|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |
javax.servlet.http Interface HttpSession
- public abstract interface 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 invalidatd or expired.
When container migrates a session between VMs in a distributed container
setting, all session atributes 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.
- See Also:
HttpSessionBindingListener
,HttpSessionContext
Method Summary | |
java.lang.Object |
getAttribute(java.lang.String name)
Returns the object bound with the specified name in this session, or null if no object is bound under the name. |
java.util.Enumeration |
getAttributeNames()
Returns an Enumeration of String objects
containing the names of all the objects bound to this session. |
long |
getCreationTime()
Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT. |
java.lang.String |
getId()
Returns a string containing the unique identifier assigned to this session. |
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 recieved the request. |
int |
getMaxInactiveInterval()
Returns the maximum time interval, in seconds, that the servlet container will keep this session open between client accesses. |
ServletContext |
getServletContext()
Returns the ServletContext to which this session belongs. |
HttpSessionContext |
getSessionContext()
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. |
java.lang.Object |
getValue(java.lang.String name)
Deprecated. As of Version 2.2, this method is replaced by getAttribute(java.lang.String) . |
java.lang.String[] |
getValueNames()
Deprecated. As of Version 2.2, this method is replaced by getAttributeNames() |
void |
invalidate()
Invalidates this session then unbinds any objects bound to it. |
boolean |
isNew()
Returns true if the client does not yet know about the
session or if the client chooses not to join the session. |
void |
putValue(java.lang.String name,
java.lang.Object value)
Deprecated. As of Version 2.2, this method is replaced by setAttribute(java.lang.String, java.lang.Object) |
void |
removeAttribute(java.lang.String name)
Removes the object bound with the specified name from this session. |
void |
removeValue(java.lang.String name)
Deprecated. As of Version 2.2, this method is replaced by removeAttribute(java.lang.String) |
void |
setAttribute(java.lang.String name,
java.lang.Object value)
Binds an object to this session, using the name specified. |
void |
setMaxInactiveInterval(int interval)
Specifies the time, in seconds, between client requests before the servlet container will invalidate this session. |
Method Detail |
getCreationTime
public long getCreationTime()
- Returns the time when this session was created, measured in milliseconds since midnight January 1, 1970 GMT.
- Returns:
- a
long
specifying when this session was created, expressed in milliseconds since 1/1/1970 GMT - Throws:
- IllegalStateException - if this method is called on an invalidated session
getId
public java.lang.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:
- a string specifying the identifier assigned to this session
getLastAccessedTime
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 recieved 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:
- a
long
representing the last time the client sent a request associated with this session, expressed in milliseconds since 1/1/1970 GMT
getServletContext
public ServletContext getServletContext()
- Returns the ServletContext to which this session belongs.
- Returns:
- The ServletContext object for the web application
- Since:
- 2.3
setMaxInactiveInterval
public void setMaxInactiveInterval(int interval)
- 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 number of seconds
getMaxInactiveInterval
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 negative time indicates the session should never timeout. - Returns:
- an integer specifying the number of seconds this session remains open between client requests
- See Also:
setMaxInactiveInterval(int)
getSessionContext
public HttpSessionContext getSessionContext()
- 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.
getAttribute
public java.lang.Object getAttribute(java.lang.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
- a string specifying the name of the object- Returns:
- the object with the specified name
- Throws:
- IllegalStateException - if this method is called on an invalidated session
getValue
public java.lang.Object getValue(java.lang.String name)
- Deprecated. As of Version 2.2, this method is
replaced by
getAttribute(java.lang.String)
. - Parameters:
name
- a string specifying the name of the object- Returns:
- the object with the specified name
- Throws:
- IllegalStateException - if this method is called on an invalidated session
getAttributeNames
public java.util.Enumeration getAttributeNames()
- Returns an
Enumeration
ofString
objects containing the names of all the objects bound to this session. - Returns:
- an
Enumeration
ofString
objects specifying the names of all the objects bound to this session - Throws:
- IllegalStateException - if this method is called on an invalidated session
getValueNames
public java.lang.String[] getValueNames()
- 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 - Throws:
- IllegalStateException - if this method is called on an invalidated session
setAttribute
public void setAttribute(java.lang.String name, java.lang.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 callsHttpSessionBindingListener.valueBound
. The container then notifies anyHttpSessionAttributeListener
s in the web application.If an object was already bound to this session of this name that implements
HttpSessionBindingListener
, itsHttpSessionBindingListener.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 nullvalue
- the object to be bound- Throws:
- IllegalStateException - if this method is called on an invalidated session
putValue
public void putValue(java.lang.String name, java.lang.Object value)
- Deprecated. As of Version 2.2, this method is
replaced by
setAttribute(java.lang.String, java.lang.Object)
- Parameters:
name
- the name to which the object is bound; cannot be nullvalue
- the object to be bound; cannot be null- Throws:
- IllegalStateException - if this method is called on an invalidated session
removeAttribute
public void removeAttribute(java.lang.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 callsHttpSessionBindingListener.valueUnbound
. The container then notifies anyHttpSessionAttributeListener
s in the web application. - Parameters:
name
- the name of the object to remove from this session- Throws:
- IllegalStateException - if this method is called on an invalidated session
removeValue
public void removeValue(java.lang.String name)
- Deprecated. As of Version 2.2, this method is
replaced by
removeAttribute(java.lang.String)
- Parameters:
name
- the name of the object to remove from this session- Throws:
- IllegalStateException - if this method is called on an invalidated session
invalidate
public void invalidate()
- Invalidates this session then unbinds any objects bound to it.
- Throws:
- IllegalStateException - if this method is called on an already invalidated session
isNew
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:
true
if the server has created a session, but the client has not yet joined- Throws:
- IllegalStateException - if this method is called on an already invalidated session
|
|||||||||
PREV CLASS NEXT CLASS | FRAMES NO FRAMES | ||||||||
SUMMARY: INNER | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |