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public 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 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
returnstrue
. If the client chooses not to join the session,getSession
will return a different session on each request, andisNew
will always returntrue
.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
,HttpSessionContext
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Method Summary
All Methods Instance Methods Abstract Methods Deprecated Methods Modifier and Type Method and Description Object
getAttribute(String name)
Returns the object bound with the specified name in this session, ornull
if no object is bound under the name.Enumeration<String>
getAttributeNames()
Returns anEnumeration
ofString
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.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 received 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.Object
getValue(String name)
Deprecated.As of Version 2.2, this method is replaced bygetAttribute(java.lang.String)
.String[]
getValueNames()
Deprecated.As of Version 2.2, this method is replaced bygetAttributeNames()
void
invalidate()
Invalidates this session then unbinds any objects bound to it.boolean
isNew()
Returnstrue
if the client does not yet know about the session or if the client chooses not to join the session.void
putValue(String name, Object value)
Deprecated.As of Version 2.2, this method is replaced bysetAttribute(java.lang.String, java.lang.Object)
void
removeAttribute(String name)
Removes the object bound with the specified name from this session.void
removeValue(String name)
Deprecated.As of Version 2.2, this method is replaced byremoveAttribute(java.lang.String)
void
setAttribute(String name, 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.
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Method Detail
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getCreationTime
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
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getId
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
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getLastAccessedTime
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:
- a
long
representing the last time the client sent a request associated with this session, expressed in milliseconds since 1/1/1970 GMT - Throws:
IllegalStateException
- if this method is called on an invalidated session
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getServletContext
ServletContext getServletContext()
Returns the ServletContext to which this session belongs.- Returns:
- The ServletContext object for the web application
- Since:
- Servlet 2.3
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setMaxInactiveInterval
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
- An integer specifying the number of seconds
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getMaxInactiveInterval
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 thesetMaxInactiveInterval
method.A return value of zero or less indicates that the session will never timeout.
- Returns:
- an integer specifying the number of seconds this session remains open between client requests
- See Also:
setMaxInactiveInterval(int)
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getSessionContext
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.
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getAttribute
Object getAttribute(String name)
Returns the object bound with the specified name in this session, ornull
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
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getValue
Object getValue(String name)
Deprecated. As of Version 2.2, this method is replaced bygetAttribute(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
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getAttributeNames
Enumeration<String> getAttributeNames()
Returns anEnumeration
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
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getValueNames
String[] getValueNames()
Deprecated. As of Version 2.2, this method is replaced bygetAttributeNames()
- 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
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setAttribute
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 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
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putValue
void putValue(String name, Object value)
Deprecated. As of Version 2.2, this method is replaced bysetAttribute(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
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removeAttribute
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 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
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removeValue
void removeValue(String name)
Deprecated. As of Version 2.2, this method is replaced byremoveAttribute(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
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invalidate
void invalidate()
Invalidates this session then unbinds any objects bound to it.- Throws:
IllegalStateException
- if this method is called on an already invalidated session
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isNew
boolean isNew()
Returnstrue
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
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Nederlandse vertaling
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Bij voorbaat dank.
Document heeft de 11/06/2005 gemaakt, de laatste keer de 18/08/2025 gewijzigd
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