Java tutorial
/* * 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.ui.context.support; import java.util.Map; import java.util.concurrent.ConcurrentHashMap; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.springframework.beans.factory.BeanClassLoaderAware; import org.springframework.context.HierarchicalMessageSource; import org.springframework.context.MessageSource; import org.springframework.context.support.ResourceBundleMessageSource; import org.springframework.lang.Nullable; import org.springframework.ui.context.HierarchicalThemeSource; import org.springframework.ui.context.Theme; import org.springframework.ui.context.ThemeSource; /** * {@link ThemeSource} implementation that looks up an individual * {@link java.util.ResourceBundle} per theme. The theme name gets * interpreted as ResourceBundle basename, supporting a common * basename prefix for all themes. * * @author Jean-Pierre Pawlak * @author Juergen Hoeller * @see #setBasenamePrefix * @see java.util.ResourceBundle * @see org.springframework.context.support.ResourceBundleMessageSource */ public class ResourceBundleThemeSource implements HierarchicalThemeSource, BeanClassLoaderAware { protected final Log logger = LogFactory.getLog(getClass()); @Nullable private ThemeSource parentThemeSource; private String basenamePrefix = ""; @Nullable private String defaultEncoding; @Nullable private Boolean fallbackToSystemLocale; @Nullable private ClassLoader beanClassLoader; /** Map from theme name to Theme instance. */ private final Map<String, Theme> themeCache = new ConcurrentHashMap<>(); @Override public void setParentThemeSource(@Nullable ThemeSource parent) { this.parentThemeSource = parent; // Update existing Theme objects. // Usually there shouldn't be any at the time of this call. synchronized (this.themeCache) { for (Theme theme : this.themeCache.values()) { initParent(theme); } } } @Override @Nullable public ThemeSource getParentThemeSource() { return this.parentThemeSource; } /** * Set the prefix that gets applied to the ResourceBundle basenames, * i.e. the theme names. * E.g.: basenamePrefix="test.", themeName="theme" -> basename="test.theme". * <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} usage. * @see java.util.ResourceBundle#getBundle(String) */ public void setBasenamePrefix(@Nullable String basenamePrefix) { this.basenamePrefix = (basenamePrefix != null ? basenamePrefix : ""); } /** * Set the default charset to use for parsing resource bundle files. * <p>{@link ResourceBundleMessageSource}'s default is the * {@code java.util.ResourceBundle} default encoding: ISO-8859-1. * @since 4.2 * @see ResourceBundleMessageSource#setDefaultEncoding */ public void setDefaultEncoding(@Nullable String defaultEncoding) { this.defaultEncoding = defaultEncoding; } /** * Set whether to fall back to the system Locale if no files for a * specific Locale have been found. * <p>{@link ResourceBundleMessageSource}'s default is "true". * @since 4.2 * @see ResourceBundleMessageSource#setFallbackToSystemLocale */ public void setFallbackToSystemLocale(boolean fallbackToSystemLocale) { this.fallbackToSystemLocale = fallbackToSystemLocale; } @Override public void setBeanClassLoader(@Nullable ClassLoader beanClassLoader) { this.beanClassLoader = beanClassLoader; } /** * This implementation returns a SimpleTheme instance, holding a * ResourceBundle-based MessageSource whose basename corresponds to * the given theme name (prefixed by the configured "basenamePrefix"). * <p>SimpleTheme instances are cached per theme name. Use a reloadable * MessageSource if themes should reflect changes to the underlying files. * @see #setBasenamePrefix * @see #createMessageSource */ @Override @Nullable public Theme getTheme(String themeName) { Theme theme = this.themeCache.get(themeName); if (theme == null) { synchronized (this.themeCache) { theme = this.themeCache.get(themeName); if (theme == null) { String basename = this.basenamePrefix + themeName; MessageSource messageSource = createMessageSource(basename); theme = new SimpleTheme(themeName, messageSource); initParent(theme); this.themeCache.put(themeName, theme); if (logger.isDebugEnabled()) { logger.debug("Theme created: name '" + themeName + "', basename [" + basename + "]"); } } } } return theme; } /** * Create a MessageSource for the given basename, * to be used as MessageSource for the corresponding theme. * <p>Default implementation creates a ResourceBundleMessageSource. * for the given basename. A subclass could create a specifically * configured ReloadableResourceBundleMessageSource, for example. * @param basename the basename to create a MessageSource for * @return the MessageSource * @see org.springframework.context.support.ResourceBundleMessageSource * @see org.springframework.context.support.ReloadableResourceBundleMessageSource */ protected MessageSource createMessageSource(String basename) { ResourceBundleMessageSource messageSource = new ResourceBundleMessageSource(); messageSource.setBasename(basename); if (this.defaultEncoding != null) { messageSource.setDefaultEncoding(this.defaultEncoding); } if (this.fallbackToSystemLocale != null) { messageSource.setFallbackToSystemLocale(this.fallbackToSystemLocale); } if (this.beanClassLoader != null) { messageSource.setBeanClassLoader(this.beanClassLoader); } return messageSource; } /** * Initialize the MessageSource of the given theme with the * one from the corresponding parent of this ThemeSource. * @param theme the Theme to (re-)initialize */ protected void initParent(Theme theme) { if (theme.getMessageSource() instanceof HierarchicalMessageSource) { HierarchicalMessageSource messageSource = (HierarchicalMessageSource) theme.getMessageSource(); if (getParentThemeSource() != null && messageSource.getParentMessageSource() == null) { Theme parentTheme = getParentThemeSource().getTheme(theme.getName()); if (parentTheme != null) { messageSource.setParentMessageSource(parentTheme.getMessageSource()); } } } } }