Spring Framework example source code file (ResourceBundleViewResolver.java)

This example Spring Framework source code file (ResourceBundleViewResolver.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Spring Framework tags/keywords

beanfactory, beanfactory, beansexception, classloader, genericwebapplicationcontext, locale, locale, map, propertiesbeandefinitionreader, resourcebundle, resourcebundle, string, string, util, view

The Spring Framework ResourceBundleViewResolver.java source code

/*
 * Copyright 2002-2007 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.web.servlet.view;

import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.support.PropertiesBeanDefinitionReader;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.core.Ordered;
import org.springframework.web.context.support.GenericWebApplicationContext;
import org.springframework.web.servlet.View;

/**
 * {@link org.springframework.web.servlet.ViewResolver} implementation 
 * that uses bean definitions in a {@link ResourceBundle}, specified by
 * the bundle basename.
 * 
 * <p>The bundle is typically defined in a properties file, located in
 * the class path. The default bundle basename is "views".
 *
 * <p>This ViewResolver supports localized view definitions,
 * using the default support of {@link java.util.PropertyResourceBundle}.
 * For example, the basename "views" will be resolved as class path resources
 * "views_de_AT.properties", "views_de.properties", "views.properties" -
 * for a given Locale "de_AT".
 *
 * <p>Note: this ViewResolver implements the {@link Ordered}
 * interface to allow for flexible participation in <code>ViewResolver
 * chaining. For example, some special views could be defined via this
 * <code>ViewResolver (giving it 0 as "order" value), while all
 * remaining views could be resolved by a {@link UrlBasedViewResolver}.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see java.util.ResourceBundle#getBundle
 * @see java.util.PropertyResourceBundle
 * @see UrlBasedViewResolver
 */
public class ResourceBundleViewResolver extends AbstractCachingViewResolver implements Ordered, DisposableBean {

	/** The default basename if no other basename is supplied. */
	public final static String DEFAULT_BASENAME = "views";


	private int order = Integer.MAX_VALUE;  // default: same as non-Ordered

	private String[] basenames = new String[] {DEFAULT_BASENAME};

	private ClassLoader bundleClassLoader = Thread.currentThread().getContextClassLoader();

	private String defaultParentView;

	private Locale[] localesToInitialize;

	/* Locale -> BeanFactory */
	private final Map localeCache = new HashMap();

	/* List of ResourceBundle -> BeanFactory */
	private final Map bundleCache = new HashMap();


	public void setOrder(int order) {
		this.order = order;
	}

	public int getOrder() {
		return this.order;
	}

	/**
	 * Set a single basename, following {@link java.util.ResourceBundle} conventions.
	 * The default is "views".
	 * <p>ResourceBundle supports different suffixes. For example,
	 * a base name of "views" might map to <code>ResourceBundle files
	 * "views", "views_en_au" and "views_de".
	 * <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 #setBasenames
	 * @see java.util.ResourceBundle#getBundle(String)
	 */
	public void setBasename(String basename) {
		setBasenames(new String[] {basename});
	}

	/**
	 * Set an array of basenames, each following {@link java.util.ResourceBundle}
	 * conventions. The default is a single basename "views".
	 * <p>ResourceBundle supports different suffixes. For example,
	 * a base name of "views" might map to <code>ResourceBundle files
	 * "views", "views_en_au" and "views_de".
	 * <p>The associated resource bundles will be checked sequentially
	 * when resolving a message code. Note that message definitions in a
	 * <i>previous resource bundle will override ones in a later bundle,
	 * due to the sequential lookup.
	 * <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 #setBasename
	 * @see java.util.ResourceBundle#getBundle(String)
	 */
	public void setBasenames(String[] basenames) {
		this.basenames = basenames;
	}

	/**
	 * Set the {@link ClassLoader} to load resource bundles with.
	 * Default is the thread context <code>ClassLoader.
	 */
	public void setBundleClassLoader(ClassLoader classLoader) {
		this.bundleClassLoader = classLoader;
	}

	/**
	 * Return the {@link ClassLoader} to load resource bundles with.
	 * <p>Default is the specified bundle ClassLoader,
	 * usually the thread context <code>ClassLoader.
	 */
	protected ClassLoader getBundleClassLoader() {
		return this.bundleClassLoader;
	}

	/**
	 * Set the default parent for views defined in the <code>ResourceBundle.
	 * <p>This avoids repeated "yyy1.(parent)=xxx", "yyy2.(parent)=xxx" definitions
	 * in the bundle, especially if all defined views share the same parent.
	 * <p>The parent will typically define the view class and common attributes.
	 * Concrete views might simply consist of an URL definition then:
	 * a la "yyy1.url=/my.jsp", "yyy2.url=/your.jsp".
	 * <p>View definitions that define their own parent or carry their own
	 * class can still override this. Strictly speaking, the rule that a
	 * default parent setting does not apply to a bean definition that
	 * carries a class is there for backwards compatiblity reasons.
	 * It still matches the typical use case.
	 */
	public void setDefaultParentView(String defaultParentView) {
		this.defaultParentView = defaultParentView;
	}

	/**
	 * Specify Locales to initialize eagerly, rather than lazily when actually accessed.
	 * <p>Allows for pre-initialization of common Locales, eagerly checking
	 * the view configuration for those Locales.
	 */
	public void setLocalesToInitialize(Locale[] localesToInitialize) {
		this.localesToInitialize = localesToInitialize;
	}


	protected void initApplicationContext() throws BeansException {
		if (this.localesToInitialize != null) {
			for (int i = 0; i < this.localesToInitialize.length; i++) {
				initFactory(this.localesToInitialize[i]);
			}
		}
	}

	protected View loadView(String viewName, Locale locale) throws Exception {
		BeanFactory factory = initFactory(locale);
		try {
			return (View) factory.getBean(viewName, View.class);
		}
		catch (NoSuchBeanDefinitionException ex) {
			// to allow for ViewResolver chaining
			return null;
		}
	}

	/**
	 * Initialize the View {@link BeanFactory} from the <code>ResourceBundle,
	 * for the given {@link Locale locale}.
	 * <p>Synchronized because of access by parallel threads.
	 * @param locale the target <code>Locale
	 * @return the View factory for the given Locale
	 * @throws BeansException in case of initialization errors
	 */
	protected synchronized BeanFactory initFactory(Locale locale) throws BeansException {
		// Try to find cached factory for Locale:
		// Have we already encountered that Locale before?
		if (isCache()) {
			BeanFactory cachedFactory = (BeanFactory) this.localeCache.get(locale);
			if (cachedFactory != null) {
				return cachedFactory;
			}
		}

		// Build list of ResourceBundle references for Locale.
		List bundles = new LinkedList();
		for (int i = 0; i < this.basenames.length; i++) {
			ResourceBundle bundle = getBundle(this.basenames[i], locale);
			bundles.add(bundle);
		}

		// Try to find cached factory for ResourceBundle list:
		// even if Locale was different, same bundles might have been found.
		if (isCache()) {
			BeanFactory cachedFactory = (BeanFactory) this.bundleCache.get(bundles);
			if (cachedFactory != null) {
				this.localeCache.put(locale, cachedFactory);
				return cachedFactory;
			}
		}

		// Create child ApplicationContext for views.
		GenericWebApplicationContext factory = new GenericWebApplicationContext();
		factory.setParent(getApplicationContext());
		factory.setServletContext(getServletContext());

		// Load bean definitions from resource bundle.
		PropertiesBeanDefinitionReader reader = new PropertiesBeanDefinitionReader(factory);
		reader.setDefaultParentBean(this.defaultParentView);
		for (int i = 0; i < bundles.size(); i++) {
			ResourceBundle bundle = (ResourceBundle) bundles.get(i);
			reader.registerBeanDefinitions(bundle);
		}

		factory.refresh();

		// Cache factory for both Locale and ResourceBundle list.
		if (isCache()) {
			this.localeCache.put(locale, factory);
			this.bundleCache.put(bundles, factory);
		}

		return factory;
	}

	/**
	 * Obtain the resource bundle for the given basename and {@link Locale}.
	 * @param basename the basename to look for
	 * @param locale the <code>Locale to look for
	 * @return the corresponding <code>ResourceBundle
	 * @throws MissingResourceException if no matching bundle could be found
	 * @see java.util.ResourceBundle#getBundle(String, java.util.Locale, ClassLoader)
	 */
	protected ResourceBundle getBundle(String basename, Locale locale) throws MissingResourceException {
		return ResourceBundle.getBundle(basename, locale, getBundleClassLoader());
	}


	/**
	 * Close the bundle View factories on context shutdown.
	 */
	public void destroy() throws BeansException {
		for (Iterator it = this.bundleCache.values().iterator(); it.hasNext();) {
			ConfigurableApplicationContext factory = (ConfigurableApplicationContext) it.next();
			factory.close();
		}
		this.localeCache.clear();
		this.bundleCache.clear();
	}

}