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 ru.ppsrk.gwt.client; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.LinkedList; import java.util.List; import ru.ppsrk.gwt.client.ComboCell.ComboItem; import ru.ppsrk.gwt.shared.SharedUtils; import com.google.gwt.cell.client.AbstractInputCell; import com.google.gwt.cell.client.Cell; import com.google.gwt.cell.client.SelectionCell; import com.google.gwt.cell.client.ValueUpdater; import com.google.gwt.core.client.GWT; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.NativeEvent; import com.google.gwt.dom.client.SelectElement; import com.google.gwt.safehtml.client.SafeHtmlTemplates; import com.google.gwt.safehtml.shared.SafeHtml; import com.google.gwt.safehtml.shared.SafeHtmlBuilder; /** * A {@link Cell} used to render a drop-down list. */ public class ComboCell extends AbstractInputCell<ComboItem, ComboItem> { public static class ComboList<T extends ComboItem> extends LinkedList<T> { /** * */ private static final long serialVersionUID = 4003094284338608670L; public ComboItem getItemByEnum(Enum<?> enoom) { return SharedUtils.getObjectFromCollectionById(this, Long.valueOf(enoom.ordinal())); } public ComboItem getItemById(Long id) { return SharedUtils.getObjectFromCollectionById(this, id); } public static ComboList<ComboItem> fromEnums(Enum<?>[] enums, String[] text) { ComboList<ComboItem> result = new ComboList<ComboItem>(); int i = 0; for (Enum<?> enumElement : enums) { result.add(new ComboItem(Long.valueOf(enumElement.ordinal()), text[i++])); } return result; } public static ComboList<ComboItem> fromHasListboxValues(List<? extends HasListboxValue> list) { ComboList<ComboItem> result = new ComboList<ComboItem>(); for (HasListboxValue element : list) { result.add(new ComboItem(element.getId(), element.getListboxValue())); } return result; } } @SuppressWarnings("serial") public static class ComboItem implements HasListboxValue { Long id; String listboxValue; public Long getId() { return id; } public void setId(Long id) { this.id = id; } /** * @param id * @param listboxValue */ public ComboItem(Long id, String listboxValue) { super(); this.id = id; this.listboxValue = listboxValue; } public String getListboxValue() { return listboxValue; } public void setListboxValue(String listboxValue) { this.listboxValue = listboxValue; } } interface Template extends SafeHtmlTemplates { @Template("<option value=\"{0}\">{1}</option>") SafeHtml deselected(Long id, String option); @Template("<option value=\"{0}\" selected=\"selected\">{1}</option>") SafeHtml selected(Long id, String option); } private static Template template; private HashMap<Long, Integer> indexForOption = new HashMap<Long, Integer>(); private final List<ComboItem> options; /** * Construct a new {@link SelectionCell} with the specified options. * * @param options * the options in the cell */ public ComboCell(List<? extends ComboItem> options) { super("change"); if (template == null) { template = GWT.create(Template.class); } this.options = new ArrayList<ComboItem>(options); refreshIndexes(); } public List<ComboItem> getOptions() { return options; } public void addOptionWithoutRefresh(ComboItem newOp) { options.add(newOp); } public void addOption(ComboItem newOp) { options.add(newOp); refreshIndexes(); } public void addOptions(Collection<? extends ComboItem> result) { options.addAll(result); refreshIndexes(); } public void removeOption(Long op) { options.remove(indexForOption.get(op).intValue()); refreshIndexes(); } public void clearOptions() { options.clear(); refreshIndexes(); } public void refreshIndexes() { int index = 0; for (ComboItem option : options) { indexForOption.put(option.getId(), index++); } } @Override public void onBrowserEvent(Context context, Element parent, ComboItem value, NativeEvent event, ValueUpdater<ComboItem> valueUpdater) { super.onBrowserEvent(context, parent, value, event, valueUpdater); String type = event.getType(); if ("change".equals(type)) { Object key = context.getKey(); SelectElement select = parent.getFirstChild().cast(); ComboItem newValue = options.get(select.getSelectedIndex()); setViewData(key, newValue); finishEditing(parent, newValue, key, valueUpdater); if (valueUpdater != null) { valueUpdater.update(newValue); } } } @Override public void render(Context context, ComboItem value, SafeHtmlBuilder sb) { // Get the view data. Object key = context.getKey(); ComboItem viewData = getViewData(key); if (viewData != null && viewData.equals(value)) { clearViewData(key); viewData = null; } int selectedIndex = getSelectedIndex(viewData == null ? value : viewData); sb.appendHtmlConstant("<select tabindex=\"-1\">"); int index = 0; for (ComboItem option : options) { if (index++ == selectedIndex) { sb.append(template.selected(option.getId(), option.getListboxValue())); } else { sb.append(template.deselected(option.getId(), option.getListboxValue())); } } sb.appendHtmlConstant("</select>"); } private int getSelectedIndex(ComboItem value) { if (value == null) { return -1; } Integer index = indexForOption.get(value.getId()); if (index == null) { return -1; } return index.intValue(); } }