HttpSession.java
/*
* 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 jakarta.servlet.http;
import java.util.Enumeration;
import java.util.function.Consumer;
import jakarta.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.
* <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.
* <p>
* This object is <b>only</b> valid within the scope of the HTTP request from which it was obtained. Once the processing
* of that request returns to the container, this object must not be used. If there is a requirement to access the
* session outside of the scope of an HTTP request then this must be done via {@code #getAccessor()}.
*
* @see HttpSessionBindingListener
*/
public interface HttpSession {
/**
* 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
*/
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.
*
* @return a string specifying the identifier assigned to this session
*
* @exception IllegalStateException if this method is called on an invalidated session
*/
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.
* <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
*/
long getLastAccessedTime();
/**
* Returns the ServletContext to which this session belongs.
*
* @return The ServletContext object for the web application
*
* @since Servlet 2.3
*/
ServletContext getServletContext();
/**
* Specifies the time, in seconds, between client requests before the servlet container will invalidate this
* session. A zero or negative time indicates that the session should never timeout.
*
* @param interval An integer specifying the number of seconds
*/
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 <code>setMaxInactiveInterval</code> method. A zero or negative time indicates that
* the session should never timeout.
*
* @return an integer specifying the number of seconds this session remains open between client requests
*
* @see #setMaxInactiveInterval
*/
int getMaxInactiveInterval();
/**
* 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
*/
Object getAttribute(String name);
/**
* 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
*/
Enumeration<String> getAttributeNames();
/**
* 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
*/
void setAttribute(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.
* <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
*/
void removeAttribute(String name);
/**
* Invalidates this session then unbinds any objects bound to it.
*
* @exception IllegalStateException if this method is called on an already invalidated session
*/
void invalidate();
/**
* 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
*/
boolean isNew();
/**
* Provides a mechanism for applications to interact with the {@code HttpSession} outside of the scope of an HTTP
* request.
*/
interface Accessor {
/**
* Call to access the session with the same semantics as if the session was accessed during an HTTP request.
* <p>
* The effect of this call on the session is as if an HTTP request starts; {@link Consumer#accept(Object)} is
* called with the associated session object enabling the application to interact with the session; and, once
* that method returns, the HTTP request ends.
*
* @param sessionConsumer the application provided {@link Consumer} instance that will access the session
*
* @throws IllegalStateException if the session with the ID to which the {@link Accessor} is associated is no
* longer valid
*/
void access(Consumer<HttpSession> sessionConsumer);
}
/**
* Provides a mechanism for applications to interact with the {@code HttpSession} outside of the scope of an HTTP
* request.
*
* @return An {@link Accessor} instance linked to the current session ID (if the session ID is changed the
* {@link Accessor} will no longer be able to access this session)
*
* @throws IllegalStateException if this method is called on an invalid session
*/
default Accessor getAccessor() {
return null;
}
}