Java tutorial
/* * Copyright 2008 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.gdata.sample.hellogdata.client; import com.google.gwt.gdata.client.GData; import com.google.gwt.gdata.client.GDataSystemPackage; import com.google.gwt.gdata.client.gbase.GoogleBaseService; import com.google.gwt.gdata.client.gbase.SnippetsEntry; import com.google.gwt.gdata.client.gbase.SnippetsFeed; import com.google.gwt.gdata.client.gbase.SnippetsFeedCallback; import com.google.gwt.gdata.client.gbase.SnippetsQuery; import com.google.gwt.gdata.client.impl.CallErrorException; import com.google.gwt.user.client.ui.FlexTable; import com.google.gwt.user.client.ui.HTML; import com.google.gwt.user.client.ui.Label; /** * The following example demonstrates how to query snippets to find * jobs matching a set of parameters. */ public class GoogleBaseQuerySnippetsForJobsDemo extends GDataDemo { /** * This method is used by the main sample app to obtain * information on this sample and a sample instance. * * @return An instance of this demo. */ public static GDataDemoInfo init() { return new GDataDemoInfo() { @Override public GDataDemo createInstance() { return new GoogleBaseQuerySnippetsForJobsDemo(); } @Override public String getDescription() { return "<p>This sample uses a snippets query to find items " + "corresponding to jobs that match a set of criteria.</p>"; } @Override public String getName() { return "Base - Querying snippets for jobs"; } }; } private GoogleBaseService service; private FlexTable mainPanel; /** * Setup the Google Base service and create the main content panel. * Start the demo by querying Google Base snippets. */ public GoogleBaseQuerySnippetsForJobsDemo() { mainPanel = new FlexTable(); initWidget(mainPanel); if (!GData.isLoaded(GDataSystemPackage.GBASE)) { showStatus("Loading the GData Google-Base package...", false); GData.loadGDataApi(GDATA_API_KEY, new Runnable() { public void run() { startDemo(); } }, GDataSystemPackage.GBASE); } else { startDemo(); } } /** * Retrieves a snippets feed using a Query object. * In GData, feed URIs can contain query string parameters. The * GData query objects aid in building parameterized feed URIs. * Upon successfully receiving the snippets feed, the snippet entries * are displayed to the user via the showData method. * We set the BQ query string to search for jobs. * * @param itemsFeedUri The items feed uri. */ private void querySnippets(String itemsFeedUri) { showStatus("Loading snippets feed...", false); SnippetsQuery query = SnippetsQuery.newInstance(itemsFeedUri); query.setMaxResults(25); query.setBq("[employer: Google][job type:full-time][job function:Marketing]"); service.getSnippetsFeed(query, new SnippetsFeedCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while retrieving the snippets feed: " + caught.getMessage(), true); } public void onSuccess(SnippetsFeed result) { SnippetsEntry[] entries = result.getEntries(); if (entries.length == 0) { showStatus("No snippets matched the search criteria.", false); } else { showData(entries); } } }); } /** * Displays a set of Google Base snippet entries in a tabular * fashion with the help of a GWT FlexTable widget. The data fields * Name, Url and Value are displayed. * * @param entries The Google Base snippet entries to display. */ private void showData(SnippetsEntry[] snippets) { mainPanel.clear(); String[] labels = new String[] { "Name", "Url", "Value" }; mainPanel.insertRow(0); for (int i = 0; i < labels.length; i++) { mainPanel.addCell(0); mainPanel.setWidget(0, i, new Label(labels[i])); mainPanel.getFlexCellFormatter().setStyleName(0, i, "hm-tableheader"); } for (int i = 0; i < snippets.length; i++) { SnippetsEntry snippet = snippets[i]; int row = mainPanel.insertRow(i + 1); mainPanel.addCell(row); mainPanel.setWidget(row, 0, new Label(snippet.getTitle().getText())); mainPanel.addCell(row); if (snippet.getHtmlLink() == null) { mainPanel.setWidget(row, 1, new Label("Not available")); } else { String link = snippet.getHtmlLink().getHref(); mainPanel.setWidget(row, 1, new HTML("<a href=\"" + link + "\" target=\"_blank\">" + link + "</a>")); } mainPanel.addCell(row); mainPanel.setWidget(row, 2, new Label(snippet.getPublished().getValue().getDate().toString())); } } /** * Displays a status message to the user. * * @param message The message to display. * @param isError Indicates whether the status is an error status. */ private void showStatus(String message, boolean isError) { mainPanel.clear(); mainPanel.insertRow(0); mainPanel.addCell(0); Label msg = new Label(message); if (isError) { msg.setStylePrimaryName("hm-error"); } mainPanel.setWidget(0, 0, msg); } /** * Starts this demo. */ private void startDemo() { service = GoogleBaseService.newInstance("HelloGData_GoogleBase_QuerySnippetsForJobsDemo_v2.0"); querySnippets("http://www.google.com/base/feeds/snippets/"); } }