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// *                                                                                                                         *
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011// * specific language governing permissions and limitations under the License.                                              *
012// ***************************************************************************************************************************
013package org.apache.juneau.rest.vars;
014
015import org.apache.juneau.*;
016import org.apache.juneau.rest.*;
017import org.apache.juneau.rest.annotation.*;
018import org.apache.juneau.svl.*;
019
020/**
021 * URL variable resolver.
022 * 
023 * <p>
024 * The format for this var is <js>"$U{uri}"</js>.
025 * 
026 * <p>
027 * The advantage of using this variable is that you can resolve URLs with special protocols such as
028 * <js>"servlet:/xxx"</js>.
029 * 
030 * <p>
031 * See {@link UriResolver} for the kinds of URIs that can be resolved.
032 * <ul>
033 *    <li>{@link HtmlDoc#widgets() @HtmlDoc.widgets()}
034 * </ul>
035 * 
036 * <p>
037 * Uses the URI resolver returned by {@link RestRequest#getUriResolver(UriResolution, UriRelativity)} with resolution
038 * {@link UriResolution#ROOT_RELATIVE} and relativity {@link UriRelativity#RESOURCE}.
039 * 
040 * <h5 class='section'>See Also:</h5>
041 * <ul>
042 *    <li class='link'><a class="doclink" href="../../../../../overview-summary.html#juneau-rest-server.SvlVariables">Overview &gt; juneau-rest-server &gt; SVL Variables</a>
043 * </ul>
044 */
045public class UrlVar extends SimpleVar {
046
047   private static final String SESSION_req = "req";
048
049   /** The name of this variable. */
050   public static final String NAME = "U";
051
052   /**
053    * Constructor.
054    */
055   public UrlVar() {
056      super(NAME);
057   }
058
059   @Override /* Parameter */
060   public String resolve(VarResolverSession session, String key) {
061      RestRequest req = session.getSessionObject(RestRequest.class, SESSION_req);
062      return req.getUriResolver().resolve(key);
063   }
064}