diff -r 1612dbcec451 -r 639991d0808a java/cewolf-1.0/src/main/java/de/laures/cewolf/storage/AbstractSessionStorage.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/java/cewolf-1.0/src/main/java/de/laures/cewolf/storage/AbstractSessionStorage.java	Sat Feb 28 21:31:02 2009 +0100
@@ -0,0 +1,130 @@
+/* ================================================================
+ * Cewolf : Chart enabling Web Objects Framework
+ * ================================================================
+ *
+ * Project Info:  http://cewolf.sourceforge.net
+ * Project Lead:  Guido Laures (guido@laures.de);
+ *
+ * (C) Copyright 2002, by Guido Laures
+ *
+ * This library is free software; you can redistribute it and/or modify it under the terms
+ * of the GNU Lesser General Public License as published by the Free Software Foundation;
+ * either version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+ * without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with this
+ * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+package de.laures.cewolf.storage;
+
+import java.io.Serializable;
+
+import javax.servlet.ServletContext;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpSession;
+import javax.servlet.jsp.PageContext;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import de.laures.cewolf.CewolfException;
+import de.laures.cewolf.ChartImage;
+import de.laures.cewolf.Storage;
+import de.laures.cewolf.taglib.util.KeyGenerator;
+
+/**
+ * @author glaures
+ */
+public abstract class AbstractSessionStorage implements Storage
+{
+
+  private static final Log log = LogFactory.getLog(AbstractSessionStorage.class);
+
+  /**
+   * @see de.laures.cewolf.Storage#storeChartImage(ChartImage, ServletContext)
+   */
+  public String storeChartImage( ChartImage cid, PageContext pageContext ) throws CewolfException
+  {
+    if ( contains(cid, pageContext) )
+    {
+      return getKey(cid);
+    }
+    log.debug("storing chart " + cid);
+    final HttpSession session = pageContext.getSession();
+    //String key = getKey(cid);
+    return storeChartImage(cid, session);
+  }
+
+
+  /**
+   * @see de.laures.cewolf.Storage#getChartImage(String)
+   */
+  public ChartImage getChartImage( String id, HttpServletRequest request )
+  {
+    HttpSession session = request.getSession();
+    return (ChartImage) session.getAttribute(id);
+  }
+
+  public boolean contains( ChartImage cid, PageContext pageContext )
+  {
+    return pageContext.getSession().getAttribute(getKey(cid)) != null;
+  }
+
+  public final String getKey( ChartImage cid )
+  {
+    return String.valueOf(KeyGenerator.generateKey((Serializable) cid));
+  }
+
+  protected String storeChartImage( ChartImage cid, HttpSession session ) throws CewolfException
+  {
+    final String sessionKey = getKey(cid);
+    synchronized (session)
+    {
+      session.setAttribute(sessionKey, getCacheObject(cid));
+    }
+    return sessionKey;
+  }
+  
+	/**
+	 */
+	public String removeChartImage(String imgKey, HttpServletRequest request)
+			throws CewolfException {
+		final HttpSession session = request.getSession();
+		if (session == null)
+		{
+			return imgKey;
+		}
+		return removeChartImage(imgKey, session);		
+	}
+
+	/**
+	 * @param cid
+	 * @param session
+	 * @return
+	 * @throws CewolfException
+	 */
+	protected String removeChartImage(String cid, HttpSession session)
+			throws CewolfException {
+		synchronized (session) {
+			session.removeAttribute(cid);
+		}
+		return cid;
+	}
+
+  protected abstract Object getCacheObject( ChartImage cid ) throws CewolfException;
+
+  /**
+   * @see de.laures.cewolf.Storage#init(ServletContext)
+   */
+  public void init( ServletContext servletContext ) throws CewolfException
+  {
+  }
+  
+
+
+}
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