spring LocaleContextHolder 源码
spring LocaleContextHolder 代码
文件路径：/spring-context/src/main/java/org/springframework/context/i18n/LocaleContextHolder.java
/*
* Copyright 2002-2018 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.i18n;
import java.util.Locale;
import java.util.TimeZone;
import org.springframework.core.NamedInheritableThreadLocal;
import org.springframework.core.NamedThreadLocal;
import org.springframework.lang.Nullable;
/**
* Simple holder class that associates a LocaleContext instance
* with the current thread. The LocaleContext will be inherited
* by any child threads spawned by the current thread if the
* {@code inheritable} flag is set to {@code true}.
*
* <p>Used as a central holder for the current Locale in Spring,
* wherever necessary: for example, in MessageSourceAccessor.
* DispatcherServlet automatically exposes its current Locale here.
* Other applications can expose theirs too, to make classes like
* MessageSourceAccessor automatically use that Locale.
*
* @author Juergen Hoeller
* @author Nicholas Williams
* @since 1.2
* @see LocaleContext
* @see org.springframework.context.support.MessageSourceAccessor
* @see org.springframework.web.servlet.DispatcherServlet
*/
public final class LocaleContextHolder {
private static final ThreadLocal<LocaleContext> localeContextHolder =
new NamedThreadLocal<>("LocaleContext");
private static final ThreadLocal<LocaleContext> inheritableLocaleContextHolder =
new NamedInheritableThreadLocal<>("LocaleContext");
// Shared default locale at the framework level
@Nullable
private static Locale defaultLocale;
// Shared default time zone at the framework level
@Nullable
private static TimeZone defaultTimeZone;
private LocaleContextHolder() {
}
/**
* Reset the LocaleContext for the current thread.
*/
public static void resetLocaleContext() {
localeContextHolder.remove();
inheritableLocaleContextHolder.remove();
}
/**
* Associate the given LocaleContext with the current thread,
* <i>not</i> exposing it as inheritable for child threads.
* <p>The given LocaleContext may be a {@link TimeZoneAwareLocaleContext},
* containing a locale with associated time zone information.
* @param localeContext the current LocaleContext,
* or {@code null} to reset the thread-bound context
* @see SimpleLocaleContext
* @see SimpleTimeZoneAwareLocaleContext
*/
public static void setLocaleContext(@Nullable LocaleContext localeContext) {
setLocaleContext(localeContext, false);
}
/**
* Associate the given LocaleContext with the current thread.
* <p>The given LocaleContext may be a {@link TimeZoneAwareLocaleContext},
* containing a locale with associated time zone information.
* @param localeContext the current LocaleContext,
* or {@code null} to reset the thread-bound context
* @param inheritable whether to expose the LocaleContext as inheritable
* for child threads (using an {@link InheritableThreadLocal})
* @see SimpleLocaleContext
* @see SimpleTimeZoneAwareLocaleContext
*/
public static void setLocaleContext(@Nullable LocaleContext localeContext, boolean inheritable) {
if (localeContext == null) {
resetLocaleContext();
}
else {
if (inheritable) {
inheritableLocaleContextHolder.set(localeContext);
localeContextHolder.remove();
}
else {
localeContextHolder.set(localeContext);
inheritableLocaleContextHolder.remove();
}
}
}
/**
* Return the LocaleContext associated with the current thread, if any.
* @return the current LocaleContext, or {@code null} if none
*/
@Nullable
public static LocaleContext getLocaleContext() {
LocaleContext localeContext = localeContextHolder.get();
if (localeContext == null) {
localeContext = inheritableLocaleContextHolder.get();
}
return localeContext;
}
/**
* Associate the given Locale with the current thread,
* preserving any TimeZone that may have been set already.
* <p>Will implicitly create a LocaleContext for the given Locale,
* <i>not</i> exposing it as inheritable for child threads.
* @param locale the current Locale, or {@code null} to reset
* the locale part of thread-bound context
* @see #setTimeZone(TimeZone)
* @see SimpleLocaleContext#SimpleLocaleContext(Locale)
*/
public static void setLocale(@Nullable Locale locale) {
setLocale(locale, false);
}
/**
* Associate the given Locale with the current thread,
* preserving any TimeZone that may have been set already.
* <p>Will implicitly create a LocaleContext for the given Locale.
* @param locale the current Locale, or {@code null} to reset
* the locale part of thread-bound context
* @param inheritable whether to expose the LocaleContext as inheritable
* for child threads (using an {@link InheritableThreadLocal})
* @see #setTimeZone(TimeZone, boolean)
* @see SimpleLocaleContext#SimpleLocaleContext(Locale)
*/
public static void setLocale(@Nullable Locale locale, boolean inheritable) {
LocaleContext localeContext = getLocaleContext();
TimeZone timeZone = (localeContext instanceof TimeZoneAwareLocaleContext ?
((TimeZoneAwareLocaleContext) localeContext).getTimeZone() : null);
if (timeZone != null) {
localeContext = new SimpleTimeZoneAwareLocaleContext(locale, timeZone);
}
else if (locale != null) {
localeContext = new SimpleLocaleContext(locale);
}
else {
localeContext = null;
}
setLocaleContext(localeContext, inheritable);
}
/**
* Set a shared default locale at the framework level,
* as an alternative to the JVM-wide default locale.
* <p><b>NOTE:</b> This can be useful to set an application-level
* default locale which differs from the JVM-wide default locale.
* However, this requires each such application to operate against
* locally deployed Spring Framework jars. Do not deploy Spring
* as a shared library at the server level in such a scenario!
* @param locale the default locale (or {@code null} for none,
* letting lookups fall back to {@link Locale#getDefault()})
* @since 4.3.5
* @see #getLocale()
* @see Locale#getDefault()
*/
public static void setDefaultLocale(@Nullable Locale locale) {
LocaleContextHolder.defaultLocale = locale;
}
/**
* Return the Locale associated with the current thread, if any,
* or the system default Locale otherwise. This is effectively a
* replacement for {@link java.util.Locale#getDefault()},
* able to optionally respect a user-level Locale setting.
* <p>Note: This method has a fallback to the shared default Locale,
* either at the framework level or at the JVM-wide system level.
* If you'd like to check for the raw LocaleContext content
* (which may indicate no specific locale through {@code null}, use
* {@link #getLocaleContext()} and call {@link LocaleContext#getLocale()}
* @return the current Locale, or the system default Locale if no
* specific Locale has been associated with the current thread
* @see #getLocaleContext()
* @see LocaleContext#getLocale()
* @see #setDefaultLocale(Locale)
* @see java.util.Locale#getDefault()
*/
public static Locale getLocale() {
return getLocale(getLocaleContext());
}
/**
* Return the Locale associated with the given user context, if any,
* or the system default Locale otherwise. This is effectively a
* replacement for {@link java.util.Locale#getDefault()},
* able to optionally respect a user-level Locale setting.
* @param localeContext the user-level locale context to check
* @return the current Locale, or the system default Locale if no
* specific Locale has been associated with the current thread
* @since 5.0
* @see #getLocale()
* @see LocaleContext#getLocale()
* @see #setDefaultLocale(Locale)
* @see java.util.Locale#getDefault()
*/
public static Locale getLocale(@Nullable LocaleContext localeContext) {
if (localeContext != null) {
Locale locale = localeContext.getLocale();
if (locale != null) {
return locale;
}
}
return (defaultLocale != null ? defaultLocale : Locale.getDefault());
}
/**
* Associate the given TimeZone with the current thread,
* preserving any Locale that may have been set already.
* <p>Will implicitly create a LocaleContext for the given Locale,
* <i>not</i> exposing it as inheritable for child threads.
* @param timeZone the current TimeZone, or {@code null} to reset
* the time zone part of the thread-bound context
* @see #setLocale(Locale)
* @see SimpleTimeZoneAwareLocaleContext#SimpleTimeZoneAwareLocaleContext(Locale, TimeZone)
*/
public static void setTimeZone(@Nullable TimeZone timeZone) {
setTimeZone(timeZone, false);
}
/**
* Associate the given TimeZone with the current thread,
* preserving any Locale that may have been set already.
* <p>Will implicitly create a LocaleContext for the given Locale.
* @param timeZone the current TimeZone, or {@code null} to reset
* the time zone part of the thread-bound context
* @param inheritable whether to expose the LocaleContext as inheritable
* for child threads (using an {@link InheritableThreadLocal})
* @see #setLocale(Locale, boolean)
* @see SimpleTimeZoneAwareLocaleContext#SimpleTimeZoneAwareLocaleContext(Locale, TimeZone)
*/
public static void setTimeZone(@Nullable TimeZone timeZone, boolean inheritable) {
LocaleContext localeContext = getLocaleContext();
Locale locale = (localeContext != null ? localeContext.getLocale() : null);
if (timeZone != null) {
localeContext = new SimpleTimeZoneAwareLocaleContext(locale, timeZone);
}
else if (locale != null) {
localeContext = new SimpleLocaleContext(locale);
}
else {
localeContext = null;
}
setLocaleContext(localeContext, inheritable);
}
/**
* Set a shared default time zone at the framework level,
* as an alternative to the JVM-wide default time zone.
* <p><b>NOTE:</b> This can be useful to set an application-level
* default time zone which differs from the JVM-wide default time zone.
* However, this requires each such application to operate against
* locally deployed Spring Framework jars. Do not deploy Spring
* as a shared library at the server level in such a scenario!
* @param timeZone the default time zone (or {@code null} for none,
* letting lookups fall back to {@link TimeZone#getDefault()})
* @since 4.3.5
* @see #getTimeZone()
* @see TimeZone#getDefault()
*/
public static void setDefaultTimeZone(@Nullable TimeZone timeZone) {
defaultTimeZone = timeZone;
}
/**
* Return the TimeZone associated with the current thread, if any,
* or the system default TimeZone otherwise. This is effectively a
* replacement for {@link java.util.TimeZone#getDefault()},
* able to optionally respect a user-level TimeZone setting.
* <p>Note: This method has a fallback to the shared default TimeZone,
* either at the framework level or at the JVM-wide system level.
* If you'd like to check for the raw LocaleContext content
* (which may indicate no specific time zone through {@code null}), use
* {@link #getLocaleContext()} and call {@link TimeZoneAwareLocaleContext#getTimeZone()}
* after downcasting to {@link TimeZoneAwareLocaleContext}.
* @return the current TimeZone, or the system default TimeZone if no
* specific TimeZone has been associated with the current thread
* @see #getLocaleContext()
* @see TimeZoneAwareLocaleContext#getTimeZone()
* @see #setDefaultTimeZone(TimeZone)
* @see java.util.TimeZone#getDefault()
*/
public static TimeZone getTimeZone() {
return getTimeZone(getLocaleContext());
}
/**
* Return the TimeZone associated with the given user context, if any,
* or the system default TimeZone otherwise. This is effectively a
* replacement for {@link java.util.TimeZone#getDefault()},
* able to optionally respect a user-level TimeZone setting.
* @param localeContext the user-level locale context to check
* @return the current TimeZone, or the system default TimeZone if no
* specific TimeZone has been associated with the current thread
* @since 5.0
* @see #getTimeZone()
* @see TimeZoneAwareLocaleContext#getTimeZone()
* @see #setDefaultTimeZone(TimeZone)
* @see java.util.TimeZone#getDefault()
*/
public static TimeZone getTimeZone(@Nullable LocaleContext localeContext) {
if (localeContext instanceof TimeZoneAwareLocaleContext) {
TimeZone timeZone = ((TimeZoneAwareLocaleContext) localeContext).getTimeZone();
if (timeZone != null) {
return timeZone;
}
}
return (defaultTimeZone != null ? defaultTimeZone : TimeZone.getDefault());
}
}
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