/*
* Copyright 2002-2016 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.integration.expression;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
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.expression.Expression;
import org.springframework.expression.ExpressionParser;
import org.springframework.expression.spel.SpelParserConfiguration;
import org.springframework.expression.spel.standard.SpelExpressionParser;
import org.springframework.util.Assert;
import org.springframework.util.DefaultPropertiesPersister;
import org.springframework.util.PropertiesPersister;
import org.springframework.util.StringUtils;
/**
* {@link ExpressionSource} implementation that accesses resource bundles using specified basenames.
* This class uses {@link java.util.Properties} instances as its custom data structure for expressions,
* loading them via a {@link org.springframework.util.PropertiesPersister} strategy: The default
* strategy is capable of loading properties files with a specific character encoding, if desired.
*
* @author Juergen Hoeller
* @author Mark Fisher
* @author Gary Russell
* @since 2.0
* @see #setCacheSeconds
* @see #setBasenames
* @see #setDefaultEncoding
* @see #setFileEncodings
* @see #setPropertiesPersister
* @see #setResourceLoader
* @see org.springframework.util.DefaultPropertiesPersister
* @see org.springframework.core.io.DefaultResourceLoader
* @see java.util.ResourceBundle
*/
public class ReloadableResourceBundleExpressionSource implements ExpressionSource, ResourceLoaderAware {
private static final String PROPERTIES_SUFFIX = ".properties";
private static final String XML_SUFFIX = ".xml";
private static final Log logger = LogFactory.getLog(ReloadableResourceBundleExpressionSource.class);
private volatile String[] basenames = new String[0];
private volatile String defaultEncoding;
private volatile Properties fileEncodings;
private volatile boolean fallbackToSystemLocale = true;
private volatile long cacheMillis = -1;
private volatile PropertiesPersister propertiesPersister = new DefaultPropertiesPersister();
private volatile ResourceLoader resourceLoader = new DefaultResourceLoader();
/** Cache to hold filename lists per Locale */
private final Map<String, Map<Locale, List<String>>> cachedFilenames =
new HashMap<String, Map<Locale, List<String>>>();
/** Cache to hold already loaded properties per filename */
private final Map<String, PropertiesHolder> cachedProperties = new HashMap<String, PropertiesHolder>();
/** Cache to hold merged loaded properties per locale */
private final Map<Locale, PropertiesHolder> cachedMergedProperties = new HashMap<Locale, PropertiesHolder>();
private final ExpressionParser parser = new SpelExpressionParser(new SpelParserConfiguration(true, true));
/**
* Set a single basename, following the basic ResourceBundle convention of
* not specifying file extension or language codes, but referring to a Spring
* resource location: e.g. "META-INF/expressions" for "META-INF/expressions.properties",
* "META-INF/expressions_en.properties", etc.
* <p>XML properties files are also supported: .g. "META-INF/expressions" will find
* and load "META-INF/expressions.xml", "META-INF/expressions_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(new String[] { basename });
}
/**
* Set an array of basenames, each following the basic ResourceBundle convention
* of not specifying file extension or language codes, but referring to a Spring
* resource location: e.g. "META-INF/expressions" for "META-INF/expressions.properties",
* "META-INF/expressions_en.properties", etc.
* <p>XML properties files are also supported: .g. "META-INF/expressions" will find
* and load "META-INF/expressions.xml", "META-INF/expressions_en.xml", etc as well.
* <p>The associated resource bundles will be checked sequentially when resolving
* an expression key. Note that expression definitions in a <i>previous</i> 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.
* <p>Default is none, using the <code>java.util.Properties</code>
* default encoding.
* <p>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.
* <p>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. "META-INF/expressions"
* or "META-INF/expressions_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. "expressions.properties" for
* basename "expressions").
* <p>Falling back to the system Locale is the default behavior of
* <code>java.util.ResourceBundle</code>. 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.
*
* @param fallbackToSystemLocale true to fall back.
*/
public void setFallbackToSystemLocale(boolean fallbackToSystemLocale) {
this.fallbackToSystemLocale = fallbackToSystemLocale;
}
/**
* Set the number of seconds to cache loaded properties files.
* <ul>
* <li>Default is "-1", indicating to cache forever (just like
* <code>java.util.ResourceBundle</code>).
* <li>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.
* <li>A value of "0" will check the last-modified timestamp of the file on
* every expression access. <b>Do not use this in a production environment!</b>
* </ul>
*
* @param cacheSeconds The cache seconds.
*/
public void setCacheSeconds(int cacheSeconds) {
this.cacheMillis = (cacheSeconds * 1000);
}
/**
* Set the PropertiesPersister to use for parsing properties files.
* <p>The default is a DefaultPropertiesPersister.
*
* @param propertiesPersister The properties persister.
*
* @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.
* <p>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 key in the retrieved bundle files to an Expression.
*/
@Override
public Expression getExpression(String key, Locale locale) {
String expressionString = this.getExpressionString(key, locale);
if (expressionString != null) {
return this.parser.parseExpression(expressionString);
}
return null;
}
private String getExpressionString(String key, Locale locale) {
if (this.cacheMillis < 0) {
PropertiesHolder propHolder = getMergedProperties(locale);
String result = propHolder.getProperty(key);
if (result != null) {
return result;
}
}
else {
for (String basename : this.basenames) {
List<String> filenames = calculateAllFilenames(basename, locale);
for (String filename : filenames) {
PropertiesHolder propHolder = getProperties(filename);
String result = propHolder.getProperty(key);
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.
* <p>Only used when caching resource bundle contents forever, i.e.
* with cacheSeconds < 0. Therefore, merged properties are always
* cached forever.
*/
private PropertiesHolder getMergedProperties(Locale locale) {
synchronized (this.cachedMergedProperties) {
PropertiesHolder mergedHolder = this.cachedMergedProperties.get(locale);
if (mergedHolder != null) {
return mergedHolder;
}
Properties mergedProps = new Properties();
mergedHolder = new PropertiesHolder(mergedProps, -1);
for (int i = this.basenames.length - 1; i >= 0; i--) {
List<String> 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());
}
}
}
this.cachedMergedProperties.put(locale, mergedHolder);
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
*/
private List<String> calculateAllFilenames(String basename, Locale locale) {
synchronized (this.cachedFilenames) {
Map<Locale, List<String>> localeMap = this.cachedFilenames.get(basename);
if (localeMap != null) {
List<String> filenames = localeMap.get(locale);
if (filenames != null) {
return filenames;
}
}
List<String> filenames = new ArrayList<String>(7);
filenames.addAll(calculateFilenamesForLocale(basename, locale));
if (this.fallbackToSystemLocale && !locale.equals(Locale.getDefault())) {
List<String> 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.put(locale, filenames);
}
else {
localeMap = new HashMap<Locale, List<String>>();
localeMap.put(locale, filenames);
this.cachedFilenames.put(basename, localeMap);
}
return filenames;
}
}
/**
* Calculate the filenames for the given bundle basename and Locale,
* appending language code, country code, and variant code.
* E.g.: basename "expressions", Locale "de_AT_oo" -> "expressions_de_AT_OO",
* "expressions_de_AT", "expressions_de".
* <p>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
*/
private List<String> calculateFilenamesForLocale(String basename, Locale locale) {
List<String> result = new ArrayList<String>(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
*/
private PropertiesHolder getProperties(String filename) {
synchronized (this.cachedProperties) {
PropertiesHolder propHolder = this.cachedProperties.get(filename);
if (propHolder != null &&
(propHolder.getRefreshTimestamp() < 0 ||
propHolder.getRefreshTimestamp() > System.currentTimeMillis() - this.cacheMillis)) {
return propHolder;
}
return refreshProperties(filename, propHolder);
}
}
/**
* Refresh the PropertiesHolder for the given bundle filename.
* The holder can be <code>null</code> 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
*/
private 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 is 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
*/
private Properties loadProperties(Resource resource, String filename) throws IOException {
InputStream is = resource.getInputStream();
Properties props = new Properties();
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();
}
}
/**
* 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");
synchronized (this.cachedProperties) {
this.cachedProperties.clear();
}
synchronized (this.cachedMergedProperties) {
this.cachedMergedProperties.clear();
}
}
@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).
*/
private static final class PropertiesHolder {
private Properties properties;
private long fileTimestamp = -1;
private long refreshTimestamp = -1;
PropertiesHolder() {
super();
}
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);
}
}
}