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.core.request.mapper; import java.util.List; import javax.servlet.http.HttpServletResponse; import org.apache.wicket.Application; import org.apache.wicket.request.IRequestHandler; import org.apache.wicket.request.IRequestMapper; import org.apache.wicket.request.Request; import org.apache.wicket.request.Url; import org.apache.wicket.request.handler.resource.ResourceReferenceRequestHandler; import org.apache.wicket.request.http.flow.AbortWithHttpErrorCodeException; import org.apache.wicket.request.mapper.parameter.INamedParameters; import org.apache.wicket.request.mapper.parameter.IPageParametersEncoder; import org.apache.wicket.request.mapper.parameter.PageParameters; import org.apache.wicket.request.mapper.parameter.PageParametersEncoder; import org.apache.wicket.request.resource.IResource; import org.apache.wicket.request.resource.ResourceReference; import org.apache.wicket.request.resource.caching.IResourceCachingStrategy; import org.apache.wicket.request.resource.caching.IStaticCacheableResource; import org.apache.wicket.request.resource.caching.ResourceUrl; import org.apache.wicket.resource.ResourceUtil; import org.apache.wicket.util.lang.Args; import org.apache.wicket.util.string.Strings; /** * A {@link IRequestMapper} to mount resources to a custom mount path * <ul> * <li>maps indexed parameters to path segments</li> * <li>maps named parameters to query string arguments or placeholder path segments</li> * </ul> * * <strong>sample structure of url</strong> * * <pre> * /myresources/${category}/images/[indexed-param-0]/[indexed-param-1]?[named-param-1=value]&[named-param-2=value2] * </pre> * * <h4>sample usage</h4> * * in your wicket application's init() method use a statement like this * <p/> * * <pre> * mountResource("/images", new ImagesResourceReference())); * </pre> * * Note: Mounted this way the resource reference has application scope, i.e. it is shared between * all users of the application. It is recommended to not keep any state in it. * * @see org.apache.wicket.protocol.http.WebApplication#mountResource(String, * org.apache.wicket.request.resource.ResourceReference) * * @author Peter Ertl */ public class ResourceMapper extends AbstractBookmarkableMapper { // encode page parameters into url + decode page parameters from url private final IPageParametersEncoder parametersEncoder; // mount path (= segments) the resource is bound to private final String[] mountSegments; // resource that the mapper links to private final ResourceReference resourceReference; /** * create a resource mapper for a resource * * @param path * mount path for the resource * @param resourceReference * resource reference that should be linked to the mount path * * @see #ResourceMapper(String, org.apache.wicket.request.resource.ResourceReference, * org.apache.wicket.request.mapper.parameter.IPageParametersEncoder) */ public ResourceMapper(String path, ResourceReference resourceReference) { this(path, resourceReference, new PageParametersEncoder()); } /** * create a resource mapper for a resource * * @param path * mount path for the resource * @param resourceReference * resource reference that should be linked to the mount path * @param encoder * encoder for url parameters */ public ResourceMapper(String path, ResourceReference resourceReference, IPageParametersEncoder encoder) { super(path, encoder); Args.notNull(resourceReference, "resourceReference"); this.resourceReference = resourceReference; mountSegments = getMountSegments(path); parametersEncoder = encoder; } @Override public IRequestHandler mapRequest(final Request request) { final Url url = new Url(request.getUrl()); // now extract the page parameters from the request url PageParameters parameters = extractPageParameters(request, mountSegments.length, parametersEncoder); if (parameters != null) { parameters.setLocale(resolveLocale()); } // remove caching information from current request removeCachingDecoration(url, parameters); // check if url matches mount path if (urlStartsWith(url, mountSegments) == false) { return null; } // check if there are placeholders in mount segments for (int index = 0; index < mountSegments.length; ++index) { String placeholder = getPlaceholder(mountSegments[index]); if (placeholder != null) { // extract the parameter from URL if (parameters == null) { parameters = newPageParameters(); } parameters.add(placeholder, url.getSegments().get(index), INamedParameters.Type.PATH); } } return new ResourceReferenceRequestHandler(resourceReference, parameters); } @Override protected final UrlInfo parseRequest(final Request request) { throw new UnsupportedOperationException(); } @Override protected final Url buildUrl(final UrlInfo info) { throw new UnsupportedOperationException(); } @Override protected final boolean pageMustHaveBeenCreatedBookmarkable() { throw new UnsupportedOperationException(); } @Override public int getCompatibilityScore(Request request) { Url originalUrl = new Url(request.getUrl()); PageParameters parameters = extractPageParameters(request, mountSegments.length, parametersEncoder); if (parameters != null) { parameters.setLocale(resolveLocale()); } removeCachingDecoration(originalUrl, parameters); Request requestWithoutDecoration = request.cloneWithUrl(originalUrl); int score = super.getCompatibilityScore(requestWithoutDecoration); if (score > 0) { score--; // pages always have priority over resources } else { score = -1; } return score; } @Override public Url mapHandler(IRequestHandler requestHandler) { if ((requestHandler instanceof ResourceReferenceRequestHandler) == false) { return null; } ResourceReferenceRequestHandler handler = (ResourceReferenceRequestHandler) requestHandler; // see if request handler addresses the resource reference we serve if (resourceReference.equals(handler.getResourceReference()) == false) { return null; } Url url = new Url(); // add mount path segments for (String segment : mountSegments) { url.getSegments().add(segment); } // replace placeholder parameters PageParameters parameters = newPageParameters(); parameters.mergeWith(handler.getPageParameters()); for (int index = 0; index < mountSegments.length; ++index) { String placeholder = getPlaceholder(mountSegments[index]); if (placeholder != null) { url.getSegments().set(index, parameters.get(placeholder).toString("")); parameters.remove(placeholder); } } // add caching information addCachingDecoration(url, parameters); ResourceUtil.encodeResourceReferenceAttributes(url, resourceReference); // create url return encodePageParameters(url, parameters, parametersEncoder); } protected IResourceCachingStrategy getCachingStrategy() { return Application.get().getResourceSettings().getCachingStrategy(); } protected void addCachingDecoration(Url url, PageParameters parameters) { final List<String> segments = url.getSegments(); final int lastSegmentAt = segments.size() - 1; final String filename = segments.get(lastSegmentAt); if (Strings.isEmpty(filename) == false) { final IResource resource = resourceReference.getResource(); if (resource instanceof IStaticCacheableResource) { final IStaticCacheableResource cacheable = (IStaticCacheableResource) resource; if (cacheable.isCachingEnabled()) { final ResourceUrl cacheUrl = new ResourceUrl(filename, parameters); getCachingStrategy().decorateUrl(cacheUrl, cacheable); if (Strings.isEmpty(cacheUrl.getFileName())) { if (Application.exists() && Application.get().usesDeploymentConfig()) { throw new AbortWithHttpErrorCodeException(HttpServletResponse.SC_NOT_FOUND, "caching strategy returned empty name for " + resource); } else { throw new IllegalStateException("caching strategy returned empty name for " + resource); } } segments.set(lastSegmentAt, cacheUrl.getFileName()); } } } } protected void removeCachingDecoration(Url url, PageParameters parameters) { final List<String> segments = url.getSegments(); if (segments.isEmpty() == false) { // get filename (the last segment) final int lastSegmentAt = segments.size() - 1; String filename = segments.get(lastSegmentAt); // ignore requests with empty filename if (Strings.isEmpty(filename)) { return; } // create resource url from filename and query parameters final ResourceUrl resourceUrl = new ResourceUrl(filename, parameters); // remove caching information from request getCachingStrategy().undecorateUrl(resourceUrl); // check for broken caching strategy (this must never happen) if (Strings.isEmpty(resourceUrl.getFileName())) { throw new IllegalStateException("caching strategy returned empty name for " + resourceUrl); } segments.set(lastSegmentAt, resourceUrl.getFileName()); } } }