Java tutorial
/* * Copyright 2000-2018 Vaadin Ltd. * * 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. */ package com.vaadin.ui; import static java.nio.charset.StandardCharsets.UTF_8; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.Collections; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Map.Entry; import java.util.Set; import org.jsoup.nodes.Element; import com.vaadin.server.JsonPaintTarget; import com.vaadin.server.PaintException; import com.vaadin.server.PaintTarget; import com.vaadin.shared.ui.customlayout.CustomLayoutState; import com.vaadin.ui.declarative.DesignContext; /** * <p> * A container component with freely designed layout and style. The layout * consists of items with textually represented locations. Each item contains * one sub-component, which can be any Vaadin component, such as a layout. The * adapter and theme are responsible for rendering the layout with a given style * by placing the items in the defined locations. * </p> * * <p> * The placement of the locations is not fixed - different themes can define the * locations in a way that is suitable for them. One typical example would be to * create visual design for a web site as a custom layout: the visual design * would define locations for "menu", "body", and "title", for example. The * layout would then be implemented as an HTML template for each theme. * </p> * * <p> * A location is identified with the attribute "data-location" or "location" * which has the location name as its value. * </p> * * <p> * The default theme handles the styles that are not defined by drawing the * subcomponents just as in OrderedLayout. * </p> * * @author Vaadin Ltd. * @since 3.0 */ @SuppressWarnings("serial") public class CustomLayout extends AbstractLayout implements LegacyComponent { private static final int BUFFER_SIZE = 10000; /** * Custom layout slots containing the components. */ private final Map<String, Component> slots = new HashMap<>(); /** * Default constructor only used by subclasses. Subclasses are responsible * for setting the appropriate fields. Either * {@link #setTemplateName(String)}, that makes layout fetch the template * from theme, or {@link #setTemplateContents(String)}. * * @since 7.5.0 */ public CustomLayout() { setWidth(100, Unit.PERCENTAGE); } /** * Constructs a custom layout with the template given in the stream. * * @param templateStream * Stream containing template data. Must be using UTF-8 encoding. * To use a String as a template use for instance new * ByteArrayInputStream("<template>".getBytes()). * @throws IOException */ public CustomLayout(InputStream templateStream) throws IOException { this(); initTemplateContentsFromInputStream(templateStream); } /** * Constructor for custom layout with given template name. Template file is * fetched from "<theme>/layouts/<templateName>". */ public CustomLayout(String template) { this(); setTemplateName(template); } protected void initTemplateContentsFromInputStream(InputStream templateStream) throws IOException { BufferedReader reader = new BufferedReader(new InputStreamReader(templateStream, UTF_8)); StringBuilder builder = new StringBuilder(BUFFER_SIZE); try { char[] cbuf = new char[BUFFER_SIZE]; int nRead; while ((nRead = reader.read(cbuf, 0, BUFFER_SIZE)) > 0) { builder.append(cbuf, 0, nRead); } } finally { reader.close(); } setTemplateContents(builder.toString()); } @Override protected CustomLayoutState getState() { return (CustomLayoutState) super.getState(); } @Override protected CustomLayoutState getState(boolean markAsDirty) { return (CustomLayoutState) super.getState(markAsDirty); } /** * Adds the component into this container to given location. If the location * is already populated, the old component is removed. * * @param c * the component to be added. * @param location * the location of the component. */ public void addComponent(Component c, String location) { final Component old = slots.get(location); if (old != null) { removeComponent(old); } slots.put(location, c); getState().childLocations.put(c, location); super.addComponent(c); } /** * Adds the component into this container. The component is added without * specifying the location (empty string is then used as location). Only one * component can be added to the default "" location and adding more * components into that location overwrites the old components. * * @param c * the component to be added. */ @Override public void addComponent(Component c) { this.addComponent(c, ""); } /** * Removes the component from this container. * * @param c * the component to be removed. */ @Override public void removeComponent(Component c) { if (c == null) { return; } slots.values().remove(c); getState().childLocations.remove(c); super.removeComponent(c); } /** * Removes the component from this container from given location. * * @param location * the Location identifier of the component. */ public void removeComponent(String location) { this.removeComponent(slots.get(location)); } /** * Gets the component container iterator for going trough all the components * in the container. * * @return the Iterator of the components inside the container. */ @Override public Iterator<Component> iterator() { return Collections.unmodifiableCollection(slots.values()).iterator(); } /** * Gets the number of contained components. Consistent with the iterator * returned by {@link #getComponentIterator()}. * * @return the number of contained components */ @Override public int getComponentCount() { return slots.values().size(); } /** * Gets the child-component by its location. * * @param location * the name of the location where the requested component * resides. * @return the Component in the given location or null if not found. */ public Component getComponent(String location) { return slots.get(location); } /* Documented in superclass */ @Override public void replaceComponent(Component oldComponent, Component newComponent) { // Gets the locations String oldLocation = null; String newLocation = null; for (final String location : slots.keySet()) { final Component component = slots.get(location); if (component == oldComponent) { oldLocation = location; } if (component == newComponent) { newLocation = location; } } if (oldLocation == null) { addComponent(newComponent); } else if (newLocation == null) { removeComponent(oldLocation); addComponent(newComponent, oldLocation); } else { slots.put(newLocation, oldComponent); slots.put(oldLocation, newComponent); getState().childLocations.put(newComponent, oldLocation); getState().childLocations.put(oldComponent, newLocation); } } /** Get the name of the template. */ public String getTemplateName() { return getState(false).templateName; } /** Get the contents of the template. */ public String getTemplateContents() { return getState(false).templateContents; } /** * Set the name of the template used to draw custom layout. * * With GWT-adapter, the template with name 'templatename' is loaded from * VAADIN/themes/themename/layouts/templatename.html. If the theme has not * been set (with Application.setTheme()), themename is 'default'. * * @param templateName */ public void setTemplateName(String templateName) { getState().templateName = templateName; getState().templateContents = null; } /** * Set the contents of the template used to draw the custom layout. * * Note: setTemplateContents can be applied only before CustomLayout * instance has been attached. * * @param templateContents */ public void setTemplateContents(String templateContents) { getState().templateContents = templateContents; getState().templateName = null; } @Override public void changeVariables(Object source, Map<String, Object> variables) { // Nothing to see here } @Override public void paintContent(PaintTarget target) throws PaintException { // Workaround to make the CommunicationManager read the template file // and send it to the client String templateName = getState(false).templateName; if (templateName != null && !templateName.isEmpty()) { Set<Object> usedResources = ((JsonPaintTarget) target).getUsedResources(); String resourceName = "layouts/" + templateName + ".html"; usedResources.add(resourceName); } } @Override public void readDesign(Element design, DesignContext designContext) { super.readDesign(design, designContext); for (Element child : design.children()) { Component childComponent = designContext.readDesign(child); if (child.hasAttr(":location")) { addComponent(childComponent, child.attr(":location")); } else { addComponent(childComponent); } } } @Override public void writeDesign(Element design, DesignContext designContext) { super.writeDesign(design, designContext); for (Entry<String, Component> slot : slots.entrySet()) { Element child = designContext.createElement(slot.getValue()); if (slots.size() > 1 || !"".equals(slot.getKey())) { child.attr(":location", slot.getKey()); } design.appendChild(child); } } }