https://github.com/spring-projects/spring-framework: Spring Context (Spring IO)
  • Juergen Hoeller 
/*
 * Copyright 2002-2020 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
 *
 *      https://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.LinkedHashSet;
import java.util.Locale;
import java.util.Set;

import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ObjectUtils;


Abstract base class for MessageSource implementations based on resource bundle conventions, such as ResourceBundleMessageSource and ReloadableResourceBundleMessageSource. Provides common configuration methods and corresponding semantic definitions. 
Author:Juergen Hoeller
See Also:
Since:4.3
/**
 * Abstract base class for {@code MessageSource} implementations based on
 * resource bundle conventions, such as {@link ResourceBundleMessageSource}
 * and {@link ReloadableResourceBundleMessageSource}. Provides common
 * configuration methods and corresponding semantic definitions.
 *
 * @author Juergen Hoeller
 * @since 4.3
 * @see ResourceBundleMessageSource
 * @see ReloadableResourceBundleMessageSource
 */
public abstract class AbstractResourceBasedMessageSource extends AbstractMessageSource {

	private final Set<String> basenameSet = new LinkedHashSet<>(4);

	@Nullable
	private String defaultEncoding;

	private boolean fallbackToSystemLocale = true;

	@Nullable
	private Locale defaultLocale;

	private long cacheMillis = -1;


	
Set a single basename, following the basic ResourceBundle convention of not specifying file extension or language codes. The resource location format is up to the specific MessageSource implementation. 
Regular and XMl properties files are supported: e.g. "messages" will find
a "messages.properties", "messages_en.properties" etc arrangement as well
as "messages.xml", "messages_en.xml" etc.

Params:
  • basename – the single basename
See Also:
/**
	 * Set a single basename, following the basic ResourceBundle convention
	 * of not specifying file extension or language codes. The resource location
	 * format is up to the specific {@code MessageSource} implementation.
	 * <p>Regular and XMl properties files are supported: e.g. "messages" will find
	 * a "messages.properties", "messages_en.properties" etc arrangement as well
	 * as "messages.xml", "messages_en.xml" etc.
	 * @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. The resource location format is up to the specific MessageSource implementation. 
Regular and XMl properties files are supported: e.g. "messages" will find
a "messages.properties", "messages_en.properties" etc arrangement as well
as "messages.xml", "messages_en.xml" etc.

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.

Note: In contrast to addBasenames, this replaces existing entries with the given names and can therefore also be used to reset the configuration. 
Params:
  • basenames – an array of basenames
See Also:
/**
	 * Set an array of basenames, each following the basic ResourceBundle convention
	 * of not specifying file extension or language codes. The resource location
	 * format is up to the specific {@code MessageSource} implementation.
	 * <p>Regular and XMl properties files are supported: e.g. "messages" will find
	 * a "messages.properties", "messages_en.properties" etc arrangement as well
	 * as "messages.xml", "messages_en.xml" etc.
	 * <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: In contrast to {@link #addBasenames}, this replaces existing entries
	 * with the given names and can therefore also be used to reset the configuration.
	 * @param basenames an array of basenames
	 * @see #setBasename
	 * @see java.util.ResourceBundle
	 */
	public void setBasenames(String... basenames) {
		this.basenameSet.clear();
		addBasenames(basenames);
	}

	
Add the specified basenames to the existing basename configuration.

Note: If a given basename already exists, the position of its entry
will remain as in the original set. New entries will be added at the
end of the list, to be searched after existing basenames.

See Also:
Since:4.3
/**
	 * Add the specified basenames to the existing basename configuration.
	 * <p>Note: If a given basename already exists, the position of its entry
	 * will remain as in the original set. New entries will be added at the
	 * end of the list, to be searched after existing basenames.
	 * @since 4.3
	 * @see #setBasenames
	 * @see java.util.ResourceBundle
	 */
	public void addBasenames(String... basenames) {
		if (!ObjectUtils.isEmpty(basenames)) {
			for (String basename : basenames) {
				Assert.hasText(basename, "Basename must not be empty");
				this.basenameSet.add(basename.trim());
			}
		}
	}

	
Return this MessageSource's basename set, containing entries in the order of registration. 
Calling code may introspect this set as well as add or remove entries.

See Also:
Since:4.3
/**
	 * Return this {@code MessageSource}'s basename set, containing entries
	 * in the order of registration.
	 * <p>Calling code may introspect this set as well as add or remove entries.
	 * @since 4.3
	 * @see #addBasenames
	 */
	public Set<String> getBasenameSet() {
		return this.basenameSet;
	}

	
Set the default charset to use for parsing properties files.
Used if no file-specific charset is specified for a file.

The effective default is the java.util.Properties default encoding: ISO-8859-1. A null value indicates the platform default encoding. 
Only applies to classic properties files, not to XML files.

Params:
  • defaultEncoding – the default charset
/**
	 * Set the default charset to use for parsing properties files.
	 * Used if no file-specific charset is specified for a file.
	 * <p>The effective default is the {@code java.util.Properties}
	 * default encoding: ISO-8859-1. A {@code null} value indicates
	 * the platform default encoding.
	 * <p>Only applies to classic properties files, not to XML files.
	 * @param defaultEncoding the default charset
	 */
	public void setDefaultEncoding(@Nullable String defaultEncoding) {
		this.defaultEncoding = defaultEncoding;
	}

	
Return the default charset to use for parsing properties files, if any.

Since:4.3
/**
	 * Return the default charset to use for parsing properties files, if any.
	 * @since 4.3
	 */
	@Nullable
	protected String getDefaultEncoding() {
		return this.defaultEncoding;
	}

	
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 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. 
See Also:
/**
	 * 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").
	 * <p>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.
	 * @see #setDefaultLocale
	 */
	public void setFallbackToSystemLocale(boolean fallbackToSystemLocale) {
		this.fallbackToSystemLocale = fallbackToSystemLocale;
	}

	
Return whether to fall back to the system Locale if no files for a specific
Locale have been found.

Since:4.3
Deprecated:as of 5.2.2, in favor of getDefaultLocale()
/**
	 * Return whether to fall back to the system Locale if no files for a specific
	 * Locale have been found.
	 * @since 4.3
	 * @deprecated as of 5.2.2, in favor of {@link #getDefaultLocale()}
	 */
	@Deprecated
	protected boolean isFallbackToSystemLocale() {
		return this.fallbackToSystemLocale;
	}

	
Specify a default Locale to fall back to, as an alternative to falling back
to the system Locale.

Default is to fall back to the system Locale. You may override this with a locally specified default Locale here, or enforce no fallback locale at all through disabling "fallbackToSystemLocale". 
See Also:
Since:5.2.2
/**
	 * Specify a default Locale to fall back to, as an alternative to falling back
	 * to the system Locale.
	 * <p>Default is to fall back to the system Locale. You may override this with
	 * a locally specified default Locale here, or enforce no fallback locale at all
	 * through disabling {@link #setFallbackToSystemLocale "fallbackToSystemLocale"}.
	 * @since 5.2.2
	 * @see #setFallbackToSystemLocale
	 * @see #getDefaultLocale()
	 */
	public void setDefaultLocale(@Nullable Locale defaultLocale) {
		this.defaultLocale = defaultLocale;
	}

	
Determine a default Locale to fall back to: either a locally specified default Locale or the system Locale, or null for no fallback locale at all. 
See Also:
Since:5.2.2
/**
	 * Determine a default Locale to fall back to: either a locally specified default
	 * Locale or the system Locale, or {@code null} for no fallback locale at all.
	 * @since 5.2.2
	 * @see #setDefaultLocale
	 * @see #setFallbackToSystemLocale
	 * @see Locale#getDefault()
	 */
	@Nullable
	protected Locale getDefaultLocale() {
		if (this.defaultLocale != null) {
			return this.defaultLocale;
		}
		if (this.fallbackToSystemLocale) {
			return Locale.getDefault();
		}
		return null;
	}

	
Set the number of seconds to cache loaded properties files.

    

  • Default is "-1", indicating to cache forever (matching the default behavior of java.util.ResourceBundle). Note that this constant follows Spring conventions, not Control.getTimeToLive. 
  • 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!



Note that depending on your ClassLoader, expiration might not work reliably
since the ClassLoader may hold on to a cached version of the bundle file. Prefer ReloadableResourceBundleMessageSource over ResourceBundleMessageSource in such a scenario, in combination with a non-classpath location. 
/**
	 * Set the number of seconds to cache loaded properties files.
	 * <ul>
	 * <li>Default is "-1", indicating to cache forever (matching the default behavior
	 * of {@code java.util.ResourceBundle}). Note that this constant follows Spring
	 * conventions, not {@link java.util.ResourceBundle.Control#getTimeToLive}.
	 * <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 message access. <b>Do not use this in a production environment!</b>
	 * </ul>
	 * <p><b>Note that depending on your ClassLoader, expiration might not work reliably
	 * since the ClassLoader may hold on to a cached version of the bundle file.</b>
	 * Prefer {@link ReloadableResourceBundleMessageSource} over
	 * {@link ResourceBundleMessageSource} in such a scenario, in combination with
	 * a non-classpath location.
	 */
	public void setCacheSeconds(int cacheSeconds) {
		this.cacheMillis = cacheSeconds * 1000L;
	}

	
Set the number of milliseconds to cache loaded properties files. Note that it is common to set seconds instead: setCacheSeconds. 
    

  • Default is "-1", indicating to cache forever (matching the default behavior of java.util.ResourceBundle). Note that this constant follows Spring conventions, not Control.getTimeToLive. 
  • A positive number will cache loaded properties files for the given
number of milliseconds. 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!



See Also:
Since:4.3
/**
	 * Set the number of milliseconds to cache loaded properties files.
	 * Note that it is common to set seconds instead: {@link #setCacheSeconds}.
	 * <ul>
	 * <li>Default is "-1", indicating to cache forever (matching the default behavior
	 * of {@code java.util.ResourceBundle}). Note that this constant follows Spring
	 * conventions, not {@link java.util.ResourceBundle.Control#getTimeToLive}.
	 * <li>A positive number will cache loaded properties files for the given
	 * number of milliseconds. 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 message access. <b>Do not use this in a production environment!</b>
	 * </ul>
	 * @since 4.3
	 * @see #setCacheSeconds
	 */
	public void setCacheMillis(long cacheMillis) {
		this.cacheMillis = cacheMillis;
	}

	
Return the number of milliseconds to cache loaded properties files.

Since:4.3
/**
	 * Return the number of milliseconds to cache loaded properties files.
	 * @since 4.3
	 */
	protected long getCacheMillis() {
		return this.cacheMillis;
	}

}