AbstractResource.java

/*
 * JBoss, Home of Professional Open Source
 * Copyright 2008, Red Hat Middleware LLC, and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jboss.seam.resteasy;

import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;

import javax.ws.rs.core.Context;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.MediaType;

/**
 * Resource class used by ResourceHome and ResourceQuery components. Contains
 * information about path, media types and entity class the component operates
 * on.
 *
 * @author Jozef Hartinger
 * @param <T> entity class
 */
public abstract class AbstractResource<T>
{

   @Context
   private HttpHeaders httpHeaders;

   private String path = null;
   private MediaType[] mediaTypes = null;
   private Class entityClass = null;

   public AbstractResource()
   {
      mediaTypes = new MediaType[]{MediaType.APPLICATION_XML_TYPE};
   }

   public String[] getMediaTypes()
   {
      String[] mediaTypes = new String[this.mediaTypes.length];
      for (int i = 0; i < mediaTypes.length; i++)
      {
         mediaTypes[i] = this.mediaTypes[i].toString();
      }
      return mediaTypes;
   }

   public void setMediaTypes(String[] mediaTypes)
   {
      this.mediaTypes = new MediaType[mediaTypes.length];
      for (int i = 0; i < mediaTypes.length; i++)
      {
         this.mediaTypes[i] = MediaType.valueOf(mediaTypes[i]);
      }
   }

   public void setEntityClass(Class entityClass)
   {
      this.entityClass = entityClass;
   }

   /**
    * Retrieve entity class. If not set, type parameters of a superclass are
    * examined.
    *
    * @return entity class
    */
   public Class<T> getEntityClass()
   {
      if (entityClass == null)
      {
         Type superclass = this.getClass().getGenericSuperclass();
         if (superclass instanceof ParameterizedType)
         {
            ParameterizedType parameterizedSuperclass = (ParameterizedType) superclass;
            if (parameterizedSuperclass.getActualTypeArguments().length > 0)
            {
               return (Class) parameterizedSuperclass.getActualTypeArguments()[0];
            }
         }
         throw new RuntimeException("Unable to determine entity class.");
      }
      else
      {
         return entityClass;
      }
   }

   /**
    * Retrieve a suffix of this resource's URI. See {@link #setPath(String path)}
    *
    * @return path
    * @see javax.ws.rs.Path
    */
   public String getPath()
   {
      return path;
   }

   /**
    * Set the path this resource will operate on. This method is intended to be
    * used only by Seam to create a resource configured in component descriptor.
    * To specify the path in other cases, use @Path annotation. See
    *
    * @param path
    */
   public void setPath(String path)
   {
      this.path = path;
   }

   /**
    * Select a media type that will be used for marshalling entity. Media type
    * is selected from the intersection of media types supported by this
    * resource and media types accepted by client.
    *
    * @return selected media type, returns null if no suitable media type is
    *         found
    */
   protected MediaType selectResponseMediaType()
   {
      for (MediaType acceptedMediaType : httpHeaders.getAcceptableMediaTypes())
      {
         for (MediaType availableMediaType : mediaTypes)
         {
            if (acceptedMediaType.isCompatible(availableMediaType))
               return availableMediaType;
         }
      }
      return null;
   }

   /**
    * Check if media type passed as parameter is supported by this resource.
    *
    * @param mediaType
    * @return true if and only if the media type is accepted by this resource
    */
   public boolean isMediaTypeCompatible(MediaType mediaType)
   {
      for (MediaType availableMediaType : mediaTypes)
      {
         if (availableMediaType.isCompatible(mediaType))
         {
            return true;
         }
      }
      return false;
   }
}