secondlevelcachesessionstore.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。

		}

		private void writeObject(java.io.ObjectOutputStream s) throws IOException
		{

			s.defaultWriteObject();

			IPageStore store = getPageStore();

			// for IClusteredPageStore we just skip serializing the page, pagestore takes care of it
			if (sessionId != null && store instanceof IClusteredPageStore == false)
			{
				Object page = lastPage;
				if (store instanceof ISerializationAwarePageStore)
				{
					page = ((ISerializationAwarePageStore)store).prepareForSerialization(sessionId,
						page);
				}

				try
				{
					s.writeObject(page);
				}
				catch (Exception e)
				{
					throw new WicketRuntimeException("Failed to serialize " + page.toString(), e);
				}
			}
		}

		private void readObject(java.io.ObjectInputStream s) throws IOException,
			ClassNotFoundException
		{
			s.defaultReadObject();

			IPageStore store = getPageStore();

			if (sessionId != null && store instanceof IClusteredPageStore == false)
			{
				Object lastPage = s.readObject();
				if (store instanceof ISerializationAwarePageStore)
				{
					lastPage = ((ISerializationAwarePageStore)store).restoreAfterSerialization((Serializable)lastPage);
				}
				this.lastPage = lastPage;
			}
		}
	}

	/**
	 * version manager for this session store.
	 */
	private static final class SecondLevelCachePageVersionManager implements IPageVersionManager
	{
		private static final long serialVersionUID = 1L;

		private short currentVersionNumber;

		private short currentAjaxVersionNumber;

		private short lastAjaxVersionNumber;

		private final Page page;

		private transient boolean versionStarted;

		/**
		 * Construct.
		 * 
		 * @param page
		 */
		public SecondLevelCachePageVersionManager(Page page)
		{
			this.page = page;
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#beginVersion(boolean)
		 */
		public void beginVersion(boolean mergeVersion)
		{
			// this is an hack.. when object is read in. It must ignore the
			// first version bump.
			if (versionStarted)
			{
				return;
			}

			versionStarted = true;
			if (!mergeVersion)
			{
				// TODO: Skip existing versions! (Ask pagestore for last
				// version)
				currentVersionNumber++;
				lastAjaxVersionNumber = currentAjaxVersionNumber;
				currentAjaxVersionNumber = 0;
			}
			else
			{
				if (RequestCycle.get().getRequest() instanceof WebRequest &&
					((WebRequest)RequestCycle.get().getRequest()).isAjax())
				{
					currentAjaxVersionNumber++;
				}
			}
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#componentAdded(org.apache.wicket.Component)
		 */
		public void componentAdded(Component component)
		{
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#componentModelChanging(org.apache.wicket.Component)
		 */
		public void componentModelChanging(Component component)
		{
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#componentRemoved(org.apache.wicket.Component)
		 */
		public void componentRemoved(Component component)
		{
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#componentStateChanging(org.apache.wicket.version.undo.Change)
		 */
		public void componentStateChanging(Change change)
		{
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#endVersion(boolean)
		 */
		public void endVersion(boolean mergeVersion)
		{
			versionStarted = false;
			String sessionId = page.getSession().getId();
			if (sessionId != null)
			{
				page.getSession().touch(page);
			}
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#expireOldestVersion()
		 */
		public void expireOldestVersion()
		{
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#getAjaxVersionNumber()
		 */
		public int getAjaxVersionNumber()
		{
			return currentAjaxVersionNumber;
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#getCurrentVersionNumber()
		 */
		public int getCurrentVersionNumber()
		{
			return currentVersionNumber;
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#getVersion(int)
		 */
		public Page getVersion(int versionNumber)
		{
			if (currentVersionNumber == versionNumber)
			{
				return page;
			}
			return null;
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#getVersions()
		 */
		public int getVersions()
		{
			return 0;
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#ignoreVersionMerge()
		 */
		public void ignoreVersionMerge()
		{
			currentVersionNumber++;
			lastAjaxVersionNumber = currentAjaxVersionNumber;
			currentAjaxVersionNumber = 0;
		}

		/**
		 * @see org.apache.wicket.version.IPageVersionManager#rollbackPage(int)
		 */
		public Page rollbackPage(int numberOfVersions)
		{
			String sessionId = page.getSession().getId();
			if (sessionId != null)
			{
				int versionNumber = currentVersionNumber;
				int ajaxNumber = currentAjaxVersionNumber;
				if (versionStarted)
				{
					versionNumber--;
					ajaxNumber--;
				}

				IPageStore store = ((SecondLevelCacheSessionStore)Application.get()
					.getSessionStore()).getStore();
				// if the number of versions to rollback can be done inside the
				// current page version.
				if (ajaxNumber >= numberOfVersions)
				{
					return store.getPage(sessionId, page.getPageMapName(), page.getNumericId(),
						versionNumber, ajaxNumber - numberOfVersions);
				}
				else
				{
					// else go one page version down.
					versionNumber--;
					// then calculate the previous ajax version by looking at
					// the last ajax number of the previous version.
					ajaxNumber = lastAjaxVersionNumber - (numberOfVersions - ajaxNumber);
					if (ajaxNumber < 0)
					{
						// currently it is not supported to jump over 2
						// pages....
						log.error("trying to rollback to many versions, jumping over 2 page versions is not supported yet.");
						return null;
					}
					return store.getPage(sessionId, page.getPageMapName(), page.getNumericId(),
						versionNumber, ajaxNumber);
				}
			}

			return null;
		}

		private void readObject(java.io.ObjectInputStream s) throws IOException,
			ClassNotFoundException
		{
			s.defaultReadObject();
			// this is an hack.. when object is read in. It must ignore the
			// first version bump.

			// (matej_k) for now, I'm commenting it out. It causes serious
			// trouble with back
			// button, where new versions are not created as they should be
			// johan promised to look at it soon

			// versionStarted = true;
		}
	}

	static final ThreadLocal usedPages = new ThreadLocal();

	/**
	 * @return
	 */
	public static ThreadLocal getUsedPages()
	{
		return usedPages;
	}

	private final IPageStore pageStore;

	/**
	 * Construct.
	 * 
	 * @param application
	 *            The application for this store
	 * 
	 * @param pageStore
	 *            Page store for keeping page versions
	 */
	public SecondLevelCacheSessionStore(Application application, final IPageStore pageStore)
	{
		super(application);

		this.pageStore = pageStore;

		// turn automatic multi window support off by default, as we don't
		// really
		// need to be afraid to run out of history with this implementation.
		// note that the session store is created before Application#init is
		// called, so if users set this setting explicitly, it'll be overridden
		// (and that's exactly what we want: provide a better default, but not
		// forcing people to do away with this feature).
		Application.get().getPageSettings().setAutomaticMultiWindowSupport(false);
	}

	/**
	 * @see org.apache.wicket.protocol.http.HttpSessionStore#createPageMap(java.lang.String,
	 *      org.apache.wicket.Session)
	 */
	public IPageMap createPageMap(String name)
	{
		return new SecondLevelCachePageMap(Session.get().getId(), Application.get(), name);
	}

	/**
	 * @see org.apache.wicket.protocol.http.AbstractHttpSessionStore#onEndRequest(org.apache.wicket.Request)
	 */
	public void onEndRequest(Request request)
	{
		super.onEndRequest(request);
		usedPages.set(null);
	}

	/**
	 * @see org.apache.wicket.protocol.http.AbstractHttpSessionStore#destroy()
	 */
	public void destroy()
	{
		super.destroy();
		getStore().destroy();
	}

	/**
	 * @return The store to use
	 */
	public IPageStore getStore()
	{
		return pageStore;
	}

	/**
	 * @see org.apache.wicket.protocol.http.HttpSessionStore#newVersionManager(org.apache.wicket.Page)
	 */
	public IPageVersionManager newVersionManager(Page page)
	{
		return new SecondLevelCachePageVersionManager(page);
	}

	/**
	 * @see org.apache.wicket.session.ISessionStore#setAttribute(org.apache.wicket.Request,
	 *      java.lang.String, java.lang.Object)
	 */
	public void setAttribute(Request request, String name, Object value)
	{
		// ignore all pages, they are stored through the pagemap
		if (!(value instanceof Page))
		{
			super.setAttribute(request, name, value);
		}
	}

	/**
	 * @see org.apache.wicket.protocol.http.AbstractHttpSessionStore#onUnbind(java.lang.String)
	 */
	protected void onUnbind(String sessionId)
	{
		getStore().unbind(sessionId);
	}
}