session.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

	/**
	 * Set the locale for this session.
	 * 
	 * @param locale
	 *            New locale
	 */
	public final void setLocale(final Locale locale)
	{
		if (locale == null)
		{
			throw new IllegalArgumentException("Parameter 'locale' must not be null");
		}
		this.locale = locale;
		dirty();
	}

	/**
	 * Sets the metadata for this session using the given key. If the metadata object is not of the
	 * correct type for the metadata key, an IllegalArgumentException will be thrown. For
	 * information on creating MetaDataKeys, see {@link MetaDataKey}.
	 * 
	 * @param key
	 *            The singleton key for the metadata
	 * @param object
	 *            The metadata object
	 * @throws IllegalArgumentException
	 * @see MetaDataKey
	 */
	public final void setMetaData(final MetaDataKey key, final Serializable object)
	{
		metaData = key.set(metaData, object);
	}

	/**
	 * Set the style (see {@link org.apache.wicket.Session}).
	 * 
	 * @param style
	 *            The style to set.
	 * @return the Session object
	 */
	public final Session setStyle(final String style)
	{
		this.style = style;
		dirty();
		return this;
	}

	/**
	 * THIS METHOD IS NOT PART OF THE WICKET PUBLIC API. DO NOT CALL IT.
	 * <p>
	 * The page will be 'touched' in the session. If it wasn't added yet to the pagemap, it will be
	 * added to the page map else it will set this page to the front.
	 * 
	 * If another page was removed because of this it will be cleaned up.
	 * 
	 * @param page
	 */
	public final void touch(Page page)
	{
		// store it in a list, so that the pages are really pushed
		// to the pagemap when the session does it update/detaches.
		// all the pages are then detached
		List lst = (List)touchedPages.get();
		if (lst == null)
		{
			lst = new ArrayList();
			touchedPages.set(lst);
			lst.add(page);
		}
		else if (!lst.contains(page))
		{
			lst.add(page);
		}
	}

	/**
	 * THIS METHOD IS NOT PART OF THE WICKET PUBLIC API. DO NOT CALL IT.
	 * <p>
	 * This method will remove a page that was previously added via touch()
	 * 
	 * @param page
	 */
	public final void untouch(Page page)
	{
		List lst = (List)touchedPages.get();
		if (lst != null)
		{
			lst.remove(page);
		}
	}

	/**
	 * @param visitor
	 *            The visitor to call at each Page in this PageMap.
	 */
	public final void visitPageMaps(final IPageMapVisitor visitor)
	{
		for (final Iterator iterator = getAttributeNames().iterator(); iterator.hasNext();)
		{
			final String attribute = (String)iterator.next();
			if (attribute.startsWith(pageMapAttributePrefix))
			{
				visitor.pageMap((IPageMap)getAttribute(attribute));
			}
		}
	}

	/**
	 * Registers a warning feedback message for this session
	 * 
	 * @param message
	 *            The feedback message
	 */
	public final void warn(final String message)
	{
		addFeedbackMessage(message, FeedbackMessage.WARNING);
	}

	/**
	 * Adds a feedback message to the list of messages
	 * 
	 * @param message
	 * @param level
	 * 
	 */
	private void addFeedbackMessage(String message, int level)
	{
		getFeedbackMessages().add(null, message, level);
		dirty();
	}

	/**
	 * @param pageMapName
	 *            Name of page map
	 * @return Session attribute holding page map
	 */
	private final String attributeForPageMapName(final String pageMapName)
	{
		return pageMapAttributePrefix + pageMapName;
	}

	/**
	 * Any attach logic for session subclasses. Called when a session is set for the thread.
	 */
	protected void attach()
	{
	}

	/**
	 * Any detach logic for session subclasses. This is called on the end of handling a request,
	 * when the RequestCycle is about to be detached from the current thread.
	 */
	protected void detach()
	{
		if (sessionInvalidated)
		{
			invalidateNow();
		}
	}

	/**
	 * Marks session state as dirty so that it will be flushed at the end of the request.
	 */
	public final void dirty()
	{
		dirty = true;
	}

	/**
	 * Gets the attribute value with the given name
	 * 
	 * @param name
	 *            The name of the attribute to store
	 * @return The value of the attribute
	 */
	protected final Object getAttribute(final String name)
	{
		if (!isTemporary())
		{
			RequestCycle cycle = RequestCycle.get();
			if (cycle != null)
			{
				return getSessionStore().getAttribute(cycle.getRequest(), name);
			}
		}
		else
		{
			if (temporarySessionAttributes != null)
			{
				return temporarySessionAttributes.get(name);
			}
		}
		return null;
	}

	/**
	 * @return List of attributes for this session
	 */
	protected final List getAttributeNames()
	{
		if (!isTemporary())
		{
			RequestCycle cycle = RequestCycle.get();
			if (cycle != null)
			{
				return getSessionStore().getAttributeNames(cycle.getRequest());
			}
		}
		else
		{
			if (temporarySessionAttributes != null)
			{
				return new ArrayList(temporarySessionAttributes.keySet());
			}
		}
		return Collections.EMPTY_LIST;
	}

	/**
	 * Gets the session store.
	 * 
	 * @return the session store
	 */
	protected ISessionStore getSessionStore()
	{
		if (sessionStore == null)
		{
			sessionStore = getApplication().getSessionStore();
		}
		return sessionStore;
	}

	/**
	 * Removes the attribute with the given name.
	 * 
	 * @param name
	 *            the name of the attribute to remove
	 */
	protected final void removeAttribute(String name)
	{
		if (!isTemporary())
		{
			RequestCycle cycle = RequestCycle.get();
			if (cycle != null)
			{
				getSessionStore().removeAttribute(cycle.getRequest(), name);
			}
		}
		else
		{
			if (temporarySessionAttributes != null)
			{
				temporarySessionAttributes.remove(name);
			}
		}
	}

	/**
	 * Adds or replaces the attribute with the given name and value.
	 * 
	 * @param name
	 *            The name of the attribute
	 * @param value
	 *            The value of the attribute
	 */
	protected final void setAttribute(String name, Object value)
	{
		if (!isTemporary())
		{
			RequestCycle cycle = RequestCycle.get();
			if (cycle == null)
			{
				throw new IllegalStateException(
					"Cannot set the attribute: no RequestCycle available.  If you get this error when using WicketTester.startPage(Page), make sure to call WicketTester.createRequestCycle() beforehand.");
			}

			ISessionStore store = getSessionStore();
			Request request = cycle.getRequest();

			// extra check on session binding event
			if (value == this)
			{
				Object current = store.getAttribute(request, name);
				if (current == null)
				{
					String id = store.getSessionId(request, false);
					if (id != null)
					{
						// this is a new instance. wherever it came from, bind
						// the session now
						store.bind(request, (Session)value);
					}
				}
			}

			// Set the actual attribute
			store.setAttribute(request, name, value);
		}
		else
		{
			// we don't have to synchronize, as it is impossible a temporary
			// session instance gets shared across threads
			if (temporarySessionAttributes == null)
			{
				temporarySessionAttributes = new HashMap(3);
			}
			temporarySessionAttributes.put(name, value);
		}
	}

	/**
	 * NOT TO BE CALLED BY FRAMEWORK USERS.
	 * 
	 * @deprecated obsolete method (was meant for internal book keeping really). Clients should
	 *             override {@link #detach()} instead.
	 */
	protected final void update()
	{
		throw new UnsupportedOperationException();
	}


	/**
	 * @param page
	 *            The page to add to dirty objects list
	 */
	void dirtyPage(final Page page)
	{
		List dirtyObjects = getDirtyObjectsList();
		if (!dirtyObjects.contains(page))
		{
			dirtyObjects.add(page);
		}
	}

	/**
	 * @param map
	 *            The page map to add to dirty objects list
	 */
	void dirtyPageMap(final IPageMap map)
	{
		if (!map.isDefault())
		{
			synchronized (usedPageMaps)
			{
				usedPageMaps.remove(map);
				usedPageMaps.addLast(map);
			}
		}
		List dirtyObjects = getDirtyObjectsList();
		if (!dirtyObjects.contains(map))
		{
			dirtyObjects.add(map);
		}
	}

	/**
	 * @return The current thread dirty objects list
	 */
	List getDirtyObjectsList()
	{
		List list = (List)dirtyObjects.get();
		if (list == null)
		{
			list = new ArrayList(4);
			dirtyObjects.set(list);
		}
		return list;
	}

	// TODO remove after deprecation release

	/**
	 * INTERNAL API. The request cycle when detached will call this.
	 * 
	 */
	final void requestDetached()
	{
		List touchedPages = (List)Session.touchedPages.get();
		Session.touchedPages.set(null);
		if (touchedPages != null)
		{
			for (int i = 0; i < touchedPages.size(); i++)
			{
				Page page = (Page)touchedPages.get(i);
				page.getPageMap().put(page);
			}
		}

		// If state is dirty
		if (dirty)
		{
			// State is no longer dirty
			dirty = false;

			// Set attribute.
			setAttribute(SESSION_ATTRIBUTE_NAME, this);
		}
		else
		{
			if (log.isDebugEnabled())
			{
				log.debug("update: Session not dirty.");
			}
		}

		List dirtyObjects = (List)Session.dirtyObjects.get();
		Session.dirtyObjects.set(null);

		Map tempMap = new HashMap();

		// Go through all dirty entries, replicating any dirty objects
		if (dirtyObjects != null)
		{
			for (final Iterator iterator = dirtyObjects.iterator(); iterator.hasNext();)
			{
				String attribute = null;
				Object object = iterator.next();
				if (object instanceof Page)
				{
					final Page page = (Page)object;
					if (page.isStateless())
					{
						// check, can it be that stateless pages where added to
						// the session?
						// and should be removed now?
						continue;
					}
					attribute = page.getPageMap().attributeForId(page.getNumericId());
					if (getAttribute(attribute) == null)
					{
						// page removed by another thread. don't add it again.
						continue;
					}
					object = page.getPageMapEntry();
				}
				else if (object instanceof IPageMap)
				{
					attribute = attributeForPageMapName(((IPageMap)object).getName());
				}

				// we might override some attributes, so we use a temporary map
				// and then just copy the last values to real sesssion
				tempMap.put(attribute, object);
			}
		}

		// in case we have dirty attributes, set them to session
		if (tempMap.isEmpty() == false)
		{
			for (Iterator i = tempMap.entrySet().iterator(); i.hasNext();)
			{
				Map.Entry entry = (Map.Entry)i.next();
				setAttribute((String)entry.getKey(), entry.getValue());
			}
		}

		if (pageMapsUsedInRequest != null)
		{
			synchronized (pageMapsUsedInRequest)
			{
				Thread t = Thread.currentThread();
				Iterator it = pageMapsUsedInRequest.entrySet().iterator();
				while (it.hasNext())
				{
					Entry entry = (Entry)it.next();
					if (((PageMapsUsedInRequestEntry)entry.getValue()).thread == t)
					{
						it.remove();
					}
				}
				pageMapsUsedInRequest.notifyAll();
			}
		}
	}

	private int pageIdCounter = 0;

	synchronized protected int nextPageId()
	{
		return pageIdCounter++;
	}
}