the Locale to find the ResourceBundle for
* @return the resulting ResourceBundle, or <code>null</code> if none
* found for the given basename and Locale
*/
protected ResourceBundle getResourceBundle(String basename, Locale locale) {
synchronized (this.cachedResourceBundles) {
Map<Locale, ResourceBundle> localeMap = this.cachedResourceBundles.get(basename);
if (localeMap != null) {
ResourceBundle bundle = localeMap.get(locale);
if (bundle != null) {
return bundle;
}
}
try {
ResourceBundle bundle = doGetBundle(basename, locale);
if (localeMap == null) {
localeMap = new HashMap<Locale, ResourceBundle>();
this.cachedResourceBundles.put(basename, localeMap);
}
localeMap.put(locale, bundle);
return bundle;
}
catch (MissingResourceException ex) {
if (logger.isWarnEnabled()) {
logger.warn("ResourceBundle [" + basename + "] not found for MessageSource: " + ex.getMessage());
}
// Assume bundle not found
// -> do NOT throw the exception to allow for checking parent message source.
return null;
}
}
}
/**
* Obtain the resource bundle for the given basename and Locale.
* @param basename the basename to look for
* @param locale the Locale to look for
* @return the corresponding ResourceBundle
* @throws MissingResourceException if no matching bundle could be found
* @see java.util.ResourceBundle#getBundle(String, java.util.Locale, ClassLoader)
* @see #getBundleClassLoader()
*/
protected ResourceBundle doGetBundle(String basename, Locale locale) throws MissingResourceException {
return ResourceBundle.getBundle(basename, locale, getBundleClassLoader());
}
/**
* Return a MessageFormat for the given bundle and code,
* fetching already generated MessageFormats from the cache.
* @param bundle the ResourceBundle to work on
* @param code the message code to retrieve
* @param locale the Locale to use to build the MessageFormat
* @return the resulting MessageFormat, or <code>null</code> if no message
* defined for the given code
* @throws MissingResourceException if thrown by the ResourceBundle
*/
protected MessageFormat getMessageFormat(ResourceBundle bundle, String code, Locale locale)
throws MissingResourceException {
synchronized (this.cachedBundleMessageFormats) {
Map<String, Map<Locale, MessageFormat>> codeMap = this.cachedBundleMessageFormats.get(bundle);
Map<Locale, MessageFormat> localeMap = null;
if (codeMap != null) {
localeMap = codeMap.get(code);
if (localeMap != null) {
MessageFormat result = localeMap.get(locale);
if (result != null) {
return result;
}
}
}
String msg = getStringOrNull(bundle, code);
if (msg != null) {
if (codeMap == null) {
codeMap = new HashMap<String, Map<Locale, MessageFormat>>();
this.cachedBundleMessageFormats.put(bundle, codeMap);
}
if (localeMap == null) {
localeMap = new HashMap<Locale, MessageFormat>();
codeMap.put(code, localeMap);
}
MessageFormat result = createMessageFormat(msg, locale);
localeMap.put(locale, result);
return result;
}
return null;
}
}
private String getStringOrNull(ResourceBundle bundle, String key) {
try {
return bundle.getString(key);
}
catch (MissingResourceException ex) {
// Assume key not found
// -> do NOT throw the exception to allow for checking parent message source.
return null;
}
}
/**
* Show the configuration of this MessageSource.
*/
@Override
public String toString() {
return getClass().getName() + ": basenames=[" +
StringUtils.arrayToCommaDelimitedString(this.basenames) + "]";
}
}
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