Fake session

   <source lang="java">

/*

* Copyright 2005 Joe Walker
*
* Licensed 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.
*/

import java.util.Collections; import java.util.Enumeration; import java.util.HashMap; import java.util.Map; import javax.servlet.ServletContext; import javax.servlet.http.HttpSession;

/**

* For the benefit of anyone that wants to create a fake HttpSession
* that doesn"t do anything other than not be null.
* @author Joe Walker [joe at getahead dot ltd dot uk]
*/

public class FakeHttpSession implements HttpSession {

   /**
    * Setup the creation time
    */
   public FakeHttpSession()
   {
       creationTime = System.currentTimeMillis();
   }
   /**
    * Setup the creation time
    * @param id The new session id
    */
   public FakeHttpSession(String id)
   {
       this.id = id;
       creationTime = System.currentTimeMillis();
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getCreationTime()
    */
   public long getCreationTime()
   {
       return creationTime;
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getId()
    */
   public String getId()
   {
       if (id == null)
       {
           System.out.println("Inventing data in FakeHttpSession.getId() to remain plausible.");
           id = "fake";
       }
       return id;
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getLastAccessedTime()
    */
   public long getLastAccessedTime()
   {
       return creationTime;
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getServletContext()
    */
   public ServletContext getServletContext()
   {
       return null;
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#setMaxInactiveInterval(int)
    */
   public void setMaxInactiveInterval(int maxInactiveInterval)
   {
       this.maxInactiveInterval = maxInactiveInterval;
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getMaxInactiveInterval()
    */
   public int getMaxInactiveInterval()
   {
       return maxInactiveInterval;
   }
   /**
    * @see javax.servlet.http.HttpSession#getSessionContext()
    * @deprecated
    */
   @SuppressWarnings({"UnnecessaryFullyQualifiedName"})
   @Deprecated
   public javax.servlet.http.HttpSessionContext getSessionContext()
   {
       return null;
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getAttribute(java.lang.String)
    */
   public Object getAttribute(String name)
   {
       return attributes.get(name);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getValue(java.lang.String)
    */
   @Deprecated
   public Object getValue(String name)
   {
       return attributes.get(name);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getAttributeNames()
    */
   public Enumeration<String> getAttributeNames()
   {
       return Collections.enumeration(attributes.keySet());
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#getValueNames()
    */
   @Deprecated
   public String[] getValueNames()
   {
       return attributes.keySet().toArray(new String[attributes.keySet().size()]);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#setAttribute(java.lang.String, java.lang.Object)
    */
   public void setAttribute(String name, Object value)
   {
       attributes.put(name, value);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#putValue(java.lang.String, java.lang.Object)
    */
   @Deprecated
   public void putValue(String name, Object value)
   {
       attributes.put(name, value);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#removeAttribute(java.lang.String)
    */
   public void removeAttribute(String name)
   {
       attributes.remove(name);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#removeValue(java.lang.String)
    */
   @Deprecated
   public void removeValue(String name)
   {
       attributes.remove(name);
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#invalidate()
    */
   public void invalidate()
   {
   }
   /* (non-Javadoc)
    * @see javax.servlet.http.HttpSession#isNew()
    */
   public boolean isNew()
   {
       return true;
   }
   /**
    * The session id
    */
   private String id = null;
   /**
    * The list of attributes
    */
   private Map<String, Object> attributes = new HashMap<String, Object>();
   /**
    * When were we created
    */
   private long creationTime;
   /**
    * How long before we timeout?
    */
   private int maxInactiveInterval = 30 * 60 * 1000;

}

 </source>

Map adaptor for HttpSession objects

   <source lang="java">

/*

* Copyright 2004-2005 Malcolm A. Edgar
*
* Licensed 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.
*/

import java.util.Collection; import java.util.Collections; import java.util.Enumeration; import java.util.HashSet; import java.util.Iterator; import java.util.Map; import java.util.Set; import javax.servlet.http.HttpSession; /**

* Provides a Map adaptor for HttpSession objects. A SessionMap instance is
* available in each Velocity page using the name "session".
* <p/>
* For example suppose we have a User object in the session with the
* attribute name "user" when a user is logged on.  We can display the users
* name in the page when the are logged onto the system.
*

*

 * <span class="red">#if</span> (<span class="blue">$session</span>.user)
 *   <span class="blue">$session</span>.user.fullname you are logged on.
 * <span class="red">#else</span>
 *   You are not logged on.
 * <span class="red">#end</span>

*
* The ClickServlet adds a SessionMap instance to the Velocity Context before
* it is merged with the page template.
* <p/>
* The SessionMap supports {@link FlashAttribute} which when accessed via
* {@link #get(Object)} are removed from the session.
*
* @author Malcolm.Edgar
*/

public class SessionMap implements Map {

   /** The internal session attribute. */
   protected HttpSession session;
   /**
    * Create a HttpSession Map adaptor.
    *
    * @param value the http session
    */
   public SessionMap(HttpSession value) {
       session = value;
   }
   /**
    * @see java.util.Map#size()
    */
   public int size() {
       if (session != null) {
           int size = 0;
           Enumeration enumeration = session.getAttributeNames();
           while (enumeration.hasMoreElements()) {
               enumeration.nextElement();
               size++;
           }
           return size;
       } else {
           return 0;
       }
   }
   /**
    * @see java.util.Map#isEmpty()
    */
   public boolean isEmpty() {
       return size() == 0;
   }
   /**
    * @see java.util.Map#containsKey(Object)
    */
   public boolean containsKey(Object key) {
       if (session != null && key != null) {
           return session.getAttribute(key.toString()) != null;
       } else {
           return false;
       }
   }
   /**
    * This method is not supported and will throw
    * UnsupportedOperationException if invoked.
    *
    * @see java.util.Map#containsValue(Object)
    */
   public boolean containsValue(Object value) {
       throw new UnsupportedOperationException();
   }
   /**
    * If the stored object is a FlashObject this method will return the
    * FlashObject value and then remove it from the session.
    *
    * @see java.util.Map#get(Object)
    */
   public Object get(Object key) {
       if (session != null && key != null) {
           Object object = session.getAttribute(key.toString());
           if (object instanceof FlashAttribute) {
               FlashAttribute flashObject = (FlashAttribute) object;
               object = flashObject.getValue();
               session.removeAttribute(key.toString());
           }
           return object;
       } else {
           return null;
       }
   }
   /**
    * @see java.util.Map#put(Object, Object)
    */
   public Object put(Object key, Object value) {
       if (session != null && key != null) {
           Object out = session.getAttribute(key.toString());
           session.setAttribute(key.toString(), value);
           return out;
       } else {
           return null;
       }
   }
   /**
    * @see java.util.Map#remove(Object)
    */
   public Object remove(Object key) {
       if (session != null && key != null) {
           Object out = session.getAttribute(key.toString());
           session.removeAttribute(key.toString());
           return out;
       } else {
           return null;
       }
   }
   /**
    * @see java.util.Map#putAll(Map)
    */
   public void putAll(Map map) {
       if (session != null && map != null) {
           for (Iterator i = map.entrySet().iterator(); i.hasNext();) {
               Map.Entry entry = (Map.Entry) i.next();
               String key = entry.getKey().toString();
               Object value = entry.getValue();
               session.setAttribute(key, value);
           }
       }
   }
   /**
    * @see java.util.Map#clear()
    */
   public void clear() {
       if (session != null) {
           Enumeration enumeration = session.getAttributeNames();
           while (enumeration.hasMoreElements()) {
               String name = enumeration.nextElement().toString();
               session.removeAttribute(name);
           }
       }
   }
   /**
    * @see java.util.Map#keySet()
    */
   public Set keySet() {
       if (session != null) {
           Set keySet = new HashSet();
           Enumeration enumeration = session.getAttributeNames();
           while (enumeration.hasMoreElements()) {
               keySet.add(enumeration.nextElement());
           }
           return keySet;
       } else {
           return Collections.EMPTY_SET;
       }
   }
   /**
    * This method is not supported and will throw
    * UnsupportedOperationException if invoked.
    *
    * @see java.util.Map#values()
    */
   public Collection values() {
       throw new UnsupportedOperationException();
   }
   /**
    * @see java.util.Map#entrySet()
    */
   public Set entrySet() {
       if (session != null) {
           Set entrySet = new HashSet();
           Enumeration enumeration = session.getAttributeNames();
           while (enumeration.hasMoreElements()) {
               String name = enumeration.nextElement().toString();
               Object value = session.getAttribute(name);
               entrySet.add(value);
           }
           return entrySet;
       } else {
           return Collections.EMPTY_SET;
       }
   }

}

 </source>

Servlet: session attribute listener

   <source lang="java">

import javax.servlet.http.HttpSession; import javax.servlet.http.HttpSessionAttributeListener; import javax.servlet.http.HttpSessionBindingEvent; public class SessionAttribListen implements HttpSessionAttributeListener {

 /** Creates new SessionAttribListen */
 public SessionAttribListen() {
   System.out.println(getClass().getName());
 }
 public void attributeAdded(HttpSessionBindingEvent se) {
   HttpSession session = se.getSession();
   String id = session.getId();
   String name = se.getName();
   String value = (String) se.getValue();
   String source = se.getSource().getClass().getName();
   String message = new StringBuffer("Attribute bound to session in ")
       .append(source).append("\nThe attribute name: ").append(name)
       .append("\n").append("The attribute value:").append(value)
       .append("\n").append("The session ID: ").append(id).toString();
   System.out.println(message);
 }
 public void attributeRemoved(HttpSessionBindingEvent se) {
   HttpSession session = se.getSession();
   String id = session.getId();
   String name = se.getName();
   if (name == null)
     name = "Unknown";
   String value = (String) se.getValue();
   String source = se.getSource().getClass().getName();
   String message = new StringBuffer("Attribute unbound from session in ")
       .append(source).append("\nThe attribute name: ").append(name)
       .append("\n").append("The attribute value: ").append(value)
       .append("\n").append("The session ID: ").append(id).toString();
   System.out.println(message);
 }
 public void attributeReplaced(HttpSessionBindingEvent se) {
   String source = se.getSource().getClass().getName();
   String message = new StringBuffer("Attribute replaced in session  ")
       .append(source).toString();
   System.out.println(message);
 }

}

 </source>

Servlet: Session bind listener

   <source lang="java">

import java.util.HashMap; import java.util.Map; import javax.servlet.http.HttpSession; import javax.servlet.http.HttpSessionBindingEvent; import javax.servlet.http.HttpSessionBindingListener; public class SessionBindListen implements HttpSessionBindingListener {

 private Map info;
 /** Creates new SessionBindListen */
 public SessionBindListen() {
   //zero-arg constructor
   info = new HashMap();
 }
 public void valueBound(HttpSessionBindingEvent be) {
   HttpSession session = be.getSession();
   String id = session.getId();
   String name = be.getName();
   Object value = be.getValue();
   String source = be.getSource().getClass().getName();
   String message = new StringBuffer("Attribute bound to session in ")
       .append(source).append("\nThe attribute name: ").append(name)
       .append("\n").append("The attribute value: ").append(value)
       .append("\n").append("The session id: ").append(id).toString();
   System.out.println(message);
 }
 public void valueUnbound(HttpSessionBindingEvent be) {
   HttpSession session = be.getSession();
   String id = session.getId();
   String name = be.getName();
   if (name == null)
     name = "Unknown";
   String source = be.getSource().getClass().getName();
   String message = new StringBuffer("Attribute unbound from session in ")
       .append(source).append("\nThe attribute name: ").append(name)
       .append("\n").append("The session id: ").append(id).toString();
   //clear Map; send message
   info.clear();
   System.out.println(message + "\nThe size of the HashMap is: "
       + info.size());
 }
 public void addInfo(String name, String email) {
   info.put(email, name);
 }

}

 </source>

Servlet: Session display

   <source lang="java">

import java.text.DateFormat; import java.util.Date; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class SessionDisplay extends HttpServlet {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, java.io.IOException {
   response.setContentType("text/html");
   java.io.PrintWriter out = response.getWriter();
   HttpSession session = request.getSession();
   Date creationTime = new Date(session.getCreationTime());
   Date lastAccessed = new Date(session.getLastAccessedTime());
   Date now = new Date();
   DateFormat formatter = DateFormat.getDateTimeInstance(
       DateFormat.MEDIUM, DateFormat.MEDIUM);
   out.println("<html>");
   out.println("<head>");
   out.println("<title>Displaying the Session Creation and Last-Accessed Time</title>");
   out.println("</head>");
   out.println("<body>");

out.println("

Session Creation and Last-Accessed Time

");

   out.println("The time and date now is: " + formatter.format(now)
       + "

");
   out.println("The session creation time: HttpSession.getCreationTime( ): "
           + formatter.format(creationTime) + "

");
   out.println("The last time the session was accessed: HttpSession.getLastAccessedTime( ): "
           + formatter.format(lastAccessed));
   out.println("</body>");
   out.println("</html>");
 }

}

 </source>

Servlet Session Example

   <source lang="java">

/*

* Copyright 2004 The Apache Software Foundation
*
* Licensed 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.
*/

/* $Id: SessionExample.java,v 1.4 2004/03/18 16:40:33 jfarcand Exp $

*
*/

import java.io.*; import java.text.*; import java.util.*; import javax.servlet.*; import javax.servlet.http.*; /**

* Example servlet showing request headers
* 
* @author James Duncan Davidson <duncan@eng.sun.ru>
*/

public class SessionExample extends HttpServlet {

 ResourceBundle rb = ResourceBundle.getBundle("LocalStrings");
 public void doGet(HttpServletRequest request, HttpServletResponse response)
     throws IOException, ServletException {
   response.setContentType("text/html");
   PrintWriter out = response.getWriter();
   out.println("<html>");
   out.println("<body bgcolor=\"white\">");
   out.println("<head>");
   String title = rb.getString("sessions.title");
   out.println("<title>" + title + "</title>");
   out.println("</head>");
   out.println("<body>");
   // img stuff not req"d for source code html showing
   // relative links everywhere!
   // XXX
   // making these absolute till we work out the
   // addition of a PathInfo issue
   out.println("");
   out.println("</body>");
   out.println("</html>");
   out.println("</body>");
   out.println("</html>");
 }
 public void doPost(HttpServletRequest request, HttpServletResponse response)
     throws IOException, ServletException {
   doGet(request, response);
 }

} /*

* Copyright 2004 The Apache Software Foundation
* 
* Licensed 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.
*/

/**

* HTML filter utility.
* 
* @author Craig R. McClanahan
* @author Tim Tye
* @version $Revision: 1.2 $ $Date: 2004/03/18 16:40:34 $
*/

final class HTMLFilter {

 /**
  * Filter the specified message string for characters that are sensitive in
  * HTML. This avoids potential attacks caused by including JavaScript codes
  * in the request URL that is often reported in error messages.
  * 
  * @param message
  *            The message string to be filtered
  */
 public static String filter(String message) {
   if (message == null)
     return (null);
   char content[] = new char[message.length()];
   message.getChars(0, message.length(), content, 0);
   StringBuffer result = new StringBuffer(content.length + 50);
   for (int i = 0; i < content.length; i++) {
     switch (content[i]) {
     case "<":
       result.append("<");
       break;
     case ">":
       result.append(">");
       break;
     case "&":
       result.append("&");
       break;
     case """:
       result.append(""");
       break;
     default:
       result.append(content[i]);
     }
   }
   return (result.toString());
 }

}

 </source>

Servlet : session filter

   <source lang="java">

import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; public class SessionFilter implements Filter {

 private FilterConfig config;
 /** Creates new SessionFilter */
 public SessionFilter() {
 }
 public void init(FilterConfig filterConfig) throws ServletException {
   System.out.println("Instance created of " + getClass().getName());
   this.config = filterConfig;
 }
 public void doFilter(ServletRequest request, ServletResponse response,
     FilterChain chain) throws java.io.IOException, ServletException {
   HttpSession session = ((HttpServletRequest) request).getSession();
   ServletContext context = config.getServletContext();
   /*
    * use the ServletContext.log method to log filter messages
    */
   context.log("doFilter called in: " + config.getFilterName() + " on "
       + (new java.util.Date()));
   // log the session ID
   context.log("session ID: " + session.getId());
   // Find out whether the logged-in session attribute is set
   String logged = (String) session.getAttribute("logged-in");
   if (logged == null)
     session.setAttribute("logged-in", "no");
   //log a message about the log-in status
   context.log("log-in status: "
       + (String) session.getAttribute("logged-in"));
   context.log("");
   chain.doFilter(request, response);
 }
 public void destroy() {
   /*
    * called before the Filter instance is removed from service by the web
    * container
    */
 }

}

 </source>

Servlet: session listener

   <source lang="java">

import java.util.Date; import javax.servlet.http.HttpSession; import javax.servlet.http.HttpSessionEvent; import javax.servlet.http.HttpSessionListener; public class SessionListen implements HttpSessionListener {

 private int sessionCount;
 public SessionListen() {
   this.sessionCount = 0;
 }
 public void sessionCreated(HttpSessionEvent se) {
   HttpSession session = se.getSession();
   session.setMaxInactiveInterval(60);
   synchronized (this) {
     sessionCount++;
   }
   String id = session.getId();
   Date now = new Date();
   String message = new StringBuffer("New Session created on ").append(
       now.toString()).append("\nID: ").append(id).append("\n")
       .append("There are now ").append("" + sessionCount).append(
           " live sessions in the application.").toString();
   System.out.println(message);
 }
 public void sessionDestroyed(HttpSessionEvent se) {
   HttpSession session = se.getSession();
   String id = session.getId();
   synchronized (this) {
     --sessionCount;
   }
   String message = new StringBuffer("Session destroyed"
       + "\nValue of destroyed session ID is").append("" + id).append(
       "\n").append("There are now ").append("" + sessionCount)
       .append(" live sessions in the application.").toString();
   System.out.println(message);
 }

}

 </source>

Servlet: simple session

   <source lang="java">

import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class SimpleSession extends HttpServlet {

 public void doGet(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, java.io.IOException {
   response.setContentType("text/html");
   java.io.PrintWriter out = response.getWriter();
   HttpSession session = request.getSession();
   out.println("<html>");
   out.println("<head>");
   out.println("<title>Simple Session Tracker</title>");
   out.println("</head>");
   out.println("<body>");

out.println("

Session Info

");

   out.println("session Id: " + session.getId() + "

");
   out.println("The SESSION TIMEOUT period is "
       + session.getMaxInactiveInterval() + " seconds.

");
   out.println("Now changing it to 20 minutes.

");
   session.setMaxInactiveInterval(20 * 60);
   out.println("The SESSION TIMEOUT period is now "
       + session.getMaxInactiveInterval() + " seconds.");
   out.println("</body>");
   out.println("</html>");
 }
 /**
  * Handles the HTTP POST method.
  * 
  * @param request
  *            servlet request
  * @param response
  *            servlet response
  */
 protected void doPost(HttpServletRequest request,
     HttpServletResponse response) throws ServletException,
     java.io.IOException {
   doGet(request, response);
 }

}

 </source>

Session Events: implements HttpSessionBindingListener

   <source lang="java">

import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletContext; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; import javax.servlet.http.HttpSessionBindingEvent; import javax.servlet.http.HttpSessionBindingListener; public class Binder extends HttpServlet {

 public void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException,
     IOException {
   resp.setContentType("text/html");
   PrintWriter out = resp.getWriter();
   HttpSession session = req.getSession(true);
   SessionObject o = new SessionObject(getServletContext());
   session.setAttribute("Binder.object", o);
   out.println("<html>");
   out.println("<head>");
   out.println("<title>Session Binder</title>");
   out.println("</head>");
   out.println("<body>");
   out.println("Object bound to session " + session.getId());
   out.println("</body>");
   out.println("</html>");
   out.flush();
 }

} class SessionObject implements HttpSessionBindingListener {

 ServletContext context;
 public SessionObject(ServletContext context) {
   this.context = context;
 }
 public void valueBound(HttpSessionBindingEvent event) {
   context.log("" + (new java.util.Date()) + " Binding " + event.getName() + " to session "
       + event.getSession().getId());
 }
 public void valueUnbound(HttpSessionBindingEvent event) {
   context.log("" + (new java.util.Date()) + " Unbinding " + event.getName() + " from session "
       + event.getSession().getId());
 }

}

 </source>

Session Expiration Filter

   <source lang="java">

/*

************************************************************************************
* Copyright (C) 2008-2009 Openbravo S.L.
* Licensed under the Apache Software License version 2.0
* 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.
************************************************************************************
*/

import java.io.IOException; import java.util.Date; import javax.servlet.Filter; import javax.servlet.FilterChain; import javax.servlet.FilterConfig; import javax.servlet.ServletException; import javax.servlet.ServletRequest; import javax.servlet.ServletResponse; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; public class SessionExpirationFilter implements Filter {

 public void init(FilterConfig config) {
 }
 public void doFilter(ServletRequest req, ServletResponse resp, FilterChain chain)
     throws IOException, ServletException {
   HttpServletRequest hReq = (HttpServletRequest) req;
   HttpSession session = hReq.getSession(false);
   if (null != session) {
     Date expirationDate = (Date) session.getAttribute("expirationDate");
     if (expirationDate == null)
       expirationDate = new Date(System.currentTimeMillis() + 1000000); // only
     // for
     // make
     // false
     // "expirationDate.before(new Date())"
     // in
     // the
     // first
     // execution
     if (expirationDate.before(new Date())) {
       session.invalidate();
       session = null;
     } else {
       // ignore requests marked as both ajaxCall and ignoreForSessionTimeout
       String isAjaxCall = hReq.getParameter("IsAjaxCall");
       String ignoreForSessionTimeout = hReq.getParameter("ignoreForSessionTimeout");
       boolean ignoreForTimeout = "1".equals(isAjaxCall) && ("1".equals(ignoreForSessionTimeout));
       if (ignoreForTimeout) {
         // Do nothing; don"t update the session timestamp
       } else {
         session.setAttribute("expirationDate", new Date(System.currentTimeMillis()
             + session.getMaxInactiveInterval() * 1000));
       }
     }
   }
   chain.doFilter(req, resp);
 }
 public void destroy() {
 }

}

 </source>

Session logger

   <source lang="java">

//Log4j from Apache is required

import org.apache.log4j.Logger; import org.apache.log4j.PropertyConfigurator; import javax.servlet.*; import javax.servlet.http.*; public class SessionLogger implements HttpSessionListener {

 private Logger log;
 public SessionLogger() {
   /*
    * The loggers are typically initialized by a special initialization
    * listener or servlet. If this is not the case, then initialize the
    * logger here:
    * 
    * java.util.ResourceBundle bundle = java.util.ResourceBundle.getBundle(
    * "com.jexp.global");
    * PropertyConfigurator.configure(bundle.getString(
    * "log-configure-path"));
    */
   log = Logger.getLogger(SessionLogger.class);
 }
 public void sessionCreated(HttpSessionEvent se) {
   //log request of the INFO level
   log.info("HttpSession created: " + se.getSession().getId());
 }
 public void sessionDestroyed(HttpSessionEvent se) {
   //log request about session"s that are invalidated
   log.info("HttpSession invalidated: " + se.getSession().getId());
 }

}

 </source>

Session Tracker

   <source lang="java">

import java.io.PrintWriter; import java.io.IOException; import java.util.Date; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; public class SessionTracker extends HttpServlet {

 public void doGet(HttpServletRequest req, HttpServletResponse res)throws ServletException, IOException 
 {
   res.setContentType("text/html");
   PrintWriter out = res.getWriter();
   HttpSession session = req.getSession(true);
   Integer count = (Integer) session.getAttribute("count");
   if (count == null) {
     count = new Integer(1);
   } else {
     count = new Integer(count.intValue() + 1);
   }
   session.setAttribute("count", count);
   out.println("<html><head><title>SessionSnoop</title></head>");

out.println("<body>

Session Details

");

   out.println("You"ve visited this page " + count + ((count.intValue()== 1) ? " time." : " times.") + "
");

out.println("

Details of this session:

");

   out.println("Session id: " + session.getId() + "
");
   out.println("New session: " + session.isNew() + "
");
   out.println("Timeout: " + session.getMaxInactiveInterval() + "
");
   out.println("Creation time: " + new Date(session.getCreationTime()) + "
");
   out.println("Last access time: " + new Date(session.getLastAccessedTime()) + "
");
   out.println("</body></html>");
 }

}

 </source>

Use cookie to save session data

   <source lang="java">

import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ShoppingCartViewerCookie extends HttpServlet {

 public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException,
     IOException {
   res.setContentType("text/html");
   PrintWriter out = res.getWriter();
   String sessionid = null;
   Cookie[] cookies = req.getCookies();
   if (cookies != null) {
     for (int i = 0; i < cookies.length; i++) {
       if (cookies[i].getName().equals("sessionid")) {
         sessionid = cookies[i].getValue();
         break;
       }
     }
   }
   // If the session ID wasn"t sent, generate one.
   // Then be sure to send it to the client with the response.
   if (sessionid == null) {
     sessionid = generateSessionId();
     Cookie c = new Cookie("sessionid", sessionid);
     res.addCookie(c);
   }
   out.println("<HEAD><TITLE>Current Shopping Cart Items</TITLE></HEAD>");
   out.println("<BODY>");
   // Cart items are associated with the session ID
   String[] items = getItemsFromCart(sessionid);
   // Print the current cart items.
   out.println("You currently have the following items in your cart:
");
   if (items == null) {
     out.println("None");
   } else {

out.println("

" + items[i]); } out.println("

");

   }
   // Ask if they want to add more items or check out.
   out.println("<FORM ACTION=\"/servlet/ShoppingCart\" METHOD=POST>");
   out.println("Would you like to
");
   out.println("<INPUT TYPE=SUBMIT VALUE=\" Add More Items \">");
   out.println("<INPUT TYPE=SUBMIT VALUE=\" Check Out \">");
   out.println("</FORM>");
   // Offer a help page.
   out.println("For help, click ");
   out.println("</BODY></HTML>");
 }
 private static String generateSessionId() throws UnsupportedEncodingException {
   String uid = new java.rmi.server.UID().toString(); // guaranteed unique
   return URLEncoder.encode(uid,"UTF-8"); // encode any special chars
 }
 private static String[] getItemsFromCart(String sessionid) {
   return new String[]{"a","b"};  
 }

}

 </source>

Use hidden fields to save session data

   <source lang="java">

import java.io.IOException; import java.io.PrintWriter; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ShoppingCartViewerHidden extends HttpServlet {

 public void doGet(HttpServletRequest req, HttpServletResponse res)
                              throws ServletException, IOException {
   res.setContentType("text/html");
   PrintWriter out = res.getWriter();
   out.println("<HEAD><TITLE>Current Shopping Cart Items</TITLE></HEAD>");
   out.println("<BODY>");
   // Cart items are passed in as the item parameter.
   String[] items = req.getParameterValues("item");
   // Print the current cart items.
   out.println("You currently have the following items in your cart:
");
   if (items == null) {
     out.println("None");
   }
   else {

out.println("

" + items[i]); } out.println("

");

   }
   // Ask if the user wants to add more items or check out.
   // Include the current items as hidden fields so they"ll be passed on.
   out.println("<FORM ACTION=\"/servlet/ShoppingCart\" METHOD=POST>");
   if (items != null) {
     for (int i = 0; i < items.length; i++) {
       out.println("<INPUT TYPE=HIDDEN NAME=\"item\" VALUE=\"" +
         items[i] + "\">");
     }
   }
   out.println("Would you like to
");
   out.println("<INPUT TYPE=SUBMIT VALUE=\" Add More Items \">");
   out.println("<INPUT TYPE=SUBMIT VALUE=\" Check Out \">");
   out.println("</FORM>");
   out.println("</BODY></HTML>");
 }

}

 </source>

Use URL rewrite to save session data

   <source lang="java">

import java.io.IOException; import java.io.PrintWriter; import java.io.UnsupportedEncodingException; import java.net.URLEncoder; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ShoppingCartViewerRewrite extends HttpServlet {

 public void doGet(HttpServletRequest req, HttpServletResponse res) throws ServletException,
     IOException {
   res.setContentType("text/html");
   PrintWriter out = res.getWriter();
   out.println("<HEAD><TITLE>Current Shopping Cart Items</TITLE></HEAD>");
   out.println("<BODY>");
   // Get the current session ID, or generate one if necessary
   String sessionid = req.getPathInfo();
   if (sessionid == null) {
     sessionid = generateSessionId();
   }
   // Cart items are associated with the session ID
   String[] items = getItemsFromCart(sessionid);
   // Print the current cart items.
   out.println("You currently have the following items in your cart:
");
   if (items == null) {
     out.println("None");
   } else {

out.println("

" + items[i]); } out.println("

");

   }
   // Ask if the user wants to add more items or check out.
   // Include the session ID in the action URL.
   out.println("<FORM ACTION=\"/servlet/ShoppingCart/" + sessionid + "\" METHOD=POST>");
   out.println("Would you like to
");
   out.println("<INPUT TYPE=SUBMIT VALUE=\" Add More Items \">");
   out.println("<INPUT TYPE=SUBMIT VALUE=\" Check Out \">");
   out.println("</FORM>");
   // Offer a help page. Include the session ID in the URL.
   out.println("For help, click ");
   out.println("</BODY></HTML>");
 }
 private static String generateSessionId() throws UnsupportedEncodingException {
   String uid = new java.rmi.server.UID().toString(); // guaranteed unique
   return URLEncoder.encode(uid, "UTF-8"); // encode any special chars
 }
 private static String[] getItemsFromCart(String sessionid) {
   return new String[] { "a", "b" };
 }

}

 </source>

Using Sessions in Servlet

Java/Servlets/Session

Содержание

Fake session

Map adaptor for HttpSession objects

Servlet: session attribute listener

Servlet: Session bind listener

Servlet: Session display

Session Creation and Last-Accessed Time

Servlet Session Example

Servlet : session filter

Servlet: session listener

Servlet: simple session

Session Info

Session Events: implements HttpSessionBindingListener

Session Expiration Filter

Session logger

Session Tracker

Session Details

Details of this session:

Use cookie to save session data

Use hidden fields to save session data

Use URL rewrite to save session data

Using Sessions in Servlet

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