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.ajax; import java.util.Collection; import java.util.Collections; import java.util.HashSet; import java.util.LinkedList; import java.util.List; import java.util.Map; import java.util.Set; import org.apache.wicket.Application; import org.apache.wicket.Component; import org.apache.wicket.MarkupContainer; import org.apache.wicket.Page; import org.apache.wicket.core.request.handler.PageProvider; import org.apache.wicket.core.request.handler.RenderPageRequestHandler; import org.apache.wicket.core.request.handler.logger.PageLogData; import org.apache.wicket.event.Broadcast; import org.apache.wicket.markup.head.IHeaderResponse; import org.apache.wicket.page.PartialPageUpdate; import org.apache.wicket.page.XmlPartialPageUpdate; import org.apache.wicket.request.IRequestCycle; import org.apache.wicket.request.IRequestHandler; import org.apache.wicket.request.Response; import org.apache.wicket.request.component.IRequestablePage; import org.apache.wicket.request.cycle.RequestCycle; import org.apache.wicket.request.http.WebRequest; import org.apache.wicket.request.http.WebResponse; import org.apache.wicket.request.mapper.parameter.PageParameters; import org.apache.wicket.response.StringResponse; import org.apache.wicket.response.filter.IResponseFilter; import org.apache.wicket.util.encoding.UrlDecoder; import org.apache.wicket.util.lang.Args; import org.apache.wicket.util.lang.Classes; import org.apache.wicket.util.string.AppendingStringBuffer; import org.apache.wicket.util.string.Strings; import org.apache.wicket.util.visit.IVisit; import org.apache.wicket.util.visit.IVisitor; /** * A request target that produces ajax response envelopes used on the client side to update * component markup as well as evaluate arbitrary javascript. * <p> * A component whose markup needs to be updated should be added to this target via * AjaxRequestTarget#add(Component) method. Its body will be rendered and added to the envelope when * the target is processed, and refreshed on the client side when the ajax response is received. * <p> * It is important that the component whose markup needs to be updated contains an id attribute in * the generated markup that is equal to the value retrieved from Component#getMarkupId(). This can * be accomplished by either setting the id attribute in the html template, or using an attribute * modifier that will add the attribute with value Component#getMarkupId() to the tag ( such as * MarkupIdSetter ) * <p> * Any javascript that needs to be evaluated on the client side can be added using * AjaxRequestTarget#append/prependJavaScript(String). For example, this feature can be useful when * it is desirable to link component update with some javascript effects. * <p> * The target provides a listener interface {@link AjaxRequestTarget.IListener} that can be used to * add code that responds to various target events by adding listeners via * {@link #addListener(AjaxRequestTarget.IListener)} * * @since 1.2 * * @author Igor Vaynberg (ivaynberg) * @author Eelco Hillenius */ public class AjaxRequestHandler implements AjaxRequestTarget { /** * Collector of page updates. */ private final PartialPageUpdate update; /** a list of listeners */ private List<AjaxRequestTarget.IListener> listeners = null; /** */ private final Set<ITargetRespondListener> respondListeners = new HashSet<>(); /** see https://issues.apache.org/jira/browse/WICKET-3564 */ protected transient boolean respondersFrozen; protected transient boolean listenersFrozen; /** The associated Page */ private final Page page; private PageLogData logData; /** * Constructor * * @param page * the currently active page */ public AjaxRequestHandler(final Page page) { this.page = Args.notNull(page, "page"); update = new XmlPartialPageUpdate(page) { /** * Freezes the {@link AjaxRequestHandler#listeners} before firing the event and * un-freezes them afterwards to allow components to add more * {@link AjaxRequestTarget.IListener}s for the second event. */ @Override protected void onBeforeRespond(final Response response) { listenersFrozen = true; if (listeners != null) { for (AjaxRequestTarget.IListener listener : listeners) { listener.onBeforeRespond(markupIdToComponent, AjaxRequestHandler.this); } } listenersFrozen = false; } /** * Freezes the {@link AjaxRequestHandler#listeners}, and does not un-freeze them as the * events will have been fired by now. * * @param response * the response to write to */ @Override protected void onAfterRespond(final Response response) { listenersFrozen = true; // invoke onafterresponse event on listeners if (listeners != null) { final Map<String, Component> components = Collections.unmodifiableMap(markupIdToComponent); // create response that will be used by listeners to append // javascript final AjaxRequestTarget.IJavaScriptResponse jsresponse = new AjaxRequestTarget.IJavaScriptResponse() { @Override public void addJavaScript(String script) { writeNormalEvaluations(response, Collections.<CharSequence>singleton(script)); } }; for (AjaxRequestTarget.IListener listener : listeners) { listener.onAfterRespond(components, jsresponse); } } } }; } /** * @see org.apache.wicket.core.request.handler.IPageRequestHandler#getPage() */ @Override public Page getPage() { return page; } @Override public void addListener(AjaxRequestTarget.IListener listener) throws IllegalStateException { Args.notNull(listener, "listener"); assertListenersNotFrozen(); if (listeners == null) { listeners = new LinkedList<>(); } if (!listeners.contains(listener)) { listeners.add(listener); } } @Override public final void addChildren(MarkupContainer parent, Class<?> childCriteria) { Args.notNull(parent, "parent"); Args.notNull(childCriteria, "childCriteria"); parent.visitChildren(childCriteria, new IVisitor<Component, Void>() { @Override public void component(final Component component, final IVisit<Void> visit) { add(component); visit.dontGoDeeper(); } }); } @Override public void add(Component... components) { for (final Component component : components) { Args.notNull(component, "component"); if (component.getOutputMarkupId() == false && !(component instanceof Page)) { throw new IllegalArgumentException( "Cannot update component that does not have setOutputMarkupId property set to true. Component: " + component.toString()); } add(component, component.getMarkupId()); } } @Override public void add(Component component, String markupId) { update.add(component, markupId); } @Override public final Collection<? extends Component> getComponents() { return update.getComponents(); } @Override public final void focusComponent(Component component) { if (component != null && component.getOutputMarkupId() == false) { throw new IllegalArgumentException( "cannot update component that does not have setOutputMarkupId property set to true. Component: " + component.toString()); } final String id = component != null ? ("'" + component.getMarkupId() + "'") : "null"; appendJavaScript("Wicket.Focus.setFocusOnId(" + id + ");"); } @Override public final void appendJavaScript(CharSequence javascript) { update.appendJavaScript(javascript); } /** * @see org.apache.wicket.core.request.handler.IPageRequestHandler#detach(org.apache.wicket.request.IRequestCycle) */ @Override public void detach(final IRequestCycle requestCycle) { if (logData == null) { logData = new PageLogData(page); } update.detach(requestCycle); } /** * @see java.lang.Object#equals(java.lang.Object) */ @Override public boolean equals(final Object obj) { if (obj instanceof AjaxRequestHandler) { AjaxRequestHandler that = (AjaxRequestHandler) obj; return update.equals(that.update); } return false; } /** * @see java.lang.Object#hashCode() */ @Override public int hashCode() { int result = "AjaxRequestHandler".hashCode(); result += update.hashCode() * 17; return result; } @Override public final void prependJavaScript(CharSequence javascript) { update.prependJavaScript(javascript); } @Override public void registerRespondListener(ITargetRespondListener listener) { assertRespondersNotFrozen(); respondListeners.add(listener); } /** * @see org.apache.wicket.core.request.handler.IPageRequestHandler#respond(org.apache.wicket.request.IRequestCycle) */ @Override public final void respond(final IRequestCycle requestCycle) { final RequestCycle rc = (RequestCycle) requestCycle; final WebResponse response = (WebResponse) requestCycle.getResponse(); if (shouldRedirectToPage(requestCycle)) { // the page itself has been added to the request target, we simply issue a redirect // back to the page IRequestHandler handler = new RenderPageRequestHandler(new PageProvider(page)); final String url = rc.urlFor(handler).toString(); response.sendRedirect(url); return; } respondersFrozen = true; for (ITargetRespondListener listener : respondListeners) { listener.onTargetRespond(this); } final Application app = page.getApplication(); page.send(app, Broadcast.BREADTH, this); // Determine encoding final String encoding = app.getRequestCycleSettings().getResponseRequestEncoding(); // Set content type based on markup type for page update.setContentType(response, encoding); // Make sure it is not cached by a client response.disableCaching(); final StringResponse bodyResponse = new StringResponse(); update.writeTo(bodyResponse, encoding); CharSequence filteredResponse = invokeResponseFilters(bodyResponse); response.write(filteredResponse); } private boolean shouldRedirectToPage(IRequestCycle requestCycle) { if (update.containsPage()) { return true; } if (((WebRequest) requestCycle.getRequest()).isAjax() == false) { // the request was not sent by wicket-ajax.js - this can happen when an Ajax request was // intercepted with #redirectToInterceptPage() and then the original request is re-sent // by the browser on a subsequent #continueToOriginalDestination() return true; } return false; } /** * Runs the configured {@link IResponseFilter}s over the constructed Ajax response * * @param contentResponse * the Ajax {@link Response} body * @return filtered response */ private AppendingStringBuffer invokeResponseFilters(final StringResponse contentResponse) { AppendingStringBuffer responseBuffer = new AppendingStringBuffer(contentResponse.getBuffer()); List<IResponseFilter> responseFilters = Application.get().getRequestCycleSettings().getResponseFilters(); if (responseFilters != null) { for (IResponseFilter filter : responseFilters) { responseBuffer = filter.filter(responseBuffer); } } return responseBuffer; } /** * @see java.lang.Object#toString() */ @Override public String toString() { return "[AjaxRequestHandler@" + hashCode() + " responseObject [" + update + "]"; } @Override public IHeaderResponse getHeaderResponse() { return update.getHeaderResponse(); } /** * @return the markup id of the focused element in the browser */ @Override public String getLastFocusedElementId() { WebRequest request = (WebRequest) page.getRequest(); String id = request.getHeader("Wicket-FocusedElementId"); // WICKET-6568 might contain non-ASCII return Strings.isEmpty(id) ? null : UrlDecoder.QUERY_INSTANCE.decode(id, request.getCharset()); } @Override public Class<? extends IRequestablePage> getPageClass() { return page.getPageClass(); } @Override public Integer getPageId() { return page.getPageId(); } @Override public PageParameters getPageParameters() { return page.getPageParameters(); } @Override public final boolean isPageInstanceCreated() { return true; } @Override public final Integer getRenderCount() { return page.getRenderCount(); } @Override public PageLogData getLogData() { return logData; } private void assertNotFrozen(boolean frozen, Class<?> clazz) { if (frozen) { throw new IllegalStateException(Classes.simpleName(clazz) + "s can no longer be added"); } } private void assertRespondersNotFrozen() { assertNotFrozen(respondersFrozen, AjaxRequestTarget.ITargetRespondListener.class); } private void assertListenersNotFrozen() { assertNotFrozen(listenersFrozen, AjaxRequestTarget.IListener.class); } }