📄 htmlheadercontainer.java
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/* * 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.markup.html.internal;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;import org.apache.wicket.Component;import org.apache.wicket.MarkupContainer;import org.apache.wicket.RequestContext;import org.apache.wicket.Response;import org.apache.wicket.markup.ComponentTag;import org.apache.wicket.markup.MarkupStream;import org.apache.wicket.markup.html.IHeaderResponse;import org.apache.wicket.markup.html.WebMarkupContainer;import org.apache.wicket.response.StringResponse;/** * The HtmlHeaderContainer is automatically created and added to the component hierarchy by a * HtmlHeaderResolver instance. HtmlHeaderContainer tries to handle/render the >head> tag and * its body. However depending on the parent component, the behavior must be different. E.g. if * parent component is a Page all components of the page's hierarchy must be asked if they have * something to contribute to the <head> section of the html response. If yes, it must * <b>immediately</b> be rendered. * <p> * <head> regions may contain additional wicket components, which can be added by means of * add(Component) as usual. * <p> * <wicket:head> tags are handled by simple WebMarkupContainers also created by a * HtmlHeaderResolver. * <p> * <ul> * <li> <head> will be inserted in output automatically if required</li> * <li> <head> is <b>not</b> a wicket specific tag and you must use add() to add components * referenced in body of the head tag</li> * <li> <head> is supported by panels, borders and inherited markup, but is <b>not</b> copied * to the output. They are for previewability only (except on Pages)</li> * <li> <wicket:head> does not make sense in page markup (but does in inherited page markup)</li> * <li> <wicket:head> makes sense in Panels, Borders and inherited markup (of Panels, Borders * and Pages)</li> * <li> components within <wicket:head> must be added by means of add(), like always with * Wicket. No difference.</li> * <li> <wicket:head> and it's content is copied to the output. Components contained in * <org.apache.wicket.head> are rendered as usual</li> * </ul> * * @author Juergen Donnerstag */public class HtmlHeaderContainer extends WebMarkupContainer{ private static final long serialVersionUID = 1L; /** * wicket:head tags (components) must only be added once. To allow for a little bit more * control, each wicket:head has an associated scope which by default is equal to the java class * name directly associated with the markup which contains the wicket:head. It can be modified * by means of the scope attribute. */ private transient Map renderedComponentsPerScope; /** * Header response that is responsible for filtering duplicate contributions. */ private transient IHeaderResponse headerResponse = null; /** * Construct * * @see Component#Component(String) */ public HtmlHeaderContainer(final String id) { super(id); // We will render the tags manually, because if no component asked to // contribute to the header, the tags will not be printed either. // No contribution usually only happens if none of the components // including the page does have a <head> or <wicket:head> tag. setRenderBodyOnly(true); setAuto(true); } /** * First render the body of the component. And if it is the header component of a Page (compared * to a Panel or Border), than get the header sections from all component in the hierarchy and * render them as well. * * @see org.apache.wicket.MarkupContainer#onComponentTagBody(org.apache.wicket.markup.MarkupStream, * org.apache.wicket.markup.ComponentTag) */ protected final void onComponentTagBody(MarkupStream markupStream, ComponentTag openTag) { // We are able to automatically add <head> to the page if it is // missing. But we only want to add it, if we have content to be // written to its body. Thus we first write the output into a // StringResponse and if not empty, we copy it to the original // web response. // Temporarily replace the web response with a String response final Response webResponse = getResponse(); try { final StringResponse response = new StringResponse(); getRequestCycle().setResponse(response); IHeaderResponse headerResponse = getHeaderResponse(); if (!response.equals(headerResponse.getResponse())) { getRequestCycle().setResponse(headerResponse.getResponse()); } // In any case, first render the header section directly associated // with the markup super.onComponentTagBody(markupStream, openTag); // Render all header sections of all components on the page renderHeaderSections(getPage(), this); getHeaderResponse().close(); // Automatically add <head> if necessary CharSequence output = response.getBuffer(); if (output.length() > 0) { if (output.charAt(0) == '\r') { for (int i = 2; i < output.length(); i += 2) { char ch = output.charAt(i); if (ch != '\r') { output = output.subSequence(i - 2, output.length()); break; } } } else if (output.charAt(0) == '\n') { for (int i = 1; i < output.length(); i++) { char ch = output.charAt(i); if (ch != '\n') { output = output.subSequence(i - 1, output.length()); break; } } } } if (output.length() > 0) { webResponse.write("<head>"); webResponse.write(output); webResponse.write("</head>"); } } finally { // Restore the original response getRequestCycle().setResponse(webResponse); } } /** * Ask all child components of the Page if they have something to contribute to the <head> * section of the HTML output. Every component interested must implement IHeaderContributor. * <p> * Note: HtmlHeaderContainer will be removed from the component hierarchy at the end of the * request (@see #onEndRequest()) and thus can not transport status from one request to the * next. This is true for all components added to the header. * * @param page * Usually it is the page object, but there might also be that a WebMarkupContainer * has been attached to the <html> tag * @param container * The header component container */ private final void renderHeaderSections(final MarkupContainer page, final HtmlHeaderContainer container) { page.renderHead(container); // Make sure all Components interested in contributing to the header // and there attached behaviors are asked. page.visitChildren(new IVisitor() { /** * @see org.apache.wicket.Component.IVisitor#component(org.apache.wicket.Component) */ public Object component(Component component) { if (component.isVisible()) { component.renderHead(container); return IVisitor.CONTINUE_TRAVERSAL; } else { return IVisitor.CONTINUE_TRAVERSAL_BUT_DONT_GO_DEEPER; } } }); } /** * @see org.apache.wicket.MarkupContainer#isTransparentResolver() */ public boolean isTransparentResolver() { return true; } /** * Check if the header component is ok to render within the scope given. * * @param scope * The scope of the header component * @param id * The component's id * @return true, if the component ok to render */ public final boolean okToRenderComponent(final String scope, final String id) { if (renderedComponentsPerScope == null) { renderedComponentsPerScope = new HashMap(); } // if (scope == null) // { // scope = header.getMarkupStream().getContainerClass().getName(); // } List componentScope = (List)renderedComponentsPerScope.get(scope); if (componentScope == null) { componentScope = new ArrayList(); renderedComponentsPerScope.put(scope, componentScope); } if (componentScope.contains(id)) { return false; } componentScope.add(id); return true; } protected void onDetach() { super.onDetach(); renderedComponentsPerScope = null; headerResponse = null; } /** * Factory method for creating header response * * @return new header response */ protected IHeaderResponse newHeaderResponse() { IHeaderResponse headerResponse = RequestContext.get().getHeaderResponse(); if (headerResponse == null) { // no (portlet) headerResponse override, create a default one headerResponse = new HeaderResponse() { protected Response getRealResponse() { return HtmlHeaderContainer.this.getResponse(); } }; } return headerResponse; } /** * Returns the header response. * * @return header response */ public IHeaderResponse getHeaderResponse() { if (headerResponse == null) { headerResponse = newHeaderResponse(); } return headerResponse; }}⌨️ 快捷键说明
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