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012// ***************************************************************************************************************************
013package org.apache.juneau.rest.matcher;
014
015import jakarta.servlet.http.*;
016
017import org.apache.juneau.rest.annotation.*;
018
019/**
020 * Class used for defining method-level matchers using the {@link RestOp#matchers() @RestOp(matchers)} annotation.
021 *
022 * <p>
023 * Matchers are used to allow multiple Java methods to handle requests assigned to the same URL path pattern, but
024 * differing based on some request attribute, such as a specific header value.
025 * For example, matchers can be used to provide two different methods for handling requests from two different client
026 * versions.
027 *
028 * <p>
029 * Java methods with matchers associated with them are always attempted before Java methods without matchers.
030 * This allows a 'default' method to be defined to handle requests where no matchers match.
031 *
032 * <p>
033 * When multiple matchers are specified on a method, only one matcher is required to match.
034 * This is opposite from the {@link RestOp#guards() @RestOp(guards)} annotation, where all guards are required to match in order to
035 * execute the method.
036 *
037 * <h5 class='section'>Example:</h5>
038 * <p class='bjava'>
039 *    <jk>public class</jk> MyResource <jk>extends</jk> BasicRestServlet {
040 *
041 *       <ja>@RestGet</ja>(path=<js>"/foo"</js>, matchers=IsDNT.<jk>class</jk>)
042 *       <jk>public</jk> Object doGetWithDNT() {
043 *          <jc>// Handle request with Do-Not-Track specified</jc>
044 *       }
045 *
046 *       <ja>@RestGet</ja>(<js>"/foo"</js>)
047 *       <jk>public</jk> Object doGetWithoutDNT() {
048 *          <jc>// Handle request without Do-Not-Track specified</jc>
049 *       }
050 *    }
051 *
052 *    <jk>public class</jk> IsDNT <jk>extends</jk> RestMatcher {
053 *       <ja>@Override</ja>
054 *       <jk>public boolean</jk> matches(HttpServletRequest <jv>req</jv>) {
055 *          <jk>return</jk> <js>"1"</js>.equals(<jv>req</jv>.getHeader(<js>"DNT"</js>));
056 *       }
057 *    }
058 * </p>
059 *
060 * <p>
061 * Instances must provide one of the following public constructors:
062 * <ul>
063 *    <li>No-args.
064 *    <li>The following args: <c>Object resource, Method javaMethod</c>.
065 *       <br>This gives access to the servlet/resource and Java method it's applied to.
066 * </ul>
067 *
068 * <h5 class='section'>See Also:</h5><ul>
069 *    <li class='link'><a class="doclink" href="../../../../../index.html#jrs.RestOpAnnotatedMethods">@RestOp-Annotated Methods</a>
070 * </ul>
071 */
072public abstract class RestMatcher {
073
074   /**
075    * Returns <jk>true</jk> if the specified request matches this matcher.
076    *
077    * @param req The servlet request.
078    * @return <jk>true</jk> if the specified request matches this matcher.
079    */
080   public abstract boolean matches(HttpServletRequest req);
081
082   /**
083    * Returns <jk>true</jk> if this matcher is required to match in order for the method to be invoked.
084    *
085    * <p>
086    * If <jk>false</jk>, then only one of the matchers must match.
087    *
088    * @return <jk>true</jk> if this matcher is required to match in order for the method to be invoked.
089    */
090   public boolean required() {
091      return false;
092   }
093}