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Interface javax.servlet.http.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 maintaines 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

Version:
Servlet API 2.0

Method Index

 o getCreationTime()
Gets this session's creation time in seconds since january 1st 1970.
 o getId()
Gets the unique session id.
 o getLastAccessedTime()
Gets the number of seconds since the previous access of this session.
 o getSessionContext()
Gets this HttpSession's context.
 o getValue(String)
Gets a object from the set of name/value pairs in the session.
 o getValueNames()
Get a list of all item names in the session.
 o invalidate()
Make this HttpSession unavailable for use by other servlets and tell the server to remove this session.
 o isNew()
Returns whether this session has been freshly created.
 o putValue(String, Object)
Puts a name and value in the HttpSession.
 o removeValue(String)
Removes an item from the session.

Methods

 o getCreationTime
 public abstract long getCreationTime() throws IllegalStateException
Gets this session's creation time in seconds since january 1st 1970.

Returns:
a number of seconds
Throws: IllegalStateException
if the session has been invalidated.
 o getId
 public abstract String getId() throws IllegalStateException
Gets the unique session id. Every HttpSession has a Id that is unique for this (virtual) http server.

Returns:
The Id
Throws: IllegalStateException
if the session has been invalidated.
 o getLastAccessedTime
 public abstract long getLastAccessedTime() throws IllegalStateException
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: IllegalStateException
if the session has been invalidated.
 o getValue
 public abstract Object getValue(String name) throws IllegalStateException
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: IllegalStateException
if the session has been invalidated.
 o getValueNames
 public abstract String[] getValueNames() throws IllegalStateException
Get a list of all item names in the session.

Returns:
An array of Strings containing all item names.
Throws: IllegalStateException
if the session has been invalidated.
 o invalidate
 public abstract void invalidate() throws IllegalStateException
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: IllegalStateException
if the session has been invalidated.
 o isNew
 public abstract boolean isNew() throws IllegalStateException
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: IllegalStateException
if the session has been invalidated.
 o putValue
 public abstract void putValue(String name,
                               Object value) throws IllegalStateException
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: IllegalStateException
if the session has been invalidated.
 o removeValue
 public abstract void removeValue(String name) throws IllegalStateException
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: IllegalStateException
if the session has been invalidated.
 o getSessionContext
 public abstract HttpSessionContext getSessionContext() throws IllegalStateException
Gets this HttpSession's context. The context contains information that is the same for all HttpSessions for this (virtual) host.

Returns:
The context
Throws: IllegalStateException
if the session has been invalidated.

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