com.google.gwt.gdata.sample.hellogdata.client.MapsRetrieveMapsDemo.java Source code

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Here is the source code for com.google.gwt.gdata.sample.hellogdata.client.MapsRetrieveMapsDemo.java

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/*
 * 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.accounts.client.AuthSubStatus;
import com.google.gwt.accounts.client.User;
import com.google.gwt.gdata.client.GData;
import com.google.gwt.gdata.client.GDataSystemPackage;
import com.google.gwt.gdata.client.impl.CallErrorException;
import com.google.gwt.gdata.client.maps.MapEntry;
import com.google.gwt.gdata.client.maps.MapFeed;
import com.google.gwt.gdata.client.maps.MapFeedCallback;
import com.google.gwt.gdata.client.maps.MapsService;
import com.google.gwt.user.client.ui.FlexTable;
import com.google.gwt.user.client.ui.Label;

/**
 * The following example demonstrates how to retrieve a list of a user's maps.
 */
public class MapsRetrieveMapsDemo 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 MapsRetrieveMapsDemo();
            }

            @Override
            public String getDescription() {
                return "<p>This sample uses the maps feed to retrieve a list "
                        + "of all of the authenticated user's saved maps.</p>";
            }

            @Override
            public String getName() {
                return "Maps - Retrieving all maps";
            }
        };
    }

    private MapsService service;
    private FlexTable mainPanel;
    private final String scope = "http://maps.google.com/maps/feeds/maps/";

    /**
     * Setup the Google Maps service and create the main content panel.
     * If the user is not logged on to Google Maps display a message,
     * otherwise start the demo by retrieving the user's maps.
     */
    public MapsRetrieveMapsDemo() {
        mainPanel = new FlexTable();
        initWidget(mainPanel);
        if (!GData.isLoaded(GDataSystemPackage.MAPS)) {
            showStatus("Loading the GData Maps package...", false);
            GData.loadGDataApi(GDATA_API_KEY, new Runnable() {
                public void run() {
                    startDemo();
                }
            }, GDataSystemPackage.MAPS);
        } else {
            startDemo();
        }
    }

    /**
     * Retrieve the maps feed using the Maps service and
     * the maps feed uri. In GData all get, insert, update
     * and delete methods always receive a callback defining
     * success and failure handlers.
     * Here, the failure handler displays an error message while the
     * success handler calls showData to display the map entries.
     * 
     * @param mapsFeedUri The uri of the map feed
     */
    private void getMaps(String mapsFeedUri) {
        showStatus("Loading maps feed...", false);
        service.getMapFeed(mapsFeedUri, new MapFeedCallback() {
            public void onFailure(CallErrorException caught) {
                showStatus("An error occurred while retrieving the maps feed: " + caught.getMessage(), true);
            }

            public void onSuccess(MapFeed result) {
                MapEntry[] entries = result.getEntries();
                if (entries.length == 0) {
                    showStatus("You have no maps.", false);
                } else {
                    showData(entries);
                }
            }
        });
    }

    /**
    * Displays a set of Google Maps map entries in a tabular 
    * fashion with the help of a GWT FlexTable widget. The data fields 
    * Title and Updated are displayed.
    * 
    * @param entries The Google Maps map entries to display.
    */
    private void showData(MapEntry[] entries) {
        mainPanel.clear();
        String[] labels = new String[] { "Title", "Updated" };
        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 < entries.length; i++) {
            MapEntry entry = entries[i];
            int row = mainPanel.insertRow(i + 1);
            mainPanel.addCell(row);
            mainPanel.setWidget(row, 0, new Label(entry.getTitle().getText()));
            mainPanel.addCell(row);
            mainPanel.setWidget(row, 1, new Label(entry.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 = MapsService.newInstance("HelloGData_Maps_RetrieveMapsDemo_v2.0");
        if (User.getStatus(scope) == AuthSubStatus.LOGGED_IN) {
            getMaps("http://maps.google.com/maps/feeds/maps/default/full");
        } else {
            showStatus("You are not logged on to Google Maps.", true);
        }
    }
}