Java tutorial
/* * #%L * ACS AEM Commons Bundle * %% * Copyright (C) 2013 Adobe * %% * Licensed 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. * #L% */ package com.adobe.acs.commons.util.impl; import org.apache.commons.lang.StringUtils; import org.apache.felix.scr.annotations.Activate; import org.apache.felix.scr.annotations.Component; import org.apache.felix.scr.annotations.ConfigurationPolicy; import org.apache.felix.scr.annotations.Properties; import org.apache.felix.scr.annotations.Property; import org.apache.felix.scr.annotations.Service; import org.apache.sling.api.SlingHttpServletRequest; import org.apache.sling.api.SlingHttpServletResponse; import org.apache.sling.api.request.RequestDispatcherOptions; import org.apache.sling.api.servlets.SlingAllMethodsServlet; import org.apache.sling.commons.osgi.PropertiesUtil; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import javax.servlet.Servlet; import javax.servlet.ServletException; import java.io.IOException; import java.util.HashSet; import java.util.Map; import java.util.Set; @SuppressWarnings("serial") @Component(label = "ACS AEM Commons - Delegating Servlet", description = "Delegating Servlet enabling the unobtrusive delegate of Resource Types.", configurationFactory = true, policy = ConfigurationPolicy.REQUIRE, metatype = true, immediate = false) @Properties({ @Property(label = "Source Resource Types", description = "Requests matching the \"Source resource types, selectors, extensions and methods\" will be overlayed using the \"Target Resource Type\"", name = "sling.servlet.resourceTypes", cardinality = Integer.MAX_VALUE, value = { "" }), @Property(label = "Source Selectors", description = "Requests matching the \"Source resource types, selectors, extensions and methods\" will be overlayed using the \"Target Resource Type\"", name = "sling.servlet.selectors", cardinality = Integer.MAX_VALUE, value = { "" }), @Property(label = "Source Extensions", description = "Requests matching the \"Source resource types, selectors, extensions and methods\" will be overlayed using the \"Target Resource Type\"", name = "sling.servlet.extensions", cardinality = Integer.MAX_VALUE, value = { "html" }), @Property(label = "Source HTTP Methods", description = "Requests matching the \"Source resource types, selectors, extensions and methods\" will be overlayed using the \"Target Resource Type\"", name = "sling.servlet.methods", cardinality = Integer.MAX_VALUE, value = { "GET" }), @Property(name = "webconsole.configurationFactory.nameHint", value = "Target type: {prop.target-resource-type}") }) @Service(Servlet.class) public final class DelegatingServletFactoryImpl extends SlingAllMethodsServlet { protected static final Logger log = LoggerFactory.getLogger(DelegatingServletFactoryImpl.class); private static final String REQUEST_ATTR_DELEGATION_HISTORY = DelegatingServletFactoryImpl.class.getName() + "_History"; private static final String DEFAULT_TARGET_RESOURCE_TYPE = ""; private String targetResourceType = DEFAULT_TARGET_RESOURCE_TYPE; @Property(label = "Target Resource Type", description = "The resource type to proxy requests to.", value = DEFAULT_TARGET_RESOURCE_TYPE) public static final String PROP_TARGET_RESOURCE_TYPE = "prop.target-resource-type"; /** Safe HTTP Methods **/ public void doGeneric(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } public void doGet(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } public void doHead(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } public void doOptions(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } public void doTrace(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } /** Un-Safe HTTP Methods **/ public void doDelete(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } public void doPost(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } public void doPut(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { this.delegate(request, response); } /** * Delegates request through to the target resource type * * @param request * @param response */ private void delegate(final SlingHttpServletRequest request, final SlingHttpServletResponse response) throws ServletException { final RequestDispatcherOptions options = new RequestDispatcherOptions(); if (this.isCyclic(request, targetResourceType)) { log.error("Delegation Servlet creating a cycle for Target Resource Type: {}", targetResourceType); throw new ServletException("Cyclic delegation detected for " + targetResourceType); } if (StringUtils.isNotBlank(targetResourceType)) { log.debug("Delegating Request resource type with: {}", targetResourceType); options.setForceResourceType(targetResourceType); } else { log.warn("Delegating Servlet's \"Target Resource Type\" is blank or null"); } try { this.setDelegationHistory(request, targetResourceType); request.getRequestDispatcher(request.getResource(), options).forward(request, response); } catch (ServletException e) { log.error("Could not properly re-route request to delegate resource type: {}", targetResourceType); } catch (IOException e) { log.error("Could not properly re-route request to delegate resource type: {}", targetResourceType); } } /** * Determines if the Request is or will be cyclic * * @param request * @param targetResourceType * @return true is Request will cause a and infinite delegation cycle */ private boolean isCyclic(final SlingHttpServletRequest request, final String targetResourceType) { if (StringUtils.isBlank(targetResourceType)) { log.debug("Delegating Servlet's \"Target Resource Type\" is blank or null"); return true; } final Set<String> history = this.getDelegationHistory(request); if (history.contains(targetResourceType)) { log.debug("Delegating Servlet's \"Target Resource Type\" is been forwarded to previously"); return true; } return false; } /** * Retrieves the delegation history from the Request * * @param request * @return the delegation history set (of resource types previously targeted by this Servlet) */ @SuppressWarnings("unchecked") private Set<String> getDelegationHistory(final SlingHttpServletRequest request) { Set<String> history = new HashSet<String>(); final Object tmp = request.getAttribute(REQUEST_ATTR_DELEGATION_HISTORY); if (history.getClass().isInstance(tmp)) { return (Set<String>) tmp; } else { return history; } } /** * Sets the targetResourceType as part of the delegation history and adds update history set to the Request * * @param request * @param targetResourceType */ private void setDelegationHistory(final SlingHttpServletRequest request, final String targetResourceType) { final Set<String> history = this.getDelegationHistory(request); history.add(targetResourceType); request.setAttribute(REQUEST_ATTR_DELEGATION_HISTORY, history); } @Activate protected void activate(final Map<String, String> config) { targetResourceType = PropertiesUtil.toString(config.get(PROP_TARGET_RESOURCE_TYPE), ""); if (StringUtils.isBlank(targetResourceType)) { throw new IllegalArgumentException("Target Resource Type must NOT be blank"); } log.debug("Target Resource Type: {}", targetResourceType); } }