SpringFinder.java

/**
 * Copyright 2005-2014 Restlet
 * 
 * The contents of this file are subject to the terms of one of the following
 * open source licenses: Apache 2.0 or or EPL 1.0 (the "Licenses"). You can
 * select the license that you prefer but you may not use this file except in
 * compliance with one of these Licenses.
 * 
 * You can obtain a copy of the Apache 2.0 license at
 * http://www.opensource.org/licenses/apache-2.0
 * 
 * You can obtain a copy of the EPL 1.0 license at
 * http://www.opensource.org/licenses/eclipse-1.0
 * 
 * See the Licenses for the specific language governing permissions and
 * limitations under the Licenses.
 * 
 * Alternatively, you can obtain a royalty free commercial license with less
 * limitations, transferable or non-transferable, directly at
 * http://restlet.com/products/restlet-framework
 * 
 * Restlet is a registered trademark of Restlet S.A.S.
 */

package org.restlet.ext.spring;

import java.util.logging.Level;

import org.restlet.Context;
import org.restlet.Request;
import org.restlet.Response;
import org.restlet.Restlet;
import org.restlet.resource.Finder;
import org.restlet.resource.ServerResource;

/**
 * Finder that is specialized for easier usage by Spring wiring services. The
 * idea is to create a singleton Spring bean based on that SpringFinder and
 * configure it using Spring's "lookup-method" element to return instances of a
 * "prototype" bean for {@link #create()}. Finally, attach the SpringFinder to
 * your Router. When the {@link #create()} method is invoked, a new instance of
 * your prototype bean will be created and returned. A sample XML for
 * "lookup-method":
 * 
 * <pre>
 *      <bean id="myFinder" class="org.restlet.ext.spring.SpringFinder"> 
 *              <lookup-method name="create" bean="myResource"/> 
 *      </bean>
 *       
 *      <bean id="myResource" class="com.mycompany.rest.resource.MyResource" scope="prototype"> 
 *              <property name="aProperty" value="anotherOne"/> 
 *              <property name="oneMore" value="true"/>
 *      </bean>
 * </pre>
 * 
 * Note that the <a href="http://cglib.sourceforge.net/">Code Generation
 * Library</a> (cglib) will be required in order to use the Spring's lookup
 * method mechanism.<br>
 * <br>
 * Concurrency note: instances of this class or its subclasses can be invoked by
 * several threads at the same time and therefore must be thread-safe. You
 * should be especially careful when storing state in member variables.
 * 
 * @see <a href="http://www.springframework.org/">Spring home page</a>
 * @author Jerome Louvel
 */
public class SpringFinder extends Finder {

    /**
     * Constructor.
     */
    public SpringFinder() {
        super();
    }

    /**
     * Constructor.
     * 
     * @param context
     *            The parent context.
     */
    public SpringFinder(Context context) {
        super(context);
    }

    /**
     * Constructor.
     * 
     * @param context
     *            The context.
     * @param targetClass
     *            The target resource class.
     */
    public SpringFinder(Context context,
            Class<? extends ServerResource> targetClass) {
        super(context, targetClass);
    }

    /**
     * Constructor.
     * 
     * @param restlet
     *            The parent Restlet.
     */
    public SpringFinder(Restlet restlet) {
        super(restlet.getContext());
    }

    /**
     * Creates a new instance of the {@link ServerResource} class designated by
     * the "targetClass" property. This method is intended to be configured as a
     * lookup method in Spring.
     * 
     * @return The created resource or null.
     */
    public ServerResource create() {
        ServerResource result = null;

        if (getTargetClass() != null) {
            try {
                // Invoke the default constructor
                result = (ServerResource) getTargetClass().newInstance();
            } catch (Exception e) {
                getLogger()
                        .log(Level.WARNING,
                                "Exception while instantiating the target server resource.",
                                e);
            }
        }

        return result;
    }

    /**
     * Calls the {@link #create()} method that can be configured as a lookup
     * method in Spring. Overriding this method was necessary for direct calls
     * to it, for example by unit tests.
     */
    @Override
    public ServerResource create(Class<? extends ServerResource> targetClass,
            Request request, Response response) {
        return create(request, response);
    }

    @Override
    public org.restlet.resource.ServerResource create(Request request,
            Response response) {
        return create();
    }

}