simplesynchronousfilepagestore.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。

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.wicket.protocol.http.pagestore;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FilenameFilter;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

import org.apache.wicket.Application;
import org.apache.wicket.Page;
import org.apache.wicket.protocol.http.WebApplication;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Very simple page store that uses separate file for each serialized page instance. Also this store
 * doesn't use any worker threads.
 * <p>
 * This store is for demonstration purposes only and will perform badly in production.
 * 
 * @author Matej Knopp
 */
public class SimpleSynchronousFilePageStore extends AbstractPageStore
{
	private final File defaultWorkDir;
	private final String appName;

	/**
	 * Construct.
	 * 
	 * @param workDir
	 */
	public SimpleSynchronousFilePageStore(File workDir)
	{
		defaultWorkDir = workDir;
		defaultWorkDir.mkdirs();

		appName = Application.get().getApplicationKey();
	}

	/**
	 * Construct.
	 */
	public SimpleSynchronousFilePageStore()
	{
		this((File)((WebApplication)Application.get()).getServletContext().getAttribute(
				"javax.servlet.context.tempdir"));
	}

	private String getFileName(String pageMapName, int pageId)
	{
		return appName + "-pm-" + pageMapName + "-p-" + pageId;
	}

	// sort file by modification time
	private void sortFiles(File[] files)
	{
		Arrays.sort(files, new Comparator()
		{
			public int compare(Object arg0, Object arg1)
			{
				File f1 = (File)arg0;
				File f2 = (File)arg1;

				return f1.lastModified() < f2.lastModified() ? -1 : (f1.lastModified() == f2
						.lastModified() ? 0 : 1);
			}
		});
	}

	/**
	 * Returns the file for specified page. The specification might be incomplete (-1 set as
	 * versionNumber or ajaxVersionNumber). In that case, it search for the correct file. The search
	 * traverses the session folder which is inefficient and should not be used in production. It's
	 * good to manage/cache this information in page store implementations.
	 * 
	 * @param sessionDir
	 * @param pageMapName
	 * @param pageId
	 * @param versionNumber
	 * @param ajaxVersionNumber
	 * @return
	 */
	private File getPageFile(File sessionDir, String pageMapName, int pageId, int versionNumber,
			int ajaxVersionNumber)
	{
		final String fileNamePrefix = getFileName(pageMapName, pageId);
		if (versionNumber != -1 && ajaxVersionNumber != -1)
		{
			return new File(sessionDir, fileNamePrefix + "-v-" + versionNumber + "-a-" +
					ajaxVersionNumber);
		}
		else if (versionNumber == -1)
		{
			// if versionNumber is -1, we need the last touched (saved) file
			File[] files = sessionDir.listFiles(new FilenameFilter()
			{
				public boolean accept(File dir, String name)
				{
					return name.startsWith(fileNamePrefix);
				}
			});
			if (files == null || files.length == 0)
			{
				return null;
			}
			sortFiles(files);
			return files[files.length - 1];
		}
		else
		{
			// if versionNumber is specified and ajaxVersionNumber is -1, we
			// need page
			// with the highest ajax number
			final String prefixWithVersion = fileNamePrefix + "-v-" + versionNumber;
			// if versionNumber is -1, we need the last touched (saved) file
			File[] files = sessionDir.listFiles(new FilenameFilter()
			{
				public boolean accept(File dir, String name)
				{
					return name.startsWith(prefixWithVersion);
				}
			});
			if (files == null || files.length == 0)
			{
				return null;
			}
			// from the list of files, we need to pick one with highest ajax
			// version
			// (the last integer in file name)
			int lastAjaxVersion = -1;
			int indexWithBiggestAjaxVersion = -1;
			for (int i = 0; i < files.length; ++i)
			{
				File file = files[i];
				String ajaxVersionString = file.getName().substring(
						file.getName().lastIndexOf('-') + 1);
				int ajaxVersion = Integer.parseInt(ajaxVersionString);
				if (lastAjaxVersion < ajaxVersion)
				{
					lastAjaxVersion = ajaxVersion;
					indexWithBiggestAjaxVersion = i;
				}
			}

			return files[indexWithBiggestAjaxVersion];
		}
	}


	public void destroy()
	{
	}

	protected byte[] loadPageData(File workDir, String sessionId, String pageMapName, int pageId,
			int versionNumber, int ajaxVersionNumber)
	{
		File sessionDir = new File(workDir, sessionId);
		byte[] pageData = null;

		if (sessionDir.exists())
		{
			File pageFile = getPageFile(sessionDir, pageMapName, pageId, versionNumber,
					ajaxVersionNumber);
			if (pageFile.exists())
			{
				FileInputStream fis = null;
				try
				{
					fis = new FileInputStream(pageFile);
					int length = (int)pageFile.length();
					ByteBuffer bb = ByteBuffer.allocate(length);
					fis.getChannel().read(bb);
					if (bb.hasArray())
					{
						pageData = bb.array();
					}
					else
					{
						pageData = new byte[length];
						bb.get(pageData);
					}
				}
				catch (Exception e)
				{
					log.debug("Error loading page " + pageId + "," + versionNumber +
							" for the sessionid " + sessionId + " from disk", e);
				}
				finally
				{
					try
					{
						if (fis != null)
						{
							fis.close();
						}
					}
					catch (IOException ex)
					{
						// ignore
					}
				}
			}
		}
		return pageData;
	}

	public Page getPage(String sessionId, String pageMapName, int pageId, int versionNumber,
			int ajaxVersionNumber)
	{
		byte data[] = loadPageData(defaultWorkDir, sessionId, pageMapName, pageId, versionNumber,
				ajaxVersionNumber);
		if (data != null)
		{
			return deserializePage(data, versionNumber);
		}
		else
		{
			return null;
		}
	}

	public void pageAccessed(String sessionId, Page page)
	{
	}

	private void removeFiles(String sessionId, String pageMap, int id)
	{
		File sessionDir = new File(defaultWorkDir, sessionId);
		if (sessionDir.exists())
		{
			final String filepart;
			if (id != -1)
			{
				filepart = appName + "-pm-" + pageMap + "-p-" + id;
			}
			else
			{
				filepart = appName + "-pm-" + pageMap;
			}
			File[] listFiles = sessionDir.listFiles(new FilenameFilter()
			{
				public boolean accept(File dir, String name)
				{
					return name.startsWith(filepart);
				}
			});
			for (int i = 0; i < listFiles.length; i++)
			{
				listFiles[i].delete();
			}
		}

	}

	protected long savePageData(String sessionId, SerializedPage page)
	{
		File sessionDir = new File(defaultWorkDir, sessionId);
		sessionDir.mkdirs();

		File pageFile = getPageFile(sessionDir, page.getPageMapName(), page.getPageId(), page
				.getVersionNumber(), page.getAjaxVersionNumber());
		FileOutputStream fos = null;
		int length = 0;
		try
		{
			fos = new FileOutputStream(pageFile);
			ByteBuffer bb = ByteBuffer.wrap(page.getData());
			fos.getChannel().write(bb);
			length = page.getData().length;
		}
		catch (Exception e)
		{
			log.error("Error saving page " + pageFile.getAbsolutePath());
		}
		finally
		{
			try
			{
				if (fos != null)
				{
					fos.close();
				}
			}
			catch (IOException ex)
			{
				// ignore
			}
		}
		return length;
	}

	public void removePage(String sessionId, String pageMapName, int pageId)
	{
		removeFiles(sessionId, pageMapName, pageId);
	}

	public void storePage(String sessionId, Page page)
	{
		List/* SerializedPage */serialized = serializePage(page);

		for (Iterator i = serialized.iterator(); i.hasNext();)
		{
			SerializedPage serializedPage = (SerializedPage)i.next();
			savePageData(sessionId, serializedPage);
		}
	}

	private void removeSession(String sessionId)
	{
		File sessionDir = new File(defaultWorkDir, sessionId);
		if (sessionDir.exists())
		{
			File[] files = sessionDir.listFiles();
			if (files != null)
			{
				for (int i = 0; i < files.length; i++)
				{
					files[i].delete();
				}
			}
			if (!sessionDir.delete())
			{
				sessionDir.deleteOnExit();
			}
		}
	}

	public void unbind(String sessionId)
	{
		removeSession(sessionId);
	}

	public boolean containsPage(String sessionId, String pageMapName, int pageId, int pageVersion)
	{
		File sessionDir = new File(defaultWorkDir, sessionId);
		File pageFile = getPageFile(sessionDir, pageMapName, pageId, pageVersion, -1);
		return pageFile.exists();
	}

	private static final Logger log = LoggerFactory.getLogger(SimpleSynchronousFilePageStore.class);
}