001// ***************************************************************************************************************************
002// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
003// * distributed with this work for additional information regarding copyright ownership.  The ASF licenses this file        *
004// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
005// * with the License.  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 distributed under the License is distributed on an  *
010// * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the License for the        *
011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.rest;
014
015import org.apache.juneau.internal.*;
016
017/**
018 * Denotes the default resolver for child resources.
019 * 
020 * The default implementation simply instantiates the class using one of the following constructors:
021 * <ul>
022 *    <li><code><jk>public</jk> T(RestContextBuilder)</code>
023 *    <li><code><jk>public</jk> T()</code>
024 * </ul>
025 * 
026 * <p>
027 * The former constructor can be used to get access to the {@link RestContextBuilder} object to get access to the
028 * config file and initialization information or make programmatic modifications to the resource before
029 * full initialization.
030 * 
031 * <p>
032 * Child classes can also be defined as inner-classes of the parent resource class.
033 * 
034 * <h5 class='section'>See Also:</h5>
035 * <ul>
036 *    <li class='link'><a class="doclink" href="../../../../overview-summary.html#juneau-rest-server.ResourceResolvers">Overview &gt; juneau-rest-server &gt; Resource Resolvers</a>
037 * </ul>
038 */
039public class BasicRestResourceResolver implements RestResourceResolver {
040
041   @Override /* RestResourceResolver */
042   public Object resolve(Object parent, Class<?> c, RestContextBuilder builder) throws Exception {
043      try {
044         Object r = ClassUtils.newInstanceFromOuter(parent, Object.class, c, true, builder);
045         if (r != null)
046            return r;
047      } catch (Exception e) {
048         throw new RestServletException("Could not instantiate resource class ''{0}''", c.getName()).initCause(e);
049      }
050      throw new RestServletException("Could not find public constructor for class ''{0}''.", c);
051   }
052}