EE4J 10.0.0 · jakarta.servlet.http.HttpSession

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.

Method Summary

Modifier and Type	Method and Description
public Object	Returns: the object with the specified name getAttribute(String a string specifying the name of the object name) Returns the object bound with the specified name in this session, or `null` if no object is bound under the name.
public Enumeration<String>	Returns: an `Enumeration` of `String` objects specifying the names of all the objects bound to this session getAttributeNames() Returns an `Enumeration` of `String` objects containing the names of all the objects bound to this session.
public long	Returns: a `long` specifying when this session was created, expressed in milliseconds since 1/1/1970 GMT getCreationTime() Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.
public String	Returns: a string specifying the identifier assigned to this session getId() Returns a string containing the unique identifier assigned to this session.
public long	Returns: a `long` representing the last time the client sent a request associated with this session, expressed in milliseconds since 1/1/1970 GMT getLastAccessedTime() 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.
public int	Returns: an integer specifying the number of seconds this session remains open between client requests getMaxInactiveInterval() Returns the maximum time interval, in seconds, that the servlet container will keep this session open between client accesses.
public ServletContext	Returns: The ServletContext object for the web application getServletContext() Returns the ServletContext to which this session belongs.
public void	invalidate() Invalidates this session then unbinds any objects bound to it.
public boolean	Returns: `true` if the server has created a session, but the client has not yet joined isNew() Returns `true` if the client does not yet know about the session or if the client chooses not to join the session.
public void	removeAttribute(String the name of the object to remove from this session name) Removes the object bound with the specified name from this session.
public void	setAttribute(String the name to which the object is bound; cannot be null name, Object the object to be bound value) Binds an object to this session, using the name specified.
public void	setMaxInactiveInterval(int An integer specifying the number of seconds interval) Specifies the time, in seconds, between client requests before the servlet container will invalidate this session.

Method Detail

getAttribute back to summary

getAttribute	back to summary
public Object getAttribute(String name) Returns the object bound with the specified name in this session, or `null` if no object is bound under the name. Parameters name:String a string specifying the name of the object Returns:Object the object with the specified name Exceptions IllegalStateException: if this method is called on an invalidated session

public Object getAttribute(String name)

Returns the object bound with the specified name in this session, or null if no object is bound under the name.

Parameters

name:String: a string specifying the name of the object

Returns:Object

the object with the specified name

Exceptions

IllegalStateException:: if this method is called on an invalidated session

getAttributeNames back to summary

getAttributeNames	back to summary
public Enumeration<String> getAttributeNames() Returns an `Enumeration` of `String` objects containing the names of all the objects bound to this session. Returns:Enumeration<String> an `Enumeration` of `String` objects specifying the names of all the objects bound to this session Exceptions IllegalStateException: if this method is called on an invalidated session

public Enumeration<String> getAttributeNames()

Returns an Enumeration of String objects containing the names of all the objects bound to this session.

Returns:Enumeration<String>

an Enumeration of String objects specifying the names of all the objects bound to this session

Exceptions

IllegalStateException:: if this method is called on an invalidated session

getCreationTime back to summary

getCreationTime	back to summary
public long getCreationTime() Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT. Returns:long a `long` specifying when this session was created, expressed in milliseconds since 1/1/1970 GMT Exceptions IllegalStateException: if this method is called on an invalidated session

public long getCreationTime()

Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.

Returns:long

a long specifying when this session was created, expressed in milliseconds since 1/1/1970 GMT

Exceptions

IllegalStateException:: if this method is called on an invalidated session

getId	back to summary
public String getId() Returns a string containing the unique identifier assigned to this session. The identifier is assigned by the servlet container and is implementation dependent. Returns:String a string specifying the identifier assigned to this session

getId

back to summary

public String getId()

Returns a string containing the unique identifier assigned to this session. The identifier is assigned by the servlet container and is implementation dependent.

Returns:String: a string specifying the identifier assigned to this session

getLastAccessedTime back to summary

getLastAccessedTime	back to summary
public long getLastAccessedTime() 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. Returns:long a `long` representing the last time the client sent a request associated with this session, expressed in milliseconds since 1/1/1970 GMT Exceptions IllegalStateException: if this method is called on an invalidated session

public long getLastAccessedTime()

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.

Returns:long

a long representing the last time the client sent a request associated with this session, expressed in milliseconds since 1/1/1970 GMT

Exceptions

IllegalStateException:: if this method is called on an invalidated session

getMaxInactiveInterval back to summary

getMaxInactiveInterval	back to summary
public int getMaxInactiveInterval() 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. Returns:int an integer specifying the number of seconds this session remains open between client requests See Also `setMaxInactiveInterval`

public int getMaxInactiveInterval()

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.

Returns:int: an integer specifying the number of seconds this session remains open between client requests
See Also: setMaxInactiveInterval

getServletContext	back to summary
public ServletContext getServletContext() Returns the ServletContext to which this session belongs. Returns:ServletContext The ServletContext object for the web application Since Servlet 2.3

getServletContext

back to summary

public ServletContext getServletContext()

Returns the ServletContext to which this session belongs.

Returns:ServletContext: The ServletContext object for the web application
Since: Servlet 2.3

invalidate	back to summary
public void invalidate() Invalidates this session then unbinds any objects bound to it. Exceptions IllegalStateException: if this method is called on an already invalidated session

invalidate

back to summary

public void invalidate()

Invalidates this session then unbinds any objects bound to it.

Exceptions

IllegalStateException:: if this method is called on an already invalidated session

isNew back to summary

isNew	back to summary
public boolean isNew() 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. Returns:boolean `true` if the server has created a session, but the client has not yet joined Exceptions IllegalStateException: if this method is called on an already invalidated session

public boolean isNew()

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.

Returns:boolean

true if the server has created a session, but the client has not yet joined

Exceptions

IllegalStateException:: if this method is called on an already invalidated session

removeAttribute back to summary

removeAttribute	back to summary
public void removeAttribute(String name) 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 `HttpSessionAttributeListener`s in the web application. Parameters name:String the name of the object to remove from this session Exceptions IllegalStateException: if this method is called on an invalidated session

public void removeAttribute(String name)

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.

Parameters

name:String: the name of the object to remove from this session

Exceptions

IllegalStateException:: if this method is called on an invalidated session

setAttribute back to summary

setAttribute	back to summary
public void setAttribute(String name, Object value) 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 `HttpSessionAttributeListener`s 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()`. Parameters name:String the name to which the object is bound; cannot be null value:Object the object to be bound Exceptions IllegalStateException: if this method is called on an invalidated session

public void setAttribute(String name, Object value)

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().

Parameters

name:String: the name to which the object is bound; cannot be null
value:Object: the object to be bound

Exceptions

IllegalStateException:: if this method is called on an invalidated session

setMaxInactiveInterval back to summary

setMaxInactiveInterval	back to summary
public void setMaxInactiveInterval(int interval) 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. Parameters interval:int An integer specifying the number of seconds

public void setMaxInactiveInterval(int interval)

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.

Parameters

interval:int: An integer specifying the number of seconds

public Interface HttpSession

Method Summary

Method Detail