com.googlecode.mgwt.mvp.client.history.MGWTPlaceHistoryHandler.java Source code

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Here is the source code for com.googlecode.mgwt.mvp.client.history.MGWTPlaceHistoryHandler.java

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/*
 * Copyright 2011 Daniel Kurka
 *
 * 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.googlecode.mgwt.mvp.client.history;

import java.util.logging.Logger;

import com.google.gwt.core.client.GWT;
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.DefaultHistorian;
import com.google.gwt.place.shared.PlaceHistoryHandler.Historian;
import com.google.gwt.place.shared.PlaceHistoryMapper;
import com.google.gwt.user.client.History;
import com.google.gwt.user.client.Window;
import com.google.web.bindery.event.shared.EventBus;
import com.google.web.bindery.event.shared.HandlerRegistration;

public class MGWTPlaceHistoryHandler {

    protected class DefaultHistoryHandler implements HistoryHandler {

        @Override
        public void replaceCurrentPlace(Place place) {
            String tokenForPlace = tokenForPlace(place);
            replaceToken(tokenForPlace);

        }

        @Override
        public void pushPlace(Place place) {
            String tokenForPlace = tokenForPlace(place);
            pushToken(tokenForPlace);

        }

        @Override
        public void goTo(Place place) {
            placeController.goTo(place);

        }

        @Override
        public void goTo(Place place, boolean ignore) {
            MGWTPlaceHistoryHandler.this.ignore = ignore;
            placeController.goTo(place);

        }

        @Override
        public Place getWhere() {
            return placeController.getWhere();
        }
    }

    protected final static Logger log = Logger.getLogger(MGWTPlaceHistoryHandler.class.getName());

    private EventBus eventBus;

    private final PlaceHistoryMapper placeHistoryMapper;

    private static final Historian GWT_historian = (Historian) GWT.create(DefaultHistorian.class);

    private static final Html5Historian historian = HTML5HistorianFactory.getHistorian();

    private PlaceController placeController;

    private boolean ignore;

    private final HistoryObserver historyObserver;

    private DefaultHistoryHandler defaultHistoryHandler;

    public MGWTPlaceHistoryHandler(PlaceHistoryMapper placeHistoryMapper, HistoryObserver historyObserver) {

        this.placeHistoryMapper = placeHistoryMapper;
        this.historyObserver = historyObserver;
        defaultHistoryHandler = new DefaultHistoryHandler();

    }

    public HandlerRegistration register(PlaceController placeController, EventBus eventBus, Place defaultPlace) {
        this.placeController = placeController;
        this.eventBus = eventBus;
        this.defaultPlace = defaultPlace;

        final HandlerRegistration bind = bind();

        final HandlerRegistration handlerRegistration = historyObserver.bind(eventBus, defaultHistoryHandler);

        return new HandlerRegistration() {
            public void removeHandler() {

                bind.removeHandler();
                handlerRegistration.removeHandler();
            }
        };
    }

    protected HandlerRegistration bind() {

        final HandlerRegistration popHandler = historian.addPopStateHandler(new PopStateHandler() {

            @Override
            public void onPopStateEvent(PopStateEvent event) {
                onPopStateEventOccured(event.getData());
            }
        });

        final HandlerRegistration placeChangeHandler = eventBus.addHandler(PlaceChangeEvent.TYPE,
                new PlaceChangeEvent.Handler() {

                    @Override
                    public void onPlaceChange(PlaceChangeEvent event) {
                        onPlaceChangeEvent(event);

                    }
                });

        return new HandlerRegistration() {
            public void removeHandler() {
                MGWTPlaceHistoryHandler.this.defaultPlace = Place.NOWHERE;
                MGWTPlaceHistoryHandler.this.placeController = null;
                popHandler.removeHandler();
                placeChangeHandler.removeHandler();
            }
        };

    }

    protected void onPlaceChangeEvent(PlaceChangeEvent event) {

        if (ignore) {
            ignore = false;
            return;
        }

        Place newPlace = event.getNewPlace();

        historyObserver.onPlaceChange(newPlace, defaultHistoryHandler);

        pushToken(tokenForPlace(newPlace));
    }

    protected void onPopStateEventOccured(String token) {

        Place place = getPlaceForToken(token);

        historyObserver.onHistoryChanged(place, defaultHistoryHandler);
        // TODO maybe handle differently?
        ignore = true;
        placeController.goTo(place);
    }

    protected void replaceToken(String token) {
        if (token.length() > 0) {
            historian.replaceState(token, Window.getTitle(), "#" + History.encodeHistoryToken(token));
        } else {
            historian.replaceState(token, Window.getTitle(), "");
        }
    }

    protected void pushToken(String token) {
        historian.pushState(token, Window.getTitle(), "#" + History.encodeHistoryToken(token));
    }

    public void handleCurrentHistory() {
        Place place = getPlaceForToken(GWT_historian.getToken());

        historyObserver.onAppStarted(place, defaultHistoryHandler);
        if (defaultPlace.equals(place)) {
            ignore = true;
        }

        placeController.goTo(place);
    }

    private Place defaultPlace = Place.NOWHERE;

    protected Place getPlaceForToken(String token) {

        Place newPlace = null;

        if ("".equals(token)) {
            newPlace = defaultPlace;
        }

        if (newPlace == null) {
            newPlace = placeHistoryMapper.getPlace(token);
        }

        if (newPlace == null) {
            log.warning("Unrecognized history token: " + token);
            newPlace = defaultPlace;
        }
        return newPlace;

    }

    private String tokenForPlace(Place newPlace) {

        if (defaultPlace.equals(newPlace)) {
            return "";
        }

        String token = placeHistoryMapper.getToken(newPlace);
        if (token != null) {
            return token;
        }

        log.warning("Place not mapped to a token: " + newPlace);
        return "";
    }
}