Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.wicket.request; /** * Maps {@link IRequestHandler}(s) into {@link Url}(s) and {@link Request}(s) to * {@link IRequestHandler}(s). For {@link IRequestHandler}s and {@link Request}s the implementation * doesn't recognize, the {@link #mapHandler(IRequestHandler)} and {@link #mapRequest(Request)} * methods must return {@code null}. * * The workflow is: the Application class collects a set of {@link IRequestMapper}s and for each * request the {@link IRequestCycle request cycle} asks these mappers whether any of them knows how * to handle the current {@link Request}s {@link Url url}. Wicket pre-configures several mappers * which are used for the basic application functionality like a mapper for the home page, a mapper * for Wicket resources, for bookmarkable pages, etc. The user application can add additional * mappers with the various WebApplication#mountXYZ() methods. * * The mapper has two main tasks: * * <ol> * <li>To create {@link IRequestHandler} that will produce the response. When a request comes Wicket * uses {@link #getCompatibilityScore(Request)} to decide which mapper should be asked first to * process the request. If two mappers have the same score then the one added later is asked first. * This way users mappers have precedence than the system ones. If a mapper knows how to handle the * requests url then it should return non-{@code null} {@link IRequestHandler}.</li> * <li> * The second task is to produce {@link Url} for an {@link IRequestHandler}. This is needed at * markup rendering time to create the urls for links, forms' action attribute, etc.</li> * </ol> * * @author Matej Knopp */ public interface IRequestMapper { /** * Returns {@link IRequestHandler} for the request or <code>null</code> if the {@link Url} is * not recognized. * * @param request * provides access to request data (i.e. Url and Parameters) * * @return RequestHandler instance or <code>null</code> */ IRequestHandler mapRequest(Request request); /** * Returns the score representing how compatible this request mapper is to processing the given * request. When a request comes in all mappers are scored and are tried in order from highest * score to lowest. * <p> * A good criteria for calculating the score is the number of matched url segments. For example * when there are two mappers for a mounted page, one mapped to <code>/foo</code> another to * <code>/foo/bar</code> and the incoming request URL is </code>/foo/bar/baz</code>, the mapping * to <code>/foo/bar</code> should probably handle the request first as it has matching segments * count of 2 while the first one has only matching segments count of 1. * <p> * Note that the method can return value greater then zero even if the mapper does not recognize * the request. * * @param request * @return the compatibility score, e.g. count of matching segments */ int getCompatibilityScore(Request request); /** * Returns the {@link Url} for given {@link IRequestHandler} or <code>null</code> if the request * handler is not recognized. * * @param requestHandler * @return Url instance or <code>null</code>. */ Url mapHandler(IRequestHandler requestHandler); }