org.apache.wicket.SharedResources.java Source code

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.wicket;

import java.util.Locale;

import org.apache.wicket.request.resource.IResource;
import org.apache.wicket.request.resource.ResourceReference;
import org.apache.wicket.request.resource.ResourceReference.Key;
import org.apache.wicket.request.resource.ResourceReferenceRegistry;
import org.apache.wicket.util.lang.Args;

/**
 * Class which holds shared resources. Resources can be shared by name. An optional scope can be
 * given to prevent naming conflicts and a locale and/or style can be given as well.
 * 
 * <p>
 * Unlike component hosted resources, shared resources have stable URLs, which makes them suitable
 * for indexing by web crawlers and caching by web browsers. As they are also not synchronised on
 * the {@link Session}, they can be loaded asynchronously, which is important with images and
 * resources such as JavaScript and CSS.
 */
public class SharedResources {
    private final ResourceReferenceRegistry registry;

    /**
     * Construct.
     * 
     * @param registry
     */
    public SharedResources(ResourceReferenceRegistry registry) {
        this.registry = Args.notNull(registry, "registry");
    }

    /**
     * A {@link ResourceReference} that is used to register a reference to a known {@link IResource}
     */
    private static final class AutoResourceReference extends ResourceReference {
        private static final long serialVersionUID = 1L;

        private final IResource resource;

        private AutoResourceReference(Class<?> scope, String name, Locale locale, String style, String variation,
                IResource resource) {
            super(scope, name, locale, style, variation);
            this.resource = resource;
        }

        @Override
        public IResource getResource() {
            return resource;
        }
    }

    /**
     * Adds a resource.
     * 
     * @param scope
     *            Scope of resource
     * @param name
     *            Logical name of resource
     * @param locale
     *            The locale of the resource
     * @param style
     *            The resource style (see {@link org.apache.wicket.Session})
     * @param variation
     *            The component specific variation of the style
     * @param resource
     *            Resource to store
     */
    public final void add(final Class<?> scope, final String name, final Locale locale, final String style,
            final String variation, final IResource resource) {
        ResourceReference ref = new AutoResourceReference(scope, name, locale, style, variation, resource);
        registry.registerResourceReference(ref);
    }

    /**
     * Adds a resource.
     * 
     * @param name
     *            Logical name of resource
     * @param locale
     *            The locale of the resource
     * @param resource
     *            Resource to store
     */
    public final void add(final String name, final Locale locale, final IResource resource) {
        add(Application.class, name, locale, null, null, resource);
    }

    /**
     * Adds a resource.
     * 
     * @param name
     *            Logical name of resource
     * @param resource
     *            Resource to store
     */
    public final void add(final String name, final IResource resource) {
        add(Application.class, name, null, null, null, resource);
    }

    /**
     * Resolves a {@link ResourceReference} for a shared resource by using
     * {@link org.apache.wicket.Application} as a scope and {@code null} for
     * locale, style and variation.
     *
     * @param name
     *            Logical name of resource
     */
    public final ResourceReference get(String name) {
        return get(Application.class, name, null, null, null, false);
    }

    /**
     * Resolves a {@link ResourceReference} for a shared resource.
     * 
     * @param scope
     *            Scope of resource
     * @param name
     *            Logical name of resource
     * @param locale
     *            The locale of the resource
     * @param style
     *            The resource style (see {@link org.apache.wicket.Session})
     * @param variation
     *            The component specific variation of the style
     * @param strict
     *            If true, "weaker" combination of scope, name, locale etc. are not tested
     * @return Either the resource reference found in the registry or, if requested, a resource
     *         reference automatically created based on the parameters provided. The automatically
     *         created resource reference will automatically be added to the registry.
     */
    public ResourceReference get(Class<?> scope, String name, Locale locale, String style, String variation,
            boolean strict) {
        return registry.getResourceReference(scope, name, locale, style, variation, strict, true);
    }

    /**
     * Removes a resource.
     * 
     * @param key
     *            the resource reference's identifier
     * @return the removed {@link ResourceReference}. {@code null} if there was no registration for
     *         this {@link Key}
     */
    public final ResourceReference remove(final Key key) {
        return registry.unregisterResourceReference(key);
    }
}