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.markup.head; import java.util.Objects; import org.apache.wicket.core.request.handler.IPartialPageRequestHandler; import org.apache.wicket.core.util.string.CssUtils; import org.apache.wicket.request.Response; import org.apache.wicket.request.cycle.RequestCycle; import org.apache.wicket.request.mapper.parameter.PageParameters; import org.apache.wicket.request.resource.ResourceReference; import org.apache.wicket.util.lang.Args; import org.apache.wicket.util.string.Strings; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Base class for all {@link HeaderItem}s that represent stylesheets. This class mainly contains * factory methods. * * @author papegaaij */ public abstract class CssHeaderItem extends HeaderItem { private static final long serialVersionUID = 1L; private static final Logger logger = LoggerFactory.getLogger(CssHeaderItem.class); /** * The condition to use for Internet Explorer conditional comments. E.g. "IE 7". * {@code null} or empty string for no condition. * * <strong>Warning</strong>: the conditional comments don't work when injected dynamically * with JavaScript (i.e. in Ajax response). An alternative solution is to use user agent sniffing * at the server side: * <code><pre> * public void renderHead(IHeaderResponse response) { * WebClientInfo clientInfo = (WebClientInfo) getSession().getClientInfo(); * ClientProperties properties = clientInfo.getProperties(); * if (properties.isBrowserInternetExplorer() && properties.getBrowserVersionMajor() >= 8) { * response.renderCSSReference(new PackageResourceReference(MyPage.class, "my-conditional.css" )); * } * } * </pre></code> */ private final String condition; private String markupId; protected CssHeaderItem(String condition) { this.condition = condition; } /** * @return an optional markup id for the <link> HTML element that will be rendered * for this header item */ public String getId() { return markupId; } /** * @param markupId * an optional markup id for this header item * @return {@code this} object, for method chaining */ public CssHeaderItem setId(String markupId) { this.markupId = markupId; return this; } /** * @return the condition to use for Internet Explorer conditional comments. E.g. "IE 7". */ public String getCondition() { return condition; } /** * Creates a {@link CssReferenceHeaderItem} for the given reference. * * @param reference * a reference to a CSS resource * @return A newly created {@link CssReferenceHeaderItem} for the given reference. */ public static CssReferenceHeaderItem forReference(ResourceReference reference) { return forReference(reference, null); } /** * Creates a {@link CssReferenceHeaderItem} for the given reference. * * @param reference * a reference to a CSS resource * @param media * the media type for this CSS ("print", "screen", etc.) * @return A newly created {@link CssReferenceHeaderItem} for the given reference. */ public static CssReferenceHeaderItem forReference(ResourceReference reference, String media) { return forReference(reference, null, media); } /** * Creates a {@link CssReferenceHeaderItem} for the given reference. * * @param reference * a reference to a CSS resource * @param pageParameters * the parameters for this CSS resource reference * @param media * the media type for this CSS ("print", "screen", etc.) * @return A newly created {@link CssReferenceHeaderItem} for the given reference. */ public static CssReferenceHeaderItem forReference(ResourceReference reference, PageParameters pageParameters, String media) { return forReference(reference, pageParameters, media, null); } /** * Creates a {@link CssReferenceHeaderItem} for the given reference. * * <strong>Warning</strong>: the conditional comments don't work when injected dynamically * with JavaScript (i.e. in Ajax response). An alternative solution is to use user agent sniffing * at the server side: * <code><pre> * public void renderHead(IHeaderResponse response) { * WebClientInfo clientInfo = (WebClientInfo) getSession().getClientInfo(); * ClientProperties properties = clientInfo.getProperties(); * if (properties.isBrowserInternetExplorer() && properties.getBrowserVersionMajor() >= 8) { * response.renderCSSReference(new PackageResourceReference(MyPage.class, "my-conditional.css" )); * } * } * </pre></code> * * @param reference * a reference to a CSS resource * @param pageParameters * the parameters for this CSS resource reference * @param media * the media type for this CSS ("print", "screen", etc.) * @param condition * the condition to use for Internet Explorer conditional comments. E.g. "IE 7". * @return A newly created {@link CssReferenceHeaderItem} for the given reference. */ public static CssReferenceHeaderItem forReference(ResourceReference reference, PageParameters pageParameters, String media, String condition) { return new CssReferenceHeaderItem(reference, pageParameters, media, condition); } /** * Creates a {@link CssReferenceHeaderItem} for the given reference. * * <strong>Warning</strong>: the conditional comments don't work when injected dynamically with * JavaScript (i.e. in Ajax response). An alternative solution is to use user agent sniffing at * the server side: <code><pre> * public void renderHead(IHeaderResponse response) { * WebClientInfo clientInfo = (WebClientInfo) getSession().getClientInfo(); * ClientProperties properties = clientInfo.getProperties(); * if (properties.isBrowserInternetExplorer() && properties.getBrowserVersionMajor() >= 8) { * response.renderCSSReference(new PackageResourceReference(MyPage.class, "my-conditional.css" )); * } * } * </pre></code> * * @param reference * a reference to a CSS resource * @param pageParameters * the parameters for this CSS resource reference * @param media * the media type for this CSS ("print", "screen", etc.) * @param condition * the condition to use for Internet Explorer conditional comments. E.g. "IE 7". * @param rel * the rel attribute content * @return A newly created {@link CssReferenceHeaderItem} for the given reference. */ public static CssReferenceHeaderItem forReference(ResourceReference reference, PageParameters pageParameters, String media, String condition, String rel) { return new CssReferenceHeaderItem(reference, pageParameters, media, condition, rel); } /** * Creates a {@link CssContentHeaderItem} for the given content. * * @param css * css content to be rendered. * @param id * unique id for the <style> element. This can be <code>null</code>, however in * that case the ajax header contribution can't detect duplicate CSS fragments. * @return A newly created {@link CssContentHeaderItem} for the given content. */ public static CssContentHeaderItem forCSS(CharSequence css, String id) { return forCSS(css, id, null); } /** * Creates a {@link CssContentHeaderItem} for the given content. * * <strong>Warning</strong>: the conditional comments don't work when injected dynamically * with JavaScript (i.e. in Ajax response). An alternative solution is to use user agent sniffing * at the server side: * <code><pre> * public void renderHead(IHeaderResponse response) { * WebClientInfo clientInfo = (WebClientInfo) getSession().getClientInfo(); * ClientProperties properties = clientInfo.getProperties(); * if (properties.isBrowserInternetExplorer() && properties.getBrowserVersionMajor() >= 8) { * response.renderCSSReference(new PackageResourceReference(MyPage.class, "my-conditional.css" )); * } * } * </pre></code> * * @param css * css content to be rendered. * @param id * unique id for the <style> element. This can be <code>null</code>, however in * that case the ajax header contribution can't detect duplicate CSS fragments. * @param condition * the condition to use for Internet Explorer conditional comments. E.g. "IE 7". * @return A newly created {@link CssContentHeaderItem} for the given content. */ public static CssContentHeaderItem forCSS(CharSequence css, String id, String condition) { return new CssContentHeaderItem(css, id, condition); } /** * Creates a {@link CssUrlReferenceHeaderItem} for the given url. * * @param url * context-relative url of the CSS resource * @return A newly created {@link CssUrlReferenceHeaderItem} for the given url. */ public static CssUrlReferenceHeaderItem forUrl(String url) { return forUrl(url, null); } /** * Creates a {@link CssUrlReferenceHeaderItem} for the given url. * * @param url * context-relative url of the CSS resource * @param media * the media type for this CSS ("print", "screen", etc.) * @return A newly created {@link CssUrlReferenceHeaderItem} for the given url. */ public static CssUrlReferenceHeaderItem forUrl(String url, String media) { return forUrl(url, media, null); } /** * Creates a {@link CssUrlReferenceHeaderItem} for the given url. * * <strong>Warning</strong>: the conditional comments don't work when injected dynamically * with JavaScript (i.e. in Ajax response). An alternative solution is to use user agent sniffing * at the server side: * <code><pre> * public void renderHead(IHeaderResponse response) { * WebClientInfo clientInfo = (WebClientInfo) getSession().getClientInfo(); * ClientProperties properties = clientInfo.getProperties(); * if (properties.isBrowserInternetExplorer() && properties.getBrowserVersionMajor() >= 8) { * response.renderCSSReference(new PackageResourceReference(MyPage.class, "my-conditional.css" )); * } * } * </pre></code> * * @param url * context-relative url of the CSS resource * @param media * the media type for this CSS ("print", "screen", etc.) * @param condition * the condition to use for Internet Explorer conditional comments. E.g. "IE 7". * @return A newly created {@link CssUrlReferenceHeaderItem} for the given url. */ public static CssUrlReferenceHeaderItem forUrl(String url, String media, String condition) { return new CssUrlReferenceHeaderItem(url, media, condition); } /** * Creates a {@link CssUrlReferenceHeaderItem} for the given url. * * <strong>Warning</strong>: the conditional comments don't work when injected dynamically with * JavaScript (i.e. in Ajax response). An alternative solution is to use user agent sniffing at * the server side: <code><pre> * public void renderHead(IHeaderResponse response) { * WebClientInfo clientInfo = (WebClientInfo) getSession().getClientInfo(); * ClientProperties properties = clientInfo.getProperties(); * if (properties.isBrowserInternetExplorer() && properties.getBrowserVersionMajor() >= 8) { * response.renderCSSReference(new PackageResourceReference(MyPage.class, "my-conditional.css" )); * } * } * </pre></code> * * @param url * context-relative url of the CSS resource * @param media * the media type for this CSS ("print", "screen", etc.) * @param condition * the condition to use for Internet Explorer conditional comments. E.g. "IE 7". * @param rel * the rel attribute content * @return A newly created {@link CssUrlReferenceHeaderItem} for the given url. */ public static CssUrlReferenceHeaderItem forUrl(String url, String media, String condition, String rel) { return new CssUrlReferenceHeaderItem(url, media, condition, rel); } protected final void internalRenderCSSReference(Response response, String url, String media, String condition, String rel) { Args.notEmpty(url, "url"); boolean hasCondition = Strings.isEmpty(condition) == false; if (hasCondition) { if (RequestCycle.get().find(IPartialPageRequestHandler.class).isPresent()) { // WICKET-4894 logger.warn("IE CSS engine doesn't support dynamically injected links in " + "conditional comments. See the javadoc of IHeaderResponse for alternative solution."); } response.write("<!--[if "); response.write(condition); response.write("]>"); } CssUtils.writeLinkUrl(response, url, media, getId(), rel); if (hasCondition) { response.write("<![endif]-->"); } response.write("\n"); } @Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false; CssHeaderItem that = (CssHeaderItem) o; return Objects.equals(condition, that.condition) && Objects.equals(markupId, that.markupId); } @Override public int hashCode() { return Objects.hash(condition, markupId); } }