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.handler; import org.apache.wicket.Component; import org.apache.wicket.IRequestListener; import org.apache.wicket.Page; import org.apache.wicket.WicketRuntimeException; import org.apache.wicket.behavior.Behavior; import org.apache.wicket.core.request.handler.RenderPageRequestHandler.RedirectPolicy; import org.apache.wicket.core.request.handler.logger.ListenerLogData; import org.apache.wicket.request.ILoggableRequestHandler; import org.apache.wicket.request.IRequestCycle; import org.apache.wicket.request.component.IRequestableComponent; import org.apache.wicket.request.component.IRequestablePage; import org.apache.wicket.request.http.WebRequest; import org.apache.wicket.request.mapper.parameter.PageParameters; import org.apache.wicket.util.lang.Args; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Request handler that invokes an {@link IRequestListener} on component or behavior and renders page afterwards. * * @author Matej Knopp */ public class ListenerRequestHandler implements IPageRequestHandler, IComponentRequestHandler, ILoggableRequestHandler { private static final Logger LOG = LoggerFactory.getLogger(ListenerRequestHandler.class); private final IPageAndComponentProvider pageComponentProvider; private final Integer behaviorId; private ListenerLogData logData; /** * Construct. * * @param pageComponentProvider * @param behaviorIndex */ public ListenerRequestHandler(IPageAndComponentProvider pageComponentProvider, Integer behaviorIndex) { Args.notNull(pageComponentProvider, "pageComponentProvider"); this.pageComponentProvider = pageComponentProvider; behaviorId = behaviorIndex; } /** * Construct. * * @param pageComponentProvider */ public ListenerRequestHandler(PageAndComponentProvider pageComponentProvider) { this(pageComponentProvider, null); } public boolean includeRenderCount() { if (behaviorId == null) { return ((IRequestListener) getComponent()).rendersPage(); } else { return ((IRequestListener) getComponent().getBehaviorById(getBehaviorIndex())).rendersPage(); } } @Override public IRequestableComponent getComponent() { return pageComponentProvider.getComponent(); } @Override public IRequestablePage getPage() { return pageComponentProvider.getPageInstance(); } @Override public Class<? extends IRequestablePage> getPageClass() { return pageComponentProvider.getPageClass(); } @Override public Integer getPageId() { return pageComponentProvider.getPageId(); } @Override public PageParameters getPageParameters() { return pageComponentProvider.getPageParameters(); } @Override public void detach(IRequestCycle requestCycle) { if (logData == null) { logData = new ListenerLogData(pageComponentProvider, behaviorId); } pageComponentProvider.detach(); } /** * Index of target behavior or <code>null</code> if component is the target. * * @return behavior index or <code>null</code> */ public Integer getBehaviorIndex() { return behaviorId; } @Override public void respond(final IRequestCycle requestCycle) { final IRequestablePage page = getPage(); final boolean freshPage = pageComponentProvider.doesProvideNewPage(); final boolean isAjax = ((WebRequest) requestCycle.getRequest()).isAjax(); IRequestableComponent component; try { component = getComponent(); } catch (ComponentNotFoundException e) { // either the page is stateless and the component we are looking for is not added in the // constructor // or the page is stateful+stale and a new instances was created by pageprovider // we denote this by setting component to null component = null; } if ((component == null && !freshPage) || (component != null && component.getPage() != page)) { throw new ComponentNotFoundException( "Component '" + getComponentPath() + "' has been removed from page."); } if (page instanceof Page) { // initialize the page to be able to check whether it is stateless ((Page) page).internalInitialize(); } RedirectPolicy policy = page.isPageStateless() ? RedirectPolicy.NEVER_REDIRECT : RedirectPolicy.AUTO_REDIRECT; boolean blockIfExpired = component != null && !component.canCallListenerAfterExpiry(); boolean lateComponent = component == null && freshPage; if ((pageComponentProvider.wasExpired() && blockIfExpired) || lateComponent) { // A request listener is invoked on an expired page or the component couldn't be // determined. The best we can do is to re-paint the newly constructed page. // Reference: WICKET-4454, WICKET-6288 if (LOG.isDebugEnabled()) { LOG.debug( "An IRequestListener was called but its page/component({}) couldn't be resolved. " + "Scheduling re-create of the page and ignoring the listener interface...", getComponentPath()); } if (isAjax) { policy = RedirectPolicy.ALWAYS_REDIRECT; } requestCycle.scheduleRequestHandlerAfterCurrent( new RenderPageRequestHandler(new PageProvider(page), policy)); return; } invokeListener(requestCycle, policy, isAjax); } private void invokeListener(IRequestCycle requestCycle, RedirectPolicy policy, boolean ajax) { if (getBehaviorIndex() == null) { invoke(requestCycle, policy, ajax, getComponent()); } else { try { Behavior behavior = getComponent().getBehaviorById(behaviorId); invoke(requestCycle, policy, ajax, getComponent(), behavior); } catch (IndexOutOfBoundsException e) { throw new WicketRuntimeException("Couldn't find component behavior.", e); } } } /** * Invokes a given interface on a component. * * @param rcomponent * The component * * @throws ListenerInvocationNotAllowedException * when listener invocation attempted on a component that does not allow it */ private final void invoke(final IRequestCycle requestCycle, RedirectPolicy policy, boolean ajax, final IRequestableComponent rcomponent) { // we are in Wicket core land final Component component = (Component) rcomponent; if (!component.canCallListener()) { // just return so that we have a silent fail and just re-render the // page LOG.info("component not enabled or visible; ignoring call. Component: " + component); throw new ListenerInvocationNotAllowedException(component, null, "Component rejected interface invocation"); } internalInvoke(requestCycle, policy, ajax, component, component); } /** * Invokes a given interface on a component's behavior. * * @param rcomponent * The component * @param behavior * @throws ListenerInvocationNotAllowedException * when listener invocation attempted on a component that does not allow it */ private final void invoke(final IRequestCycle requestCycle, RedirectPolicy policy, boolean ajax, final IRequestableComponent rcomponent, final Behavior behavior) { // we are in Wicket core land final Component component = (Component) rcomponent; if (!behavior.canCallListener(component)) { LOG.warn("behavior not enabled; ignore call. Behavior {} at component {}", behavior, component); throw new ListenerInvocationNotAllowedException(component, behavior, "Behavior rejected interface invocation. "); } internalInvoke(requestCycle, policy, ajax, component, behavior); } private void internalInvoke(final IRequestCycle requestCycle, RedirectPolicy policy, boolean ajax, final Component component, final Object target) { // save a reference to the page because the component can be removed // during the invocation of the listener and thus lose its parent Page page = component.getPage(); // initialization is required for stateless pages if (!page.isInitialized()) { page.internalInitialize(); } IRequestListener requestListener = (IRequestListener) target; if (requestListener.rendersPage() && !ajax) { // schedule page render after current request handler is done. this can be // overridden during invocation of listener // method (i.e. by calling RequestCycle#setResponsePage) requestCycle.scheduleRequestHandlerAfterCurrent( new RenderPageRequestHandler(new PageProvider(page), policy)); } requestListener.onRequest(); } @Override public final boolean isPageInstanceCreated() { return pageComponentProvider.hasPageInstance(); } @Override public final String getComponentPath() { return pageComponentProvider.getComponentPath(); } @Override public final Integer getRenderCount() { return pageComponentProvider.getRenderCount(); } @Override public ListenerLogData getLogData() { return logData; } }