Java tutorial
/* * Copyright 2011 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.mobilewebapp.client; import com.google.gwt.activity.shared.ActivityManager; import com.google.gwt.core.client.GWT; import com.google.gwt.core.client.GWT.UncaughtExceptionHandler; import com.google.gwt.place.shared.Place; import com.google.gwt.place.shared.PlaceChangeEvent; import com.google.gwt.place.shared.PlaceController; import com.google.gwt.place.shared.PlaceHistoryHandler; import com.google.gwt.sample.gaerequest.client.ReloadOnAuthenticationFailure; import com.google.gwt.sample.mobilewebapp.client.activity.AppPlaceHistoryMapper; import com.google.gwt.sample.mobilewebapp.client.event.ActionEvent; import com.google.gwt.sample.mobilewebapp.client.event.ActionNames; import com.google.gwt.sample.mobilewebapp.client.event.ShowTaskEvent; import com.google.gwt.sample.mobilewebapp.presenter.task.TaskPlace; import com.google.gwt.sample.mobilewebapp.presenter.tasklist.TaskListPlace; import com.google.gwt.sample.mobilewebapp.shared.TaskProxy; import com.google.gwt.storage.client.Storage; import com.google.gwt.user.client.Window; import com.google.gwt.user.client.ui.HasWidgets; import com.google.web.bindery.event.shared.EventBus; import com.google.web.bindery.event.shared.UmbrellaException; import java.util.logging.Level; import java.util.logging.Logger; /** * The heart of the applicaiton, mainly concerned with bootstrapping. */ public class App { private static final String HISTORY_SAVE_KEY = "SAVEPLACE"; private static final Logger log = Logger.getLogger(App.class.getName()); private final Storage storage; /** * Where components of the app converse by posting and monitoring events. */ private final EventBus eventBus; /** * Owns the current {@link Place} in the app. A Place is the embodiment of any * bookmarkable state. */ private final PlaceController placeController; /** * The top of our UI. */ private final MobileWebAppShell shell; private final ActivityManager activityManager; private final AppPlaceHistoryMapper historyMapper; private final PlaceHistoryHandler historyHandler; private final ReloadOnAuthenticationFailure reloadOnAuthenticationFailure; public App(Storage storage, EventBus eventBus, PlaceController placeController, ActivityManager activityManager, AppPlaceHistoryMapper historyMapper, PlaceHistoryHandler historyHandler, ReloadOnAuthenticationFailure reloadOnAuthenticationFailure, MobileWebAppShell shell) { this.storage = storage; this.eventBus = eventBus; this.placeController = placeController; this.activityManager = activityManager; this.historyMapper = historyMapper; this.historyHandler = historyHandler; this.reloadOnAuthenticationFailure = reloadOnAuthenticationFailure; this.shell = shell; } /** * Given a parent view to show itself in, start this App. * * @param parentView where to show the app's widget */ public void run(HasWidgets.ForIsWidget parentView) { activityManager.setDisplay(shell); parentView.add(shell); ActionEvent.register(eventBus, ActionNames.ADD_TASK, new ActionEvent.Handler() { @Override public void onAction(ActionEvent event) { placeController.goTo(TaskPlace.getTaskCreatePlace()); } }); eventBus.addHandler(ShowTaskEvent.TYPE, new ShowTaskEvent.Handler() { @Override public void onShowTask(ShowTaskEvent event) { TaskProxy task = event.getTask(); placeController.goTo(TaskPlace.createTaskEditPlace(task.getId(), task)); } }); ActionEvent.register(eventBus, ActionNames.GO_HOME, new ActionEvent.Handler() { @Override public void onAction(ActionEvent event) { placeController.goTo(new TaskListPlace(false)); } }); ActionEvent.register(eventBus, ActionNames.TASK_SAVED, new ActionEvent.Handler() { @Override public void onAction(ActionEvent event) { placeController.goTo(new TaskListPlace(true)); } }); ActionEvent.register(eventBus, ActionNames.EDITING_CANCELED, new ActionEvent.Handler() { @Override public void onAction(ActionEvent event) { placeController.goTo(new TaskListPlace(false)); } }); GWT.setUncaughtExceptionHandler(new UncaughtExceptionHandler() { @Override public void onUncaughtException(Throwable e) { while (e instanceof UmbrellaException) { e = ((UmbrellaException) e).getCauses().iterator().next(); } String message = e.getMessage(); if (message == null) { message = e.toString(); } log.log(Level.SEVERE, "Uncaught exception", e); Window.alert("An unexpected error occurred: " + message); } }); // Check for authentication failures or mismatches reloadOnAuthenticationFailure.register(eventBus); initBrowserHistory(historyMapper, historyHandler, new TaskListPlace(true)); } /** * Initialize browser history / bookmarking. If LocalStorage is available, use * it to make the user's default location in the app the last one seen. */ private void initBrowserHistory(final AppPlaceHistoryMapper historyMapper, PlaceHistoryHandler historyHandler, TaskListPlace defaultPlace) { Place savedPlace = null; if (storage != null) { try { // wrap in try-catch in case stored value is invalid savedPlace = historyMapper.getPlace(storage.getItem(HISTORY_SAVE_KEY)); } catch (Throwable t) { // ignore error and use the default-default } } if (savedPlace == null) { savedPlace = defaultPlace; } historyHandler.register(placeController, eventBus, savedPlace); /* * Go to the place represented in the URL. This is what makes bookmarks * work. */ historyHandler.handleCurrentHistory(); /* * Monitor the eventbus for place changes and note them in LocalStorage for * the next launch. */ if (storage != null) { eventBus.addHandler(PlaceChangeEvent.TYPE, new PlaceChangeEvent.Handler() { public void onPlaceChange(PlaceChangeEvent event) { storage.setItem(HISTORY_SAVE_KEY, historyMapper.getToken(event.getNewPlace())); } }); } } }