br.com.jhonsapp.util.jsf.cdi.ViewScopedContext Maven / Gradle / Ivy

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This project provides useful classes that facilitate the construction of new components web.
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package br.com.jhonsapp.util.jsf.cdi;

import java.lang.annotation.Annotation;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import javax.enterprise.context.ContextNotActiveException;
import javax.enterprise.context.spi.Context;
import javax.enterprise.context.spi.Contextual;
import javax.enterprise.context.spi.CreationalContext;
import javax.faces.bean.ViewScoped;
import javax.faces.component.UIViewRoot;
import javax.faces.context.FacesContext;
import javax.faces.event.PreDestroyViewMapEvent;
import javax.faces.event.SystemEvent;
import javax.faces.event.SystemEventListener;

/**
 * Copied from Seam Faces 3.1.0.
 *
 * @author Steve Taylor
 */

public class ViewScopedContext implements Context, SystemEventListener
{
	@Override
	public  T get(final Contextual component)
	{
		assertActive();

		if (!isJsfSubscribed)
		{
			FacesContext.getCurrentInstance().getApplication().subscribeToEvent(PreDestroyViewMapEvent.class, this);
			isJsfSubscribed = true;
		}

		T instance = (T) getComponentInstanceMap().get(component);

		return instance;
	}

	@Override
	public  T get(final Contextual component, final CreationalContext creationalContext)
	{
		assertActive();

		T instance = get(component);
		if (instance == null)
		{
			if (creationalContext != null)
			{
				Map, Object> componentInstanceMap = getComponentInstanceMap();
				Map, CreationalContext> creationalContextMap = getCreationalInstanceMap();

				synchronized (componentInstanceMap)
				{
					instance = (T) componentInstanceMap.get(component);
					if (instance == null)
					{
						instance = component.create(creationalContext);
						if (instance != null)
						{
							componentInstanceMap.put(component, instance);
							creationalContextMap.put(component, creationalContext);
						}
					}
				}
			}
		}

		return instance;
	}

	@Override
	public Class getScope()
	{
		return ViewScoped.class;
	}

	@Override
	public boolean isActive()
	{
		return getViewRoot() != null;
	}

	private void assertActive()
	{
		if (!isActive())
		{
			throw new ContextNotActiveException(
					"Seam context with scope annotation @ViewScoped is not active with respect to the current thread");
		}
	}

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

		return false;
	}

	/**
	 * We get PreDestroyViewMapEvent events from the JSF servlet and destroy our contextual instances. This should (theoretically!) also get fired if the webapp closes, so there should be no need to
	 * manually track all view scopes and destroy them at a shutdown.
	 *
	 * @see javax.faces.event.SystemEventListener#processEvent(javax.faces.event.SystemEvent)
	 */
	@Override
	public void processEvent(final SystemEvent event)
	{
		if (event instanceof PreDestroyViewMapEvent)
		{
			Map, Object> componentInstanceMap = getComponentInstanceMap();
			Map, CreationalContext> creationalContextMap = getCreationalInstanceMap();

			if (componentInstanceMap != null)
			{
				for (Map.Entry, Object> componentEntry : componentInstanceMap.entrySet())
				{
					/*
					 * No way to inform the compiler of type  information, so it has to be abandoned here :(
					 */
					Contextual contextual = componentEntry.getKey();
					Object instance = componentEntry.getValue();
					CreationalContext creational = creationalContextMap.get(contextual);

					contextual.destroy(instance, creational);
				}
			}
		}
	}

	protected UIViewRoot getViewRoot()
	{
		FacesContext context = FacesContext.getCurrentInstance();

		if (context != null)
		{
			return context.getViewRoot();
		}

		return null;
	}

	protected Map getViewMap()
	{
		UIViewRoot viewRoot = getViewRoot();

		if (viewRoot != null)
		{
			return viewRoot.getViewMap(true);
		}

		return null;
	}

	@SuppressWarnings("unchecked")
	private Map, Object> getComponentInstanceMap()
	{
		Map viewMap = getViewMap();
		Map, Object> map = (ConcurrentHashMap, Object>) viewMap.get(COMPONENT_MAP_NAME);

		if (map == null)
		{
			map = new ConcurrentHashMap, Object>();
			viewMap.put(COMPONENT_MAP_NAME, map);
		}

		return map;
	}

	@SuppressWarnings("unchecked")
	private Map, CreationalContext> getCreationalInstanceMap()
	{
		Map viewMap = getViewMap();
		Map, CreationalContext> map = (Map, CreationalContext>) viewMap.get(CREATIONAL_MAP_NAME);

		if (map == null)
		{
			map = new ConcurrentHashMap, CreationalContext>();
			viewMap.put(CREATIONAL_MAP_NAME, map);
		}

		return map;
	}

	private final static String COMPONENT_MAP_NAME = "org.jboss.seam.faces.viewscope.componentInstanceMap";

	private final static String CREATIONAL_MAP_NAME = "org.jboss.seam.faces.viewscope.creationalInstanceMap";

	private boolean isJsfSubscribed = false;
}