page 的范围

setAttribute

public abstract void setAttribute(java.lang.String name,
                                  java.lang.Object value,
                                  int scope)

Register the name and value specified with appropriate scope semantics. If the value passed in is null, this has the same effect as callingremoveAttribute( name, scope ).

Parameters:

name - the name of the attribute to set

value - the object to associate with the name, or null if the attribute is to be removed from the specified scope.

scope - the scope with which to associate the name/object

Throws:

java.lang.NullPointerException - if the name is null

IllegalArgumentException - if the scope is invalid

IllegalStateException - if the scope is PageContext.SESSION_SCOPE but the page that was requested does not participate in a session or the session has been invalidated.