WadlGeneratorConfig.java

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package com.sun.jersey.api.wadl.config;

import java.io.File;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;

import com.sun.jersey.api.core.ResourceConfig;
import com.sun.jersey.server.wadl.WadlGenerator;
import com.sun.jersey.server.wadl.generators.WadlGeneratorApplicationDoc;
import com.sun.jersey.server.wadl.generators.WadlGeneratorGrammarsSupport;
import com.sun.jersey.server.wadl.generators.resourcedoc.WadlGeneratorResourceDocSupport;

/**
 * Provides a configured {@link WadlGenerator} with all decorations (the default
 * wadl generator decorated by other generators).
 * <p>
 * <strong>Creating a WadlGeneratorConfig</strong><br/>
 * <br/>
 * If you want to create an instance at runtime you have two options:
 * <ul>
 * <li>Configure the WadlGenerator class and property names/values</li>
 * <li>Create your {@link WadlGenerator} instances by yourself</li>
 * </ul>
 * 
 * The first option would look like this:
 * <pre><code>WadlGeneratorConfig config = WadlGeneratorConfig
          .generator( MyWadlGenerator.class )
            .prop( "someProperty", "someValue" )
          .generator( MyWadlGenerator2.class )
            .prop( "someProperty", "someValue" )
            .prop( "anotherProperty", "anotherValue" )
          .build();
 * </code></pre>
 * 
 * The second option, creating the {@link WadlGenerator}s by yourself, would look like the following:
 * <pre><code>WadlGeneratorConfig config = WadlGeneratorConfig
            .generator( generator )
            .generator( generator2 )
            .build();
 * </code></pre>
 * <br/>
 * If you want to specify the {@link WadlGeneratorConfig} in the web.xml you have
 * to subclass it and set the servlet init-param {@link ResourceConfig#PROPERTY_WADL_GENERATOR_CONFIG}
 * to the name of your subclass. This class might look like this:
 * <pre><code>class MyWadlGeneratorConfig extends WadlGeneratorConfig {

        public List<WadlGeneratorDescription> configure() {
            return generator( MyWadlGenerator.class )
                .prop( "foo", propValue )
              .generator( MyWadlGenerator2.class )
                .prop( "bar", propValue2 )
              .descriptions();
        }
        
    }
 * </code></pre>
 * 
 * </p>
 * 
 * <p>
 * <strong>Configuring the WadlGenerator</strong><br/>
 * <br/>
 * The {@link WadlGenerator} properties will be populated with the provided properties like this:
 * <ul>
 * <li>The types match exactly:<br/>
 *  if the WadlGenerator property is of type <code>org.example.Foo</code> and the
 *  provided property value is of type <code>org.example.Foo</code></li>
 * <li>Types that provide a constructor for the provided type (mostly java.lang.String)</li>
 * <li>java.io.InputStream: The {@link InputStream} can e.g. represent a file. The stream is loaded from the
 *  property value (provided by the {@link WadlGeneratorDescription}) via 
 *  {@link ClassLoader#getResourceAsStream(String)}. It will be closed after {@link WadlGenerator#init()} was called.
 * </li>
 * 
 * <li><strong>Deprected, will be removed in future versions:</strong><br/>
 * The WadlGenerator property is of type {@link File} and the provided property value is a {@link String}:<br/>
 *  the provided property value can contain the prefix <em>classpath:</em> to denote, that the
 *  path to the file is relative to the classpath. In this case, the property value is stripped by 
 *  the prefix <em>classpath:</em> and the {@link File} is created via
 *  <pre><code>new File( generator.getClass().getResource( strippedFilename ).toURI() )</code></pre>
 *  Notice that the filename is loaded from the classpath in this case, e.g. <em>classpath:test.xml</em>
 *  refers to a file in the package of the class ({@link WadlGeneratorDescription#getGeneratorClass()}). The
 *  file reference <em>classpath:/test.xml</em> refers to a file that is in the root of the classpath.
 * </li>
 * 
 * </ul>
 * </p>
 * <p>
 * <strong>Existing {@link WadlGenerator} implementations:</strong><br/>
 * <br/>
 * <ul>
 *  <li>{@link WadlGeneratorApplicationDoc}</li>
 *  <li>{@link WadlGeneratorGrammarsSupport}</li>
 *  <li>{@link WadlGeneratorResourceDocSupport}</li>
 * </ul>
 * </p>
 * <p>
 * A common example for a {@link WadlGeneratorConfig} would be this:
 * <pre><code>class MyWadlGeneratorConfig extends WadlGeneratorConfig {

        public List<WadlGeneratorDescription> configure() {
            return generator( WadlGeneratorApplicationDoc.class ) 
                .prop( "applicationDocsStream", "application-doc.xml" ) 
              .generator( WadlGeneratorGrammarsSupport.class ) 
                .prop( "grammarsStream", "application-grammars.xml" ) 
              .generator( WadlGeneratorResourceDocSupport.class ) 
                .prop( "resourceDocStream", "resourcedoc.xml" ) 
              .descriptions();
        }
        
    }
 * </code></pre>
 * </p>
 * 
 * @author <a href="mailto:martin.grotzke@freiheit.com">Martin Grotzke</a>
 * @version $Id$
 */
public abstract class WadlGeneratorConfig {

    // private static final Logger LOGGER = Logger.getLogger( WadlGeneratorConfig.class.getName() );

    private WadlGenerator _wadlGenerator;
    
    public WadlGeneratorConfig() {
    }

    /**
     * Creates a new WadlGeneratorConfig from the provided wadlGenerator (must already be initialized).
     * @param wadlGenerator the wadl generator to provide, must not be null.
     */
    public WadlGeneratorConfig( WadlGenerator wadlGenerator ) {
        if ( wadlGenerator == null ) {
            throw new IllegalArgumentException( "The wadl generator must not be null." );
        }
        _wadlGenerator = wadlGenerator;
    }
    
    public abstract List<WadlGeneratorDescription> configure();

    /**
     * Get or load the initialized {@link WadlGenerator}, based on the {@link WadlGeneratorDescription}s
     * provided by {@link #configure()}.
     * @return the initialized {@link WadlGenerator}.
     */
    public synchronized WadlGenerator getWadlGenerator() {
        if ( _wadlGenerator == null ) {
            final List<WadlGeneratorDescription> wadlGeneratorDescriptions = configure();
            try {
                _wadlGenerator = WadlGeneratorLoader.loadWadlGeneratorDescriptions( wadlGeneratorDescriptions );
            } catch ( Exception e ) {
                throw new RuntimeException( "Could not load wadl generators from wadlGeneratorDescriptions.", e );
            }
        }
        return _wadlGenerator;
    }

    /**
     * Start to build an instance of {@link WadlGeneratorConfig}:
     * <pre><code>generator(<class>)
     *      .prop(<name>, <value>)
     *      .prop(<name>, <value>)
     * .generator(<class>)
     *      .prop(<name>, <value>)
     *      .prop(<name>, <value>)
     *      .build()</code></pre>
     * @param generatorClass the class of the wadl generator to configure
     * @return an instance of {@link WadlGeneratorConfigDescriptionBuilder}.
     */
    public static WadlGeneratorConfigDescriptionBuilder generator( Class<? extends WadlGenerator> generatorClass ) {
        return new WadlGeneratorConfigDescriptionBuilder().generator( generatorClass );
    }

    /**
     * Start to build an instance of {@link WadlGeneratorConfig}:
     * <pre><code>generator(<generator>).generator(<generator>).build()</code></pre>
     * @param generator the configured wadl generator
     * @return an instance of {@link WadlGeneratorConfigBuilder}.
     */
    public static WadlGeneratorConfigBuilder generator( WadlGenerator generator ) {
        return new WadlGeneratorConfigBuilder().generator( generator );
    }
    
    public static class WadlGeneratorConfigDescriptionBuilder {
        
        private List<WadlGeneratorDescription> _descriptions;
        private WadlGeneratorDescription _description;

        public WadlGeneratorConfigDescriptionBuilder() {
            _descriptions = new ArrayList<WadlGeneratorDescription>();
        }
        
        public WadlGeneratorConfigDescriptionBuilder generator( Class<? extends WadlGenerator> generatorClass ) {
            if ( _description != null ) {
                _descriptions.add( _description );
            }
            _description = new WadlGeneratorDescription();
            _description.setGeneratorClass( generatorClass );
            return this;
        }
        
        /**
         * Specify the property value for the current {@link WadlGenerator}.
         * <p>
         * The {@link WadlGenerator} property type can be of any type with
         * the following contraints:
         * <p>
         * If the {@link WadlGenerator} property type is equal to the
         * property value type then the property value is set as the
         * {@link WadlGenerator} property value.
         * </p>
         * <p>
         * If the {@link WadlGenerator} property type has a constructor with
         * a single {@link String} parameter type and the property value is a
         * {@link String} then an instance of the property type is constructed
         * with the property value and that instance is set as the
         * {@link WadlGenerator} property value.
         * </p>
         * <p>
         * If the {@link WadlGenerator} property type is of type {@link File},
         * then the specified property value must be a {@link String} starting
         * with the prefix <em>classpath:</em> to denote, that the File shall
         * be loaded from the classpath like this:
         * <pre><code>new File( generator.getClass().getResource( strippedFilename ).toURI() )</code></pre>
         * Notice that the file is loaded as a resource from the classpath
         * in this case, therefore <em>classpath:test.xml</em>
         * refers to a file in the package of the specified 
         * <code><classname></code>. The file reference
         * <em>classpath:/test.xml</em> refers to a file that is in the root
         * of the classpath.
         * </p>
         * <p>
         * If the {@link WadlGenerator} property type is of type
         * {@link InputStream}, then the specified property value must be a
         * {@link String} and the instance of {@link InputStream} is obtained
         * with {@link ClassLoader#getResourceAsStream(String)} using the
         * current threads context classloader.
         * The {@link InputStream} will be closed after
         * {@link WadlGenerator#init()} was called and therefore must not be
         * closed by the {@link WadlGenerator} using this stream.
         * </p>
         * @param propName the property name
         * @param propValue the stringified property value
         * @return this builder instance
         */
        public WadlGeneratorConfigDescriptionBuilder prop( String propName, Object propValue ) {
            if ( _description.getProperties() == null ) {
                _description.setProperties( new Properties() );
            }
            _description.getProperties().put( propName, propValue );
            return this;
        }
        
        public List<WadlGeneratorDescription> descriptions() {
            if ( _description != null ) {
                _descriptions.add( _description );
            }
            return _descriptions;
        }

        public WadlGeneratorConfig build() {
            if ( _description != null ) {
                _descriptions.add( _description );
            }
            return new WadlGeneratorConfigImpl( _descriptions );
        }
        
    }
    
    static class WadlGeneratorConfigImpl extends WadlGeneratorConfig {

        public List<WadlGeneratorDescription> _descriptions;
        
        public WadlGeneratorConfigImpl(
                List<WadlGeneratorDescription> descriptions) {
            _descriptions = descriptions;
        }

        @Override
        public List<WadlGeneratorDescription> configure() {
            return _descriptions;
        }
        
    }
    
    public static class WadlGeneratorConfigBuilder {
        
        private List<WadlGenerator> _generators;

        public WadlGeneratorConfigBuilder() {
            _generators = new ArrayList<WadlGenerator>();
        }
        
        public WadlGeneratorConfigBuilder generator( WadlGenerator generator ) {
            if ( generator == null ) {
                throw new IllegalArgumentException( "The wadl generator must not be null." );
            }
            _generators.add( generator );
            return this;
        }

        public WadlGeneratorConfig build() {
            try {
                final WadlGenerator wadlGenerator = WadlGeneratorLoader.loadWadlGenerators( _generators );
                return new WadlGeneratorConfigGeneratorImpl( wadlGenerator ) {
                    
                };
            } catch ( Exception e ) {
                throw new RuntimeException( "Could not load wadl generators.", e );
            }
        }
        
    }
    
    static class WadlGeneratorConfigGeneratorImpl extends WadlGeneratorConfig {
        
        private final WadlGenerator _wadlGenerator;

        public WadlGeneratorConfigGeneratorImpl(WadlGenerator wadlGenerator) {
            _wadlGenerator = wadlGenerator;
        }

        @Override
        public List<WadlGeneratorDescription> configure() {
            throw new UnsupportedOperationException( "Must not be called" );
        }

        /* (non-Javadoc)
         * @see com.sun.jersey.server.impl.wadl.config.WadlGeneratorConfig#getWadlGenerator()
         */
        @Override
        public synchronized WadlGenerator getWadlGenerator() {
            return _wadlGenerator;
        }
        
    }

}