org.springframework.context.support.ReloadableResourceBundleMessageSource Maven / Gradle / Ivy
Show all versions of spring-context Show documentation
/*
* Copyright 2002-2015 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.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.text.MessageFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.locks.ReentrantLock;
import org.springframework.context.ResourceLoaderAware;
import org.springframework.core.io.DefaultResourceLoader;
import org.springframework.core.io.Resource;
import org.springframework.core.io.ResourceLoader;
import org.springframework.util.Assert;
import org.springframework.util.DefaultPropertiesPersister;
import org.springframework.util.PropertiesPersister;
import org.springframework.util.StringUtils;
/**
* Spring-specific {@link org.springframework.context.MessageSource} implementation
* that accesses resource bundles using specified basenames, participating in the
* Spring {@link org.springframework.context.ApplicationContext}'s resource loading.
*
* In contrast to the JDK-based {@link ResourceBundleMessageSource}, this class uses
* {@link java.util.Properties} instances as its custom data structure for messages,
* loading them via a {@link org.springframework.util.PropertiesPersister} strategy
* from Spring {@link Resource} handles. This strategy is not only capable of
* reloading files based on timestamp changes, but also of loading properties files
* with a specific character encoding. It will detect XML property files as well.
*
*
In contrast to {@link ResourceBundleMessageSource}, this class supports
* reloading of properties files through the {@link #setCacheSeconds "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 {@link #setBasenames "basenames"} property
* are treated in a slightly different fashion than the "basenames" property of
* {@link 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
* {@link ResourceBundleMessageSource}, which builds on {@link java.util.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
* {@link org.springframework.context.ApplicationContext}: It will use a
* {@link org.springframework.core.io.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 #setCacheSeconds
* @see #setBasenames
* @see #setDefaultEncoding
* @see #setFileEncodings
* @see #setPropertiesPersister
* @see #setResourceLoader
* @see org.springframework.util.DefaultPropertiesPersister
* @see org.springframework.core.io.DefaultResourceLoader
* @see ResourceBundleMessageSource
* @see java.util.ResourceBundle
*/
public class ReloadableResourceBundleMessageSource extends AbstractMessageSource implements ResourceLoaderAware {
private static final String PROPERTIES_SUFFIX = ".properties";
private static final String XML_SUFFIX = ".xml";
private String[] basenames = new String[0];
private String defaultEncoding;
private Properties fileEncodings;
private boolean fallbackToSystemLocale = true;
private long cacheMillis = -1;
private boolean concurrentRefresh = true;
private PropertiesPersister propertiesPersister = new DefaultPropertiesPersister();
private ResourceLoader resourceLoader = new DefaultResourceLoader();
/** Cache to hold filename lists per Locale */
private final ConcurrentMap>> cachedFilenames =
new ConcurrentHashMap>>();
/** Cache to hold already loaded properties per filename */
private final ConcurrentMap cachedProperties =
new ConcurrentHashMap();
/** Cache to hold merged loaded properties per locale */
private final ConcurrentMap cachedMergedProperties =
new ConcurrentHashMap();
/**
* Set a single basename, following the basic ResourceBundle convention of
* not specifying file extension or language codes, but in contrast to
* {@link 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.
* @param basename the single basename
* @see #setBasenames
* @see org.springframework.core.io.ResourceEditor
* @see java.util.ResourceBundle
*/
public void setBasename(String basename) {
setBasenames(basename);
}
/**
* Set an array of basenames, each following the basic ResourceBundle convention
* of not specifying file extension or language codes, but in contrast to
* {@link 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.
* @param basenames an array of basenames
* @see #setBasename
* @see java.util.ResourceBundle
*/
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 default charset to use for parsing properties files.
* Used if no file-specific charset is specified for a file.
*
Default is none, using the {@code java.util.Properties}
* default encoding: ISO-8859-1.
*
Only applies to classic properties files, not to XML files.
* @param defaultEncoding the default charset
* @see #setFileEncodings
* @see org.springframework.util.PropertiesPersister#load
*/
public void setDefaultEncoding(String defaultEncoding) {
this.defaultEncoding = defaultEncoding;
}
/**
* Set per-file charsets to use for parsing properties files.
*
Only applies to classic properties files, not to XML files.
* @param 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 #setBasenames
* @see org.springframework.util.PropertiesPersister#load
*/
public void setFileEncodings(Properties fileEncodings) {
this.fileEncodings = fileEncodings;
}
/**
* 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
* {@code 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 setFallbackToSystemLocale(boolean fallbackToSystemLocale) {
this.fallbackToSystemLocale = fallbackToSystemLocale;
}
/**
* Set the number of seconds to cache loaded properties files.
*
* - Default is "-1", indicating to cache forever (just like
* {@code 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 setCacheSeconds(int cacheSeconds) {
this.cacheMillis = (cacheSeconds * 1000);
}
/**
* Specify whether to allow for concurrent refresh behavior, i.e. one thread
* locked in a refresh attempt for a specific cached properties file whereas
* other threads keep returning the old properties for the time being, until
* the refresh attempt has completed.
* Default is "true": This behavior is new as of Spring Framework 4.1,
* minimizing contention between threads. If you prefer the old behavior,
* i.e. to fully block on refresh, switch this flag to "false".
* @see #setCacheSeconds
*/
public void setConcurrentRefresh(boolean concurrentRefresh) {
this.concurrentRefresh = concurrentRefresh;
}
/**
* Set the PropertiesPersister to use for parsing properties files.
*
The default is a DefaultPropertiesPersister.
* @see org.springframework.util.DefaultPropertiesPersister
*/
public void setPropertiesPersister(PropertiesPersister propertiesPersister) {
this.propertiesPersister =
(propertiesPersister != null ? propertiesPersister : new DefaultPropertiesPersister());
}
/**
* 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.
* @see org.springframework.core.io.DefaultResourceLoader
* @see org.springframework.context.ResourceLoaderAware
*/
@Override
public void setResourceLoader(ResourceLoader resourceLoader) {
this.resourceLoader = (resourceLoader != null ? resourceLoader : new DefaultResourceLoader());
}
/**
* Resolves the given message code as key in the retrieved bundle files,
* returning the value found in the bundle as-is (without MessageFormat parsing).
*/
@Override
protected String resolveCodeWithoutArguments(String code, Locale locale) {
if (this.cacheMillis < 0) {
PropertiesHolder propHolder = getMergedProperties(locale);
String result = propHolder.getProperty(code);
if (result != null) {
return result;
}
}
else {
for (String basename : this.basenames) {
List filenames = calculateAllFilenames(basename, locale);
for (String filename : filenames) {
PropertiesHolder propHolder = getProperties(filename);
String result = propHolder.getProperty(code);
if (result != null) {
return result;
}
}
}
}
return null;
}
/**
* Resolves the given message code as key in the retrieved bundle files,
* using a cached MessageFormat instance per message code.
*/
@Override
protected MessageFormat resolveCode(String code, Locale locale) {
if (this.cacheMillis < 0) {
PropertiesHolder propHolder = getMergedProperties(locale);
MessageFormat result = propHolder.getMessageFormat(code, locale);
if (result != null) {
return result;
}
}
else {
for (String basename : this.basenames) {
List filenames = calculateAllFilenames(basename, locale);
for (String filename : filenames) {
PropertiesHolder propHolder = getProperties(filename);
MessageFormat result = propHolder.getMessageFormat(code, locale);
if (result != null) {
return result;
}
}
}
}
return null;
}
/**
* 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 PropertiesHolder getMergedProperties(Locale locale) {
PropertiesHolder mergedHolder = this.cachedMergedProperties.get(locale);
if (mergedHolder != null) {
return mergedHolder;
}
Properties mergedProps = newProperties();
mergedHolder = new PropertiesHolder(mergedProps, -1);
for (int i = this.basenames.length - 1; i >= 0; i--) {
List filenames = calculateAllFilenames(this.basenames[i], locale);
for (int j = filenames.size() - 1; j >= 0; j--) {
String filename = filenames.get(j);
PropertiesHolder propHolder = getProperties(filename);
if (propHolder.getProperties() != null) {
mergedProps.putAll(propHolder.getProperties());
}
}
}
PropertiesHolder existing = this.cachedMergedProperties.putIfAbsent(locale, mergedHolder);
if (existing != null) {
mergedHolder = existing;
}
return mergedHolder;
}
/**
* 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.
* @param basename the basename of the bundle
* @param locale the locale
* @return the List of filenames to check
* @see #setFallbackToSystemLocale
* @see #calculateFilenamesForLocale
*/
protected List calculateAllFilenames(String basename, Locale locale) {
Map> localeMap = this.cachedFilenames.get(basename);
if (localeMap != null) {
List filenames = localeMap.get(locale);
if (filenames != null) {
return filenames;
}
}
List filenames = new ArrayList(7);
filenames.addAll(calculateFilenamesForLocale(basename, locale));
if (this.fallbackToSystemLocale && !locale.equals(Locale.getDefault())) {
List fallbackFilenames = calculateFilenamesForLocale(basename, Locale.getDefault());
for (String fallbackFilename : fallbackFilenames) {
if (!filenames.contains(fallbackFilename)) {
// Entry for fallback locale that isn't already in filenames list.
filenames.add(fallbackFilename);
}
}
}
filenames.add(basename);
if (localeMap == null) {
localeMap = new ConcurrentHashMap>();
Map> existing = this.cachedFilenames.putIfAbsent(basename, localeMap);
if (existing != null) {
localeMap = existing;
}
}
localeMap.put(locale, filenames);
return filenames;
}
/**
* 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 {@link java.util.Locale#toString()}.
* @param basename the basename of the bundle
* @param locale the locale
* @return the List of filenames to check
*/
protected List calculateFilenamesForLocale(String basename, Locale locale) {
List result = new ArrayList(3);
String language = locale.getLanguage();
String country = locale.getCountry();
String variant = locale.getVariant();
StringBuilder temp = new StringBuilder(basename);
temp.append('_');
if (language.length() > 0) {
temp.append(language);
result.add(0, temp.toString());
}
temp.append('_');
if (country.length() > 0) {
temp.append(country);
result.add(0, temp.toString());
}
if (variant.length() > 0 && (language.length() > 0 || country.length() > 0)) {
temp.append('_').append(variant);
result.add(0, temp.toString());
}
return result;
}
/**
* Get a PropertiesHolder for the given filename, either from the
* cache or freshly loaded.
* @param filename the bundle filename (basename + Locale)
* @return the current PropertiesHolder for the bundle
*/
protected PropertiesHolder getProperties(String filename) {
PropertiesHolder propHolder = this.cachedProperties.get(filename);
long originalTimestamp = -2;
if (propHolder != null) {
originalTimestamp = propHolder.getRefreshTimestamp();
if (originalTimestamp == -1 || originalTimestamp > System.currentTimeMillis() - this.cacheMillis) {
// Up to date
return propHolder;
}
}
else {
propHolder = new PropertiesHolder();
PropertiesHolder existingHolder = this.cachedProperties.putIfAbsent(filename, propHolder);
if (existingHolder != null) {
propHolder = existingHolder;
}
}
// At this point, we need to refresh...
if (this.concurrentRefresh && propHolder.getRefreshTimestamp() >= 0) {
// A populated but stale holder -> could keep using it.
if (!propHolder.refreshLock.tryLock()) {
// Getting refreshed by another thread already ->
// let's return the existing properties for the time being.
return propHolder;
}
}
else {
propHolder.refreshLock.lock();
}
try {
PropertiesHolder existingHolder = this.cachedProperties.get(filename);
if (existingHolder != null && existingHolder.getRefreshTimestamp() > originalTimestamp) {
return existingHolder;
}
return refreshProperties(filename, propHolder);
}
finally {
propHolder.refreshLock.unlock();
}
}
/**
* Refresh the PropertiesHolder for the given bundle filename.
* The holder can be {@code null} if not cached before, or a timed-out cache entry
* (potentially getting re-validated against the current last-modified timestamp).
* @param filename the bundle filename (basename + Locale)
* @param propHolder the current PropertiesHolder for the bundle
*/
protected PropertiesHolder refreshProperties(String filename, PropertiesHolder propHolder) {
long refreshTimestamp = (this.cacheMillis < 0 ? -1 : System.currentTimeMillis());
Resource resource = this.resourceLoader.getResource(filename + PROPERTIES_SUFFIX);
if (!resource.exists()) {
resource = this.resourceLoader.getResource(filename + XML_SUFFIX);
}
if (resource.exists()) {
long fileTimestamp = -1;
if (this.cacheMillis >= 0) {
// Last-modified timestamp of file will just be read if caching with timeout.
try {
fileTimestamp = resource.lastModified();
if (propHolder != null && propHolder.getFileTimestamp() == fileTimestamp) {
if (logger.isDebugEnabled()) {
logger.debug("Re-caching properties for filename [" + filename + "] - file hasn't been modified");
}
propHolder.setRefreshTimestamp(refreshTimestamp);
return propHolder;
}
}
catch (IOException ex) {
// Probably a class path resource: cache it forever.
if (logger.isDebugEnabled()) {
logger.debug(resource + " could not be resolved in the file system - assuming that it hasn't changed", ex);
}
fileTimestamp = -1;
}
}
try {
Properties props = loadProperties(resource, filename);
propHolder = new PropertiesHolder(props, fileTimestamp);
}
catch (IOException ex) {
if (logger.isWarnEnabled()) {
logger.warn("Could not parse properties file [" + resource.getFilename() + "]", ex);
}
// Empty holder representing "not valid".
propHolder = new PropertiesHolder();
}
}
else {
// Resource does not exist.
if (logger.isDebugEnabled()) {
logger.debug("No properties file found for [" + filename + "] - neither plain properties nor XML");
}
// Empty holder representing "not found".
propHolder = new PropertiesHolder();
}
propHolder.setRefreshTimestamp(refreshTimestamp);
this.cachedProperties.put(filename, propHolder);
return propHolder;
}
/**
* Load the properties from the given resource.
* @param resource the resource to load from
* @param filename the original bundle filename (basename + Locale)
* @return the populated Properties instance
* @throws IOException if properties loading failed
*/
protected Properties loadProperties(Resource resource, String filename) throws IOException {
InputStream is = resource.getInputStream();
Properties props = newProperties();
try {
if (resource.getFilename().endsWith(XML_SUFFIX)) {
if (logger.isDebugEnabled()) {
logger.debug("Loading properties [" + resource.getFilename() + "]");
}
this.propertiesPersister.loadFromXml(props, is);
}
else {
String encoding = null;
if (this.fileEncodings != null) {
encoding = this.fileEncodings.getProperty(filename);
}
if (encoding == null) {
encoding = this.defaultEncoding;
}
if (encoding != null) {
if (logger.isDebugEnabled()) {
logger.debug("Loading properties [" + resource.getFilename() + "] with encoding '" + encoding + "'");
}
this.propertiesPersister.load(props, new InputStreamReader(is, encoding));
}
else {
if (logger.isDebugEnabled()) {
logger.debug("Loading properties [" + resource.getFilename() + "]");
}
this.propertiesPersister.load(props, is);
}
}
return props;
}
finally {
is.close();
}
}
/**
* Template method for creating a plain new {@link Properties} instance.
* The default implementation simply calls {@link Properties#Properties()}.
* Allows for returning a custom {@link Properties} extension in subclasses.
* Overriding methods should just instantiate a custom {@link Properties} subclass,
* with no further initialization or population to be performed at that point.
* @return a plain Properties instance
* @since 4.2
*/
protected Properties newProperties() {
return new Properties();
}
/**
* Clear the resource bundle cache.
* Subsequent resolve calls will lead to reloading of the properties files.
*/
public void clearCache() {
logger.debug("Clearing entire resource bundle cache");
this.cachedProperties.clear();
this.cachedMergedProperties.clear();
}
/**
* Clear the resource bundle caches of this MessageSource and all its ancestors.
* @see #clearCache
*/
public void clearCacheIncludingAncestors() {
clearCache();
if (getParentMessageSource() instanceof ReloadableResourceBundleMessageSource) {
((ReloadableResourceBundleMessageSource) getParentMessageSource()).clearCacheIncludingAncestors();
}
}
@Override
public String toString() {
return getClass().getName() + ": basenames=[" + StringUtils.arrayToCommaDelimitedString(this.basenames) + "]";
}
/**
* PropertiesHolder for caching.
* Stores the last-modified timestamp of the source file for efficient
* change detection, and the timestamp of the last refresh attempt
* (updated every time the cache entry gets re-validated).
*/
protected class PropertiesHolder {
private final Properties properties;
private final long fileTimestamp;
private volatile long refreshTimestamp = -2;
private final ReentrantLock refreshLock = new ReentrantLock();
/** Cache to hold already generated MessageFormats per message code */
private final ConcurrentMap> cachedMessageFormats =
new ConcurrentHashMap>();
public PropertiesHolder() {
this.properties = null;
this.fileTimestamp = -1;
}
public PropertiesHolder(Properties properties, long fileTimestamp) {
this.properties = properties;
this.fileTimestamp = fileTimestamp;
}
public Properties getProperties() {
return this.properties;
}
public long getFileTimestamp() {
return this.fileTimestamp;
}
public void setRefreshTimestamp(long refreshTimestamp) {
this.refreshTimestamp = refreshTimestamp;
}
public long getRefreshTimestamp() {
return this.refreshTimestamp;
}
public String getProperty(String code) {
if (this.properties == null) {
return null;
}
return this.properties.getProperty(code);
}
public MessageFormat getMessageFormat(String code, Locale locale) {
if (this.properties == null) {
return null;
}
Map localeMap = this.cachedMessageFormats.get(code);
if (localeMap != null) {
MessageFormat result = localeMap.get(locale);
if (result != null) {
return result;
}
}
String msg = this.properties.getProperty(code);
if (msg != null) {
if (localeMap == null) {
localeMap = new ConcurrentHashMap();
Map existing = this.cachedMessageFormats.putIfAbsent(code, localeMap);
if (existing != null) {
localeMap = existing;
}
}
MessageFormat result = createMessageFormat(msg, locale);
localeMap.put(locale, result);
return result;
}
return null;
}
}
}