Java tutorial
/* * Copyright 2010 Google Inc. * * 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.google.gwt.sample.showcase.client.content.cell; import com.google.gwt.cell.client.AbstractCell; import com.google.gwt.cell.client.Cell; import com.google.gwt.cell.client.CheckboxCell; import com.google.gwt.cell.client.CompositeCell; import com.google.gwt.cell.client.FieldUpdater; import com.google.gwt.cell.client.HasCell; import com.google.gwt.core.client.GWT; import com.google.gwt.dom.client.Element; import com.google.gwt.resources.client.ClientBundle; import com.google.gwt.resources.client.ImageResource; import com.google.gwt.safehtml.shared.SafeHtmlBuilder; import com.google.gwt.sample.showcase.client.content.cell.ContactDatabase.Category; import com.google.gwt.sample.showcase.client.content.cell.ContactDatabase.ContactInfo; import com.google.gwt.sample.showcase.client.content.cell.CwCellList.ContactCell; import com.google.gwt.user.client.ui.AbstractImagePrototype; import com.google.gwt.view.client.DefaultSelectionEventManager; import com.google.gwt.view.client.ListDataProvider; import com.google.gwt.view.client.SelectionModel; import com.google.gwt.view.client.TreeViewModel; import java.util.ArrayList; import java.util.List; import java.util.Map; import java.util.TreeMap; /** * The {@link TreeViewModel} used to organize contacts into a hierarchy. */ public class ContactTreeViewModel implements TreeViewModel { /** * The images used for this example. */ static interface Images extends ClientBundle { ImageResource contact(); ImageResource contactsGroup(); } /** * The cell used to render categories. */ private static class CategoryCell extends AbstractCell<Category> { /** * The html of the image used for contacts. */ private final String imageHtml; public CategoryCell(ImageResource image) { this.imageHtml = AbstractImagePrototype.create(image).getHTML(); } @Override public void render(Context context, Category value, SafeHtmlBuilder sb) { if (value != null) { sb.appendHtmlConstant(imageHtml).appendEscaped(" "); sb.appendEscaped(value.getDisplayName()); } } } /** * Tracks the number of contacts in a category that begin with the same * letter. */ private static class LetterCount implements Comparable<LetterCount> { private final Category category; private final char firstLetter; private int count; /** * Construct a new {@link LetterCount} for one contact. * * @param category the category * @param firstLetter the first letter of the contacts name */ public LetterCount(Category category, char firstLetter) { this.category = category; this.firstLetter = firstLetter; this.count = 1; } public int compareTo(LetterCount o) { return (o == null) ? -1 : (firstLetter - o.firstLetter); } @Override public boolean equals(Object o) { return compareTo((LetterCount) o) == 0; } @Override public int hashCode() { return firstLetter; } /** * Increment the count. */ public void increment() { count++; } } /** * A Cell used to render the LetterCount. */ private static class LetterCountCell extends AbstractCell<LetterCount> { @Override public void render(Context context, LetterCount value, SafeHtmlBuilder sb) { if (value != null) { sb.appendEscaped(value.firstLetter + " (" + value.count + ")"); } } } /** * The static images used in this model. */ private static Images images; private final ListDataProvider<Category> categoryDataProvider; private final Cell<ContactInfo> contactCell; private final DefaultSelectionEventManager<ContactInfo> selectionManager = DefaultSelectionEventManager .createCheckboxManager(); private final SelectionModel<ContactInfo> selectionModel; public ContactTreeViewModel(final SelectionModel<ContactInfo> selectionModel) { this.selectionModel = selectionModel; if (images == null) { images = GWT.create(Images.class); } // Create a data provider that provides categories. categoryDataProvider = new ListDataProvider<Category>(); List<Category> categoryList = categoryDataProvider.getList(); for (Category category : ContactDatabase.get().queryCategories()) { categoryList.add(category); } // Construct a composite cell for contacts that includes a checkbox. List<HasCell<ContactInfo, ?>> hasCells = new ArrayList<HasCell<ContactInfo, ?>>(); hasCells.add(new HasCell<ContactInfo, Boolean>() { private CheckboxCell cell = new CheckboxCell(true, false); public Cell<Boolean> getCell() { return cell; } public FieldUpdater<ContactInfo, Boolean> getFieldUpdater() { return null; } public Boolean getValue(ContactInfo object) { return selectionModel.isSelected(object); } }); hasCells.add(new HasCell<ContactInfo, ContactInfo>() { private ContactCell cell = new ContactCell(images.contact()); public Cell<ContactInfo> getCell() { return cell; } public FieldUpdater<ContactInfo, ContactInfo> getFieldUpdater() { return null; } public ContactInfo getValue(ContactInfo object) { return object; } }); contactCell = new CompositeCell<ContactInfo>(hasCells) { @Override public void render(Context context, ContactInfo value, SafeHtmlBuilder sb) { sb.appendHtmlConstant("<table><tbody><tr>"); super.render(context, value, sb); sb.appendHtmlConstant("</tr></tbody></table>"); } @Override protected Element getContainerElement(Element parent) { // Return the first TR element in the table. return parent.getFirstChildElement().getFirstChildElement().getFirstChildElement(); } @Override protected <X> void render(Context context, ContactInfo value, SafeHtmlBuilder sb, HasCell<ContactInfo, X> hasCell) { Cell<X> cell = hasCell.getCell(); sb.appendHtmlConstant("<td>"); cell.render(context, hasCell.getValue(value), sb); sb.appendHtmlConstant("</td>"); } }; } public <T> NodeInfo<?> getNodeInfo(T value) { if (value == null) { // Return top level categories. return new DefaultNodeInfo<Category>(categoryDataProvider, new CategoryCell(images.contactsGroup())); } else if (value instanceof Category) { // Return the first letters of each first name. Category category = (Category) value; List<ContactInfo> contacts = ContactDatabase.get().queryContactsByCategory(category); Map<Character, LetterCount> counts = new TreeMap<Character, LetterCount>(); for (ContactInfo contact : contacts) { Character first = contact.getFirstName().charAt(0); LetterCount count = counts.get(first); if (count == null) { count = new LetterCount(category, first); counts.put(first, count); } else { count.increment(); } } List<LetterCount> orderedCounts = new ArrayList<LetterCount>(counts.values()); return new DefaultNodeInfo<LetterCount>(new ListDataProvider<LetterCount>(orderedCounts), new LetterCountCell()); } else if (value instanceof LetterCount) { // Return the contacts with the specified character and first name. LetterCount count = (LetterCount) value; List<ContactInfo> contacts = ContactDatabase.get().queryContactsByCategoryAndFirstName(count.category, count.firstLetter + ""); ListDataProvider<ContactInfo> dataProvider = new ListDataProvider<ContactInfo>(contacts, ContactInfo.KEY_PROVIDER); return new DefaultNodeInfo<ContactInfo>(dataProvider, contactCell, selectionModel, selectionManager, null); } // Unhandled type. String type = value.getClass().getName(); throw new IllegalArgumentException("Unsupported object type: " + type); } public boolean isLeaf(Object value) { return value instanceof ContactInfo; } }