| javax.servlet.http.HttpSession
| HttpSession | | public interface HttpSession (Code) | | 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: HttpSessionBindingListener
See Also: HttpSessionContext |
| Method 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. | | public Enumeration | getAttributeNames()
Returns an Enumeration of String objects
containing the names of all the objects bound to this session. | | public long | getCreationTime()
Returns the time when this session was created, measured
in milliseconds since midnight January 1, 1970 GMT. | | public String | getId()
Returns a string containing the unique identifier assigned
to this 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. | | public int | getMaxInactiveInterval()
Returns the maximum time interval, in seconds, that
the servlet container will keep this session open between
client accesses. | | public ServletContext | getServletContext()
Returns the ServletContext to which this session belongs. | | public HttpSessionContext | getSessionContext()
| | public Object | getValue(String name)
| | public String[] | getValueNames()
| | public void | invalidate()
Invalidates this session then unbinds any objects bound
to it. | | 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. | | public void | putValue(String name, Object value)
| | public void | removeAttribute(String name)
Removes the object bound with the specified name from
this session. | | public void | removeValue(String name)
| | 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. | | public void | setMaxInactiveInterval(int interval)
Specifies the time, in seconds, between client requests before the
servlet container will invalidate this session. |
| getAttribute | | public Object getAttribute(String name)(Code) | | Returns the object bound with the specified name in this session, or
null if no object is bound under the name.
Parameters:
name - a string specifying the name of the object the object with the specified name
exception:
IllegalStateException - if this method is called on aninvalidated session |
| getAttributeNames | | public Enumeration getAttributeNames()(Code) | | Returns an Enumeration of String objects
containing the names of all the objects bound to this session.
an Enumeration of String objects specifying thenames of all the objects bound tothis session
exception:
IllegalStateException - if this method is called on aninvalidated session |
| getCreationTime | | public long getCreationTime()(Code) | | Returns the time when this session was created, measured
in milliseconds since midnight January 1, 1970 GMT.
a long specifyingwhen this session was created,expressed in milliseconds since 1/1/1970 GMT
exception:
IllegalStateException - if this method is called on aninvalidated session |
| getId | | public String getId()(Code) | | Returns a string containing the unique identifier assigned
to this session. The identifier is assigned
by the servlet container and is implementation dependent.
a string specifying the identifierassigned to this session |
| getLastAccessedTime | | public long getLastAccessedTime()(Code) | | 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.
a longrepresenting the last time the client sent a request associatedwith this session, expressed in milliseconds since 1/1/1970 GMT
exception:
IllegalStateException - if this method is called on aninvalidated session |
| getMaxInactiveInterval | | public int getMaxInactiveInterval()(Code) | | 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 negative time indicates the session should never timeout.
an integer specifying the number ofseconds this session remains openbetween client requests
See Also: HttpSession.setMaxInactiveInterval |
| getServletContext | | public ServletContext getServletContext()(Code) | | Returns the ServletContext to which this session belongs.
The ServletContext object for the web application
since:
2.3 |
| invalidate | | public void invalidate()(Code) | | Invalidates this session then unbinds any objects bound
to it.
exception:
IllegalStateException - if this method is called on analready invalidated session |
| isNew | | public boolean isNew()(Code) | | 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.
true if the server has created a session, but the client has not yet joined
exception:
IllegalStateException - if this method is called on analready invalidated session |
| removeAttribute | | public void removeAttribute(String name)(Code) | | 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 - the name of the object toremove from this session
exception:
IllegalStateException - if this method is called on aninvalidated session |
| setAttribute | | public void setAttribute(String name, Object value)(Code) | | 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 - the name to which the object is bound;cannot be null
Parameters:
value - the object to be bound
exception:
IllegalStateException - if this method is called on aninvalidated session |
| setMaxInactiveInterval | | public void setMaxInactiveInterval(int interval)(Code) | | Specifies the time, in seconds, between client requests before the
servlet container will invalidate this session. A negative time
indicates the session should never timeout.
Parameters:
interval - An integer specifying the numberof seconds |
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