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204

Chapter 9 Session Tracking

tener

, its 

valueUnbound

 method is called. With version 2.1 servlets, 

use 

removeValue

. In version 2.2, 

removeAttribute

 is preferred, but 

removeValue

 is still supported (albeit deprecated) for backward com 

patibility.

public String[] getValueNames()

public Enumeration getAttributeNames()

These methods return the names of all attributes in the session. Use 

getValueNames

 in version 2.1 of the servlet specification. In version 

2.2, 

getValueNames

 is supported but deprecated; use 

getAttribute 

Names

 instead.

public String getId()

This method returns the unique identifier generated for each session. It 

is sometimes used as the key name when only a single value is associated 

with a session, or when information about sessions is being logged. 

public boolean isNew()

This method returns 

true

 if the client (browser) has never seen the ses 

sion, usually because it was just created rather than being referenced by 

an incoming client request. It returns 

false

 for preexisting sessions. 

public long getCreationTime()

This method returns the time in milliseconds since midnight, January 1, 

1970 (GMT) at which the session was first built. To get a value useful for 

printing out, pass the value to the 

Date

 constructor or the 

setTimeIn 

Millis

 method of 

GregorianCalendar

. 

public long getLastAccessedTime()

This method returns the time in milliseconds since midnight, January 1, 

1970 (GMT) at which the session was last sent from the client. 

public int getMaxInactiveInterval()

public void setMaxInactiveInterval(int seconds)

These methods get or set the amount of time, in seconds, that a session 

should go without access before being automatically invalidated. A neg 

ative value indicates that the session should never time out. Note that 

the time out is maintained on the server and is not the same as the 

cookie expiration date, which is sent to the client.

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