001    /*
002     * Copyright 2006 Stephen J. McConnell.
003     *
004     * Licensed  under the  Apache License,  Version 2.0  (the "License");
005     * you may not use  this file  except in  compliance with the License.
006     * You may obtain a copy of the License at
007     *
008     *   http://www.apache.org/licenses/LICENSE-2.0
009     *
010     * Unless required by applicable law or agreed to in writing, software
011     * distributed  under the  License is distributed on an "AS IS" BASIS,
012     * WITHOUT  WARRANTIES OR CONDITIONS  OF ANY KIND, either  express  or
013     * implied.
014     *
015     * See the License for the specific language governing permissions and
016     * limitations under the License.
017     */
018    
019    package net.dpml.util;
020    
021    import java.net.URI;
022    import java.net.URISyntaxException;
023    
024    /**
025     * Build-time value resolver.
026     */
027    public class SimpleResolver implements Resolver
028    {
029       /**
030        * Utility function supporting resolution of uris containing 'resource' or 
031        * 'alias' schemes.  If the supplied uri scheme is 'resource' or 'alias' the 
032        * reference is resolved to a artifact type, group and name from which a 
033        * resource is resolved and the uri returned.  If the scheme is resource
034        * the usi of the resource is returned. If the scheme is 'alias' a 
035        * link alias is returned.  If the scheme is not 'resource' or 'alias' 
036        * the argument will be evaluated as a normal transit artifact uri 
037        * specification.
038        * 
039        * @param ref the uri argument
040        * @return the uri value
041        * @exception URISyntaxException if an error occurs during uri creation
042        */
043        public URI toURI( String ref ) throws URISyntaxException
044        {
045            String value = resolve( ref );
046            return new URI( value );
047        }
048        
049       /**
050        * Return a property value.
051        * @param key the property key
052        * @return the property value
053        */
054        public String getProperty( String key )
055        {
056            return System.getProperty( key );
057        }
058        
059       /**
060        * Return a property value.
061        * @param key the property key
062        * @param value the default value
063        * @return the property value
064        */
065        public String getProperty( String key, String value )
066        {
067            return System.getProperty( key, value );
068        }
069        
070       /**
071        * Symbolic expansion of a supplied value.
072        * Replace any occurances of ${[key]} with the value of the property
073        * assigned to the [key] in system properties.
074        * @param value a string containing possibly multiple ${[value]} sequences
075        * @return the expanded string
076        */
077        public String resolve( String value )
078        {
079            return PropertyResolver.resolve( value );
080        }
081    }