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 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
- Since:
- Servlet API 2.0
- Version:
- Servlet API 2.0
Method Summary |
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.
|
HttpSessionContext |
getSessionContext()
Gets this HttpSession's context.
|
java.lang.Object |
getValue(java.lang.String name)
Gets a object from the set of name/value pairs in the session. |
java.lang.String[] |
getValueNames()
Get a list of all item names in the session. |
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)
Puts a name and value in the HttpSession.
|
void |
removeValue(java.lang.String name)
Removes an item from the session.
|
getCreationTime
public long getCreationTime()
throws java.lang.IllegalStateException
- 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.
- Since:
- Servlet API 2.0
getId
public java.lang.String getId()
throws java.lang.IllegalStateException
- 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.
- Since:
- Servlet API 2.0
getLastAccessedTime
public long getLastAccessedTime()
throws java.lang.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:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0
getValue
public java.lang.Object getValue(java.lang.String name)
throws java.lang.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:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0
getValueNames
public java.lang.String[] getValueNames()
throws java.lang.IllegalStateException
- 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.
- Since:
- Servlet API 2.0
invalidate
public void invalidate()
throws java.lang.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:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0
isNew
public boolean isNew()
throws java.lang.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:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0
putValue
public void putValue(java.lang.String name,
java.lang.Object value)
throws java.lang.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 itemvalue
- the value of the item- Throws:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0
removeValue
public void removeValue(java.lang.String name)
throws java.lang.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:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0
getSessionContext
public HttpSessionContext getSessionContext()
throws java.lang.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:
- java.lang.IllegalStateException - if the session has been invalidated.
- Since:
- Servlet API 2.0