/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2017 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 *
 *
 * This file incorporates work covered by the following copyright and
 * permission notice:
 *
 * 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.
 */

package javax.servlet.http;

import java.util.Enumeration;
import javax.servlet.ServletContext;

Provides a way to identify a user across more than one page request or visit to a Web site and to store information about that user.

The servlet container uses this interface to create a session between an HTTP client and an HTTP server. The session persists for a specified time period, across more than one connection or page request from the user. A session usually corresponds to one user, who may visit a site many times. The server can maintain a session in many ways such as using cookies or rewriting URLs.

This interface allows servlets to

  • View and manipulate information about a session, such as the session identifier, creation time, and last accessed time
  • Bind objects to sessions, allowing user information to persist across multiple user connections

When an application stores an object in or removes an object from a session, the session checks whether the object implements HttpSessionBindingListener. If it does, the servlet notifies the object that it has been bound to or unbound from the session. Notifications are sent after the binding methods complete. For session that are invalidated or expire, notifications are sent after the session has been invalidated or expired.

When container migrates a session between VMs in a distributed container setting, all session attributes implementing the HttpSessionActivationListener interface are notified.

A servlet should be able to handle cases in which the client does not choose to join a session, such as when cookies are intentionally turned off. Until the client joins the session, isNew returns true. If the client chooses not to join the session, getSession will return a different session on each request, and isNew will always return true.

Session information is scoped only to the current web application (ServletContext), so information stored in one context will not be directly visible in another.

Author: Various
See Also:
/** * * Provides a way to identify a user across more than one page * request or visit to a Web site and to store information about that user. * * <p>The servlet container uses this interface to create a session * between an HTTP client and an HTTP server. The session persists * for a specified time period, across more than one connection or * page request from the user. A session usually corresponds to one * user, who may visit a site many times. The server can maintain a * session in many ways such as using cookies or rewriting URLs. * * <p>This interface allows servlets to * <ul> * <li>View and manipulate information about a session, such as * the session identifier, creation time, and last accessed time * <li>Bind objects to sessions, allowing user information to persist * across multiple user connections * </ul> * * <p>When an application stores an object in or removes an object from a * session, the session checks whether the object implements * {@link HttpSessionBindingListener}. If it does, * the servlet notifies the object that it has been bound to or unbound * from the session. Notifications are sent after the binding methods complete. * For session that are invalidated or expire, notifications are sent after * the session has been invalidated or expired. * * <p> When container migrates a session between VMs in a distributed container * setting, all session attributes implementing the {@link HttpSessionActivationListener} * interface are notified. * * <p>A servlet should be able to handle cases in which * the client does not choose to join a session, such as when cookies are * intentionally turned off. Until the client joins the session, * <code>isNew</code> returns <code>true</code>. If the client chooses * not to join * the session, <code>getSession</code> will return a different session * on each request, and <code>isNew</code> will always return * <code>true</code>. * * <p>Session information is scoped only to the current web application * (<code>ServletContext</code>), so information stored in one context * will not be directly visible in another. * * @author Various * * @see HttpSessionBindingListener * @see HttpSessionContext */
public interface HttpSession {
Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.
Throws:
Returns: a long specifying when this session was created, expressed in milliseconds since 1/1/1970 GMT
/** * * Returns the time when this session was created, measured * in milliseconds since midnight January 1, 1970 GMT. * * @return a <code>long</code> specifying * when this session was created, * expressed in * milliseconds since 1/1/1970 GMT * * @exception IllegalStateException if this method is called on an * invalidated session */
public long getCreationTime();
Returns a string containing the unique identifier assigned to this session. The identifier is assigned by the servlet container and is implementation dependent.
Returns: a string specifying the identifier assigned to this session
/** * Returns a string containing the unique identifier assigned * to this session. The identifier is assigned * by the servlet container and is implementation dependent. * * @return a string specifying the identifier * assigned to this session */
public String getId();
Returns the last time the client sent a request associated with this session, as the number of milliseconds since midnight January 1, 1970 GMT, and marked by the time the container received the request.

Actions that your application takes, such as getting or setting a value associated with the session, do not affect the access time.

Throws:
Returns: a long representing the last time the client sent a request associated with this session, expressed in milliseconds since 1/1/1970 GMT
/** * * Returns the last time the client sent a request associated with * this session, as the number of milliseconds since midnight * January 1, 1970 GMT, and marked by the time the container received the * request. * * <p>Actions that your application takes, such as getting or setting * a value associated with the session, do not affect the access * time. * * @return a <code>long</code> * representing the last time * the client sent a request associated * with this session, expressed in * milliseconds since 1/1/1970 GMT * * @exception IllegalStateException if this method is called on an * invalidated session */
public long getLastAccessedTime();
Returns the ServletContext to which this session belongs.
Returns:The ServletContext object for the web application
Since:Servlet 2.3
/** * Returns the ServletContext to which this session belongs. * * @return The ServletContext object for the web application * @since Servlet 2.3 */
public ServletContext getServletContext();
Specifies the time, in seconds, between client requests before the servlet container will invalidate this session.

An interval value of zero or less indicates that the session should never timeout.

Params:
  • interval – An integer specifying the number of seconds
/** * Specifies the time, in seconds, between client requests before the * servlet container will invalidate this session. * * <p>An <tt>interval</tt> value of zero or less indicates that the * session should never timeout. * * @param interval An integer specifying the number * of seconds */
public void setMaxInactiveInterval(int interval);
Returns the maximum time interval, in seconds, that the servlet container will keep this session open between client accesses. After this interval, the servlet container will invalidate the session. The maximum time interval can be set with the setMaxInactiveInterval method.

A return value of zero or less indicates that the session will never timeout.

See Also:
Returns: an integer specifying the number of seconds this session remains open between client requests
/** * Returns the maximum time interval, in seconds, that * the servlet container will keep this session open between * client accesses. After this interval, the servlet container * will invalidate the session. The maximum time interval can be set * with the <code>setMaxInactiveInterval</code> method. * * <p>A return value of zero or less indicates that the * session will never timeout. * * @return an integer specifying the number of * seconds this session remains open * between client requests * * @see #setMaxInactiveInterval */
public int getMaxInactiveInterval();
Deprecated: As of Version 2.1, this method is deprecated and has no replacement. It will be removed in a future version of the Java Servlet API.
Returns:the HttpSessionContext for this session.
/** * * @deprecated As of Version 2.1, this method is * deprecated and has no replacement. * It will be removed in a future * version of the Java Servlet API. * * @return the {@link HttpSessionContext} for this session. */
@Deprecated public HttpSessionContext getSessionContext();
Returns the object bound with the specified name in this session, or null if no object is bound under the name.
Params:
  • name – a string specifying the name of the object
Throws:
Returns: the object with the specified name
/** * Returns the object bound with the specified name in this session, or * <code>null</code> if no object is bound under the name. * * @param name a string specifying the name of the object * * @return the object with the specified name * * @exception IllegalStateException if this method is called on an * invalidated session */
public Object getAttribute(String name);
Params:
  • name – a string specifying the name of the object
Throws:
Deprecated: As of Version 2.2, this method is replaced by getAttribute.
Returns: the object with the specified name
/** * @deprecated As of Version 2.2, this method is * replaced by {@link #getAttribute}. * * @param name a string specifying the name of the object * * @return the object with the specified name * * @exception IllegalStateException if this method is called on an * invalidated session */
@Deprecated public Object getValue(String name);
Returns an Enumeration of String objects containing the names of all the objects bound to this session.
Throws:
Returns: an Enumeration of String objects specifying the names of all the objects bound to this session
/** * Returns an <code>Enumeration</code> of <code>String</code> objects * containing the names of all the objects bound to this session. * * @return an <code>Enumeration</code> of * <code>String</code> objects specifying the * names of all the objects bound to * this session * * @exception IllegalStateException if this method is called on an * invalidated session */
public Enumeration<String> getAttributeNames();
Throws:
Deprecated: As of Version 2.2, this method is replaced by getAttributeNames
Returns: an array of String objects specifying the names of all the objects bound to this session
/** * @deprecated As of Version 2.2, this method is * replaced by {@link #getAttributeNames} * * @return an array of <code>String</code> * objects specifying the * names of all the objects bound to * this session * * @exception IllegalStateException if this method is called on an * invalidated session */
@Deprecated public String[] getValueNames();
Binds an object to this session, using the name specified. If an object of the same name is already bound to the session, the object is replaced.

After this method executes, and if the new object implements HttpSessionBindingListener, the container calls HttpSessionBindingListener.valueBound. The container then notifies any HttpSessionAttributeListeners in the web application.

If an object was already bound to this session of this name that implements HttpSessionBindingListener, its HttpSessionBindingListener.valueUnbound method is called.

If the value passed in is null, this has the same effect as calling removeAttribute().

Params:
  • name – the name to which the object is bound; cannot be null
  • value – the object to be bound
Throws:
/** * Binds an object to this session, using the name specified. * If an object of the same name is already bound to the session, * the object is replaced. * * <p>After this method executes, and if the new object * implements <code>HttpSessionBindingListener</code>, * the container calls * <code>HttpSessionBindingListener.valueBound</code>. The container then * notifies any <code>HttpSessionAttributeListener</code>s in the web * application. * <p>If an object was already bound to this session of this name * that implements <code>HttpSessionBindingListener</code>, its * <code>HttpSessionBindingListener.valueUnbound</code> method is called. * * <p>If the value passed in is null, this has the same effect as calling * <code>removeAttribute()</code>. * * * @param name the name to which the object is bound; * cannot be null * * @param value the object to be bound * * @exception IllegalStateException if this method is called on an * invalidated session */
public void setAttribute(String name, Object value);
Params:
  • name – the name to which the object is bound; cannot be null
  • value – the object to be bound; cannot be null
Throws:
Deprecated: As of Version 2.2, this method is replaced by setAttribute
/** * @deprecated As of Version 2.2, this method is * replaced by {@link #setAttribute} * * @param name the name to which the object is bound; * cannot be null * * @param value the object to be bound; cannot be null * * @exception IllegalStateException if this method is called on an * invalidated session */
@Deprecated public void putValue(String name, Object value);
Removes the object bound with the specified name from this session. If the session does not have an object bound with the specified name, this method does nothing.

After this method executes, and if the object implements HttpSessionBindingListener, the container calls HttpSessionBindingListener.valueUnbound. The container then notifies any HttpSessionAttributeListeners in the web application.

Params:
  • name – the name of the object to remove from this session
Throws:
/** * Removes the object bound with the specified name from * this session. If the session does not have an object * bound with the specified name, this method does nothing. * * <p>After this method executes, and if the object * implements <code>HttpSessionBindingListener</code>, * the container calls * <code>HttpSessionBindingListener.valueUnbound</code>. The container * then notifies any <code>HttpSessionAttributeListener</code>s in the web * application. * * @param name the name of the object to * remove from this session * * @exception IllegalStateException if this method is called on an * invalidated session */
public void removeAttribute(String name);
Params:
  • name – the name of the object to remove from this session
Throws:
Deprecated: As of Version 2.2, this method is replaced by removeAttribute
/** * @deprecated As of Version 2.2, this method is * replaced by {@link #removeAttribute} * * @param name the name of the object to * remove from this session * * @exception IllegalStateException if this method is called on an * invalidated session */
@Deprecated public void removeValue(String name);
Invalidates this session then unbinds any objects bound to it.
Throws:
  • IllegalStateException – if this method is called on an already invalidated session
/** * Invalidates this session then unbinds any objects bound * to it. * * @exception IllegalStateException if this method is called on an * already invalidated session */
public void invalidate();
Returns true if the client does not yet know about the session or if the client chooses not to join the session. For example, if the server used only cookie-based sessions, and the client had disabled the use of cookies, then a session would be new on each request.
Throws:
Returns: true if the server has created a session, but the client has not yet joined
/** * Returns <code>true</code> if the client does not yet know about the * session or if the client chooses not to join the session. For * example, if the server used only cookie-based sessions, and * the client had disabled the use of cookies, then a session would * be new on each request. * * @return <code>true</code> if the * server has created a session, * but the client has not yet joined * * @exception IllegalStateException if this method is called on an * already invalidated session */
public boolean isNew(); }