javax.servlet.http

Interface HttpSession

public interface HttpSession

A HttpSession holds session-dependant data on the server side. A servlet can request the servlet by using HttpServletRequest.getSession(...)

The handling of the Session objects is a job done by the server and servlets together.

As follows:

The server maintains the set of HttpSessions.
The server creates HttpSession on request by a servlet
The server removes all invalidated HttpSessions
The server connects an incoming request with its HttpSession (usually done using cookies)
Servlets manipulate the contents of the HttpSession by adding and removing items.
Servlets ask the server to remove HttpSessions by invalidating them

Since:

2.0

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.Object	getAttribute(java.lang.String name) get the attribute value associated with the name
java.util.Enumeration	getAttributeNames() get the list of attribute names
long	getCreationTime() Gets this session's creation time in seconds since january 1st 1970.
java.lang.String	getId() Gets the unique session id.
long	getLastAccessedTime() Gets the number of seconds since the previous access of this session.
int	getMaxInactiveInterval() Returns the minimum time this session will be kept alive by the server when it doesn't get accessed by a client.
ServletContext	getServletContext() Get the ServletContext to which this session belongs
HttpSessionContext	getSessionContext() Deprecated. HttpSessionContext has been deprecated for security reasons.
java.lang.Object	getValue(java.lang.String name) Deprecated. use getAttribute(java.lang.String) instead
java.lang.String[]	getValueNames() Deprecated. use getAttributeNames() instead
void	invalidate() Make this HttpSession unavailable for use by other servlets and tell the server to remove this session.
boolean	isNew() Returns whether this session has been freshly created.
void	putValue(java.lang.String name, java.lang.Object value) Deprecated. Servlet API 2.2 use instead
void	removeAttribute(java.lang.String name) remove the specified attribute.
void	removeValue(java.lang.String name) Deprecated. use removeAttribute(java.lang.String) instead
void	setAttribute(java.lang.String name, java.lang.Object value) set the attribute value to be associated with the name.
void	setMaxInactiveInterval(int interval) Sets the minimum time this session will be kept alive by the server when it doesn't get accessed by a client. Note: hmmm, should an interval of -1 mean that it should live forever?

Method Detail

getCreationTime

long getCreationTime()

Gets this session's creation time in seconds since january 1st 1970.

Returns:

a number of seconds

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

getId

java.lang.String getId()

Gets the unique session id. Every HttpSession has a Id that is unique for this (virtual) http server.

Returns:

The Id

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

getLastAccessedTime

long getLastAccessedTime()

Gets the number of seconds since the previous access of this session. Every time a client's request comes in the server checks (usually by using cookies) which HttpSession object corresponds with this particular client. The server then sets the lastAccessedTime to the current time. (And the isNew flag to false.) If the client has never requested anything with this Session then this method returns -1

Returns:

number of seconds since last access or -1

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

getServletContext

ServletContext getServletContext()

Get the ServletContext to which this session belongs

Returns:

the ServletContext representing the web application of which this session is a part.

Since:

2.3

setMaxInactiveInterval

void setMaxInactiveInterval(int interval)

Sets the minimum time this session will be kept alive by the server when it doesn't get accessed by a client.
Note: hmmm, should an interval of -1 mean that it should live forever?

Parameters:

interval - Probably seconds or -1 if never

Throws:

java.lang.IllegalStateException - if this session has been invalidated

Since:

2.1

getMaxInactiveInterval

int getMaxInactiveInterval()

Returns the minimum time this session will be kept alive by the server when it doesn't get accessed by a client.

Since:

2.1

getSessionContext

HttpSessionContext getSessionContext()

Deprecated. HttpSessionContext has been deprecated for security reasons.

Gets this HttpSession's context. The context contains information that is the same for all HttpSessions for this (virtual) host.

Returns:

The context

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

getAttribute

java.lang.Object getAttribute(java.lang.String name)

get the attribute value associated with the name

Parameters:

name - the name of the attribute

Returns:

the Object associated with this name

Throws:

java.lang.IllegalStateException - if this session has been invalidated

Since:

2.2

getValue

java.lang.Object getValue(java.lang.String name)

Deprecated. use getAttribute(java.lang.String) instead

Gets a object from the set of name/value pairs in the session.

Parameters:

name - the name of the item required

Returns:

the value of the item. null if not present.

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

getAttributeNames

java.util.Enumeration getAttributeNames()

get the list of attribute names

Throws:

java.lang.IllegalStateException - if this session has been invalidated

Since:

2.2

getValueNames

java.lang.String[] getValueNames()

Deprecated. use getAttributeNames() instead

Get a list of all item names in the session.

Returns:

An array of Strings containing all item names.

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

setAttribute

void setAttribute(java.lang.String name,
                java.lang.Object value)

set the attribute value to be associated with the name.

Throws:

java.lang.IllegalStateException - if this session has been invalidated

Since:

2.2

putValue

void putValue(java.lang.String name,
            java.lang.Object value)

Deprecated. Servlet API 2.2 use instead

Puts a name and value in the HttpSession. If the Object implements HttpSessionBindindListener then the valueBound() method of the Object will be called.

Parameters:

name - the name of the item

value - the value of the item

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

removeAttribute

void removeAttribute(java.lang.String name)

remove the specified attribute.

Throws:

java.lang.IllegalStateException - if this session has been invalidated

Since:

2.2

removeValue

void removeValue(java.lang.String name)

Deprecated. use removeAttribute(java.lang.String) instead

Removes an item from the session. If the Object implements HttpSessionBindindListener then the valueUnBound() method of the Object will be called.

Parameters:

name - the name of the item.

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

invalidate

void invalidate()

Make this HttpSession unavailable for use by other servlets and tell the server to remove this session. All values bound to this session with putValue() that implement HttpSessionBindingListener will be called with valueUnbound(). Also: make it throw an IllegalStateException when a servlet tries to execute one of its methods.

Throws:

java.lang.IllegalStateException - if the session has been invalidated.

isNew

boolean isNew()

Returns whether this session has been freshly created. A servlet can ask the server to give the HttpSession connected with this request/client. The Servlet can use this method to check whether the HttpSession has been newly created or if a HttpSession had already been created for a previous request.

Returns:

Whether this is a new HttpSession

Throws:

java.lang.IllegalStateException - if the session has been invalidated.