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.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.blogger.BlogEntry; import com.google.gwt.gdata.client.blogger.BlogFeed; import com.google.gwt.gdata.client.blogger.BlogFeedCallback; import com.google.gwt.gdata.client.blogger.BlogPostFeed; import com.google.gwt.gdata.client.blogger.BlogPostFeedCallback; import com.google.gwt.gdata.client.blogger.BloggerService; import com.google.gwt.gdata.client.blogger.PostEntry; import com.google.gwt.gdata.client.blogger.PostEntryCallback; 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 retrieve a specific blog * post entry. */ public class BloggerRetrieveSpecificBlogPostDemo 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 BloggerRetrieveSpecificBlogPostDemo(); } @Override public String getDescription() { return "<p>This sample returns a specific blog post by querying the " + "entry's URI with getBlogPostFeed().</p>"; } @Override public String getName() { return "Blogger - Retrieving a specific blog post"; } }; } private BloggerService service; private FlexTable mainPanel; private final String scope = "http://www.blogger.com/feeds/"; /** * Setup the Blogger service and create the main content panel. * If the user is not logged on to Blogger display a message, * otherwise start the demo by retrieving the user's blogs. */ public BloggerRetrieveSpecificBlogPostDemo() { mainPanel = new FlexTable(); initWidget(mainPanel); if (!GData.isLoaded(GDataSystemPackage.BLOGGER)) { showStatus("Loading the GData Blogger package...", false); GData.loadGDataApi(GDATA_API_KEY, new Runnable() { public void run() { startDemo(); } }, GDataSystemPackage.BLOGGER); } else { startDemo(); } } /** * Retrieve the Blogger blogs feed using the Blogger service and * the blogs 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 obtains the first Blog entry and * calls getPosts to retrieve the posts feed for that blog. * * @param blogsFeedUri The uri of the blogs feed */ private void getBlogs(String blogsFeedUri) { showStatus("Loading blog feed...", false); service.getBlogFeed(blogsFeedUri, new BlogFeedCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while retrieving the Blogger Blog " + "feed: " + caught.getMessage(), true); } public void onSuccess(BlogFeed result) { BlogEntry[] entries = result.getEntries(); if (entries.length == 0) { showStatus("You have no Blogger blogs.", false); } else { BlogEntry targetBlog = entries[0]; String postsFeedUri = targetBlog.getEntryPostLink().getHref(); getPosts(postsFeedUri); } } }); } /** * Retrieves a post entry by uri. On success, call * showData to display the post entry details. * * @param postEntryUri The uri of the post entry to retrieve */ private void getPost(String postEntryUri) { showStatus("Loading post entry...", false); service.getPostEntry(postEntryUri, new PostEntryCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while retrieving the Blogger Post " + "entry: " + caught.getMessage(), true); } public void onSuccess(PostEntry result) { showData(result); } }); } /** * Retrieve the Blogger posts feed using the Blogger service and * the posts feed uri for a given blog. * On success, call getPost on the first post entry. This will * retrieve the same entry that we already have, the purpose * is to exemplify retrieving a specific post entry directly. * If no posts are available, display a message. * * @param postsFeedUri The posts feed uri for a given blog */ private void getPosts(String postsFeedUri) { showStatus("Loading posts feed...", false); service.getBlogPostFeed(postsFeedUri, new BlogPostFeedCallback() { public void onFailure(CallErrorException caught) { showStatus("An error occurred while retrieving the Blogger Posts " + "feed: " + caught.getMessage(), true); } public void onSuccess(BlogPostFeed result) { PostEntry[] entries = result.getEntries(); if (entries.length == 0) { showStatus("No post entries found for the current blog.", false); } else { PostEntry targetPost = entries[0]; String postEntryUri = targetPost.getSelfLink().getHref(); getPost(postEntryUri); } } }); } /** * Displays a Blogger post entry in a tabular fashion with * the help of a GWT FlexTable widget. The data fields Title, * Author, Published and Contents are displayed. * * @param entry The Blogger post entry to display. */ private void showData(PostEntry entry) { mainPanel.clear(); mainPanel.insertRow(0); mainPanel.addCell(0); mainPanel.setWidget(0, 0, new HTML("<h2>" + entry.getTitle().getText() + "</h2>")); mainPanel.insertRow(1); mainPanel.addCell(1); mainPanel.setWidget(1, 0, new HTML("<i>By " + entry.getAuthors()[0].getName().getValue() + " on " + entry.getPublished().getValue().getDate().toString() + "</i>")); mainPanel.insertRow(2); mainPanel.addCell(2); mainPanel.setWidget(2, 0, new Label(entry.getContent().getText())); } /** * 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 = BloggerService.newInstance("HelloGData_Blogger_RetrieveSpecificBlogPostDemo_v2.0"); if (User.getStatus(scope) == AuthSubStatus.LOGGED_IN) { getBlogs("http://www.blogger.com/feeds/default/blogs"); } else { showStatus("You are not logged on to Blogger.", true); } } }