001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.juneau.rest.matcher;
018
019import org.apache.juneau.rest.annotation.*;
020
021import jakarta.servlet.http.*;
022
023/**
024 * Class used for defining method-level matchers using the {@link RestOp#matchers() @RestOp(matchers)} annotation.
025 *
026 * <p>
027 * Matchers are used to allow multiple Java methods to handle requests assigned to the same URL path pattern, but
028 * differing based on some request attribute, such as a specific header value.
029 * For example, matchers can be used to provide two different methods for handling requests from two different client
030 * versions.
031 *
032 * <p>
033 * Java methods with matchers associated with them are always attempted before Java methods without matchers.
034 * This allows a 'default' method to be defined to handle requests where no matchers match.
035 *
036 * <p>
037 * When multiple matchers are specified on a method, only one matcher is required to match.
038 * This is opposite from the {@link RestOp#guards() @RestOp(guards)} annotation, where all guards are required to match in order to
039 * execute the method.
040 *
041 * <h5 class='section'>Example:</h5>
042 * <p class='bjava'>
043 *    <jk>public class</jk> MyResource <jk>extends</jk> BasicRestServlet {
044 *
045 *       <ja>@RestGet</ja>(path=<js>"/foo"</js>, matchers=IsDNT.<jk>class</jk>)
046 *       <jk>public</jk> Object doGetWithDNT() {
047 *          <jc>// Handle request with Do-Not-Track specified</jc>
048 *       }
049 *
050 *       <ja>@RestGet</ja>(<js>"/foo"</js>)
051 *       <jk>public</jk> Object doGetWithoutDNT() {
052 *          <jc>// Handle request without Do-Not-Track specified</jc>
053 *       }
054 *    }
055 *
056 *    <jk>public class</jk> IsDNT <jk>extends</jk> RestMatcher {
057 *       <ja>@Override</ja>
058 *       <jk>public boolean</jk> matches(HttpServletRequest <jv>req</jv>) {
059 *          <jk>return</jk> <js>"1"</js>.equals(<jv>req</jv>.getHeader(<js>"DNT"</js>));
060 *       }
061 *    }
062 * </p>
063 *
064 * <p>
065 * Instances must provide one of the following public constructors:
066 * <ul>
067 *    <li>No-args.
068 *    <li>The following args: <c>Object resource, Method javaMethod</c>.
069 *       <br>This gives access to the servlet/resource and Java method it's applied to.
070 * </ul>
071 *
072 * <h5 class='section'>See Also:</h5><ul>
073 *    <li class='link'><a class="doclink" href="https://juneau.apache.org/docs/topics/RestOpAnnotatedMethodBasics">@RestOp-Annotated Method Basics</a>
074 * </ul>
075 */
076public abstract class RestMatcher {
077
078   /**
079    * Returns <jk>true</jk> if the specified request matches this matcher.
080    *
081    * @param req The servlet request.
082    * @return <jk>true</jk> if the specified request matches this matcher.
083    */
084   public abstract boolean matches(HttpServletRequest req);
085
086   /**
087    * Returns <jk>true</jk> if this matcher is required to match in order for the method to be invoked.
088    *
089    * <p>
090    * If <jk>false</jk>, then only one of the matchers must match.
091    *
092    * @return <jk>true</jk> if this matcher is required to match in order for the method to be invoked.
093    */
094   public boolean required() {
095      return false;
096   }
097}