Clears the view map if the current ID does not match the new view ID.

ViewMapSystemEventListener.java

/*
 * Copyright 2014 John Yeary <jyeary@bluelotussoftware.com>.
 *
 * 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.
 */
/*
 * $Id: ViewMapSystemEventListener.java,v a954aef6f00c 2014/08/05 01:54:57 jyeary $
 */
package com.bluelotussoftware.jsf.listener;

import com.sun.faces.application.view.ViewScopeManager;
import java.util.Map;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.faces.event.AbortProcessingException;
import javax.faces.event.SystemEvent;
import javax.faces.event.SystemEventListener;

/**
 *
 * @author John Yeary <jyeary@bluelotussoftware.com>
 * @version 1.0
 */
public class ViewMapSystemEventListener implements SystemEventListener {

    private String currentId;

    @Override
    public void processEvent(SystemEvent event) throws AbortProcessingException {
        /*
         * 1. Get the source of the event and its view id.
         * 2. Check if the currentId is null, if so, set it to the source id.
         * 3. Check the currentId and the new id. 
         *     a. If they are the same, continue. We are on the same page.
         *     b. If they are different, clear the view map, and remove from Session map.
         */
        UIViewRoot uivr = (UIViewRoot) event.getSource();
        String id = uivr.getViewId();
        FacesContext fctx = FacesContext.getCurrentInstance();
        ViewScopeManager vsm = ViewScopeManager.getInstance(fctx);

        if (currentId == null) {
            currentId = id;
        }

        if (!currentId.equals(id)) {
            //Clear map and set currentId to new id.
            vsm.clear(fctx);
            String key = (String) uivr.getTransientStateHelper().getTransient(ViewScopeManager.VIEW_MAP_ID);
            uivr.getViewMap().clear();
            Map<String, Object> viewMaps = (Map<String, Object>) fctx.getExternalContext().getSessionMap().get(ViewScopeManager.ACTIVE_VIEW_MAPS);
            viewMaps.remove(key);
            currentId = id;
        }

    }

    @Override
    public boolean isListenerForSource(Object source) {
        return (source instanceof UIViewRoot);
    }

}