001    // Copyright 2004, 2005 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.hivemind;
016    
017    import java.net.URL;
018    import java.util.Locale;
019    
020    /**
021     * Describes the location of a resource, such as a module deployment
022     * descriptor, or a messages file.
023     * 
024     * <p>
025     * Resources may be either base or localized.  A localized
026     * version of a base resource may be obtained
027     * via {@link #getLocalization(Locale)}.
028     * 
029     * <p>
030     * Resource locations are used as Map keys, they must 
031     * implement {@link java.lang.Object#hashCode()} and
032     * {@link java.lang.Object#equals(java.lang.Object)}
033     * properly.
034     * 
035     * <p>
036     * Resource locations are valid even if the corresponding
037     * resource <i>doesn't exist</i>.  To verify if a localization
038     * actually exists, use {@link #getResourceURL()}, which returns
039     * null if the resource doesn't exist.  {@link #getLocalization(Locale)}
040     * returns only real resource locations, where the resource exists.
041     * 
042     * <p>
043     * Folders must be represented with a trailing slash.
044     *
045     * @author Howard Lewis Ship
046     *
047     **/
048    
049    public interface Resource
050    {
051        /**
052         * Returns a URL for the resource.
053         * 
054         * @return the URL for the resource if it exists, or null if it does not
055         * 
056         */
057        
058        public URL getResourceURL();
059        
060        /**
061         * Returns the file name portion of the resource location.
062         * 
063         */
064        
065        public String getName();
066        
067        /**
068         * Returns a localized version of this resource (or this resource, if no
069         * appropriate localization is found).  Should only be invoked
070         * on a base resource.
071         * 
072         * @param locale to localize for, or null for no localization.
073         * @return a localized version of this resource, of null if the resource
074         * itself does not exist.
075         * 
076         */
077        
078        public Resource getLocalization(Locale locale);
079        
080        /**
081         * Returns at a relative location to this resource.  
082         * The new resource may or may not exist; this can be determined
083         * via {@link #getResourceURL()}.
084         * 
085         * @param name name of new resource, possibly as a relative path, or
086         * as an absolute path (starting with a slash).
087         * 
088         */
089        
090        public Resource getRelativeResource(String name);
091        
092        /**
093         * Returns the path that represents the resource.  This should 
094         * only be used when the type of resource is known.
095         * 
096         */
097        
098        public String getPath();
099    
100        /**
101         * Returns the locale for which this resource has been localized 
102         * or null if the resource has not been localized. This should 
103         * only be used when the type of resource is known.
104         *
105         * This locale is the same or more general than the locale for which localization 
106         * was requested. For example, if the requested locale was en_US, but only the file 
107         * Home_en was found, this locale returned would be en. 
108         */
109        
110        public Locale getLocale();
111    }