public final class PolicyContext
extends java.lang.Object
Policy providers. Policy providers use the policy context identifier to select the
subset of policy to apply in access decisions.
The value of a policy context identifier is a
String and each thread has an independently established policy context identifier. A container will establish
the thread-scoped value of a policy context identifier by calling the static setContextID method. The
value of a thread-scoped policy context identifier is available (to Policy) by calling the static
getContextID method.
This class is also used by Policy providers to request additional thread-scoped policy relevant context
objects from the calling container. Containers register container-specific PolicyContext handlers using
the static registerHandler method. Handler registration is scoped to the class, such that the same
handler registrations are active in all thread contexts. Containers may use the static method
setHandlerData to establish a thread-scoped parameter that will be passed to handlers when they are
activated by Policy providers. The static getContext method is used to activate a handler
and obtain the corresponding context object.
The static accessor functions provided by this class allow per-thread policy context values to be established and communicated independent of a common reference to a particular PolicyContext instance.
The PolicyContext class may encapsulate static ThreadLocal instance variables to represent the policy context identifier and handler data values.
The Application server must bundle or install the PolicyContext class, and the containers of the application server must prevent the methods of the PolicyContext class from being called from calling contexts that are not authorized to call these methods. With the exception of the getContextID and GetHandlerKeys methods, containers must restrict and afford access to the methods of the PolicyContext class to calling contexts trusted by the container to perform container access decisions. The PolicyContext class may satisfy this requirement (on behalf of its container) by rejecting calls made from an AccessControlContext that has not been granted the "setPolicy" SecurityPermission, and by ensuring that Policy providers used to perform container access decisions are granted the "setPolicy" permission.
PolicyContextHandler| Modifier and Type | Method and Description |
|---|---|
static <T> T |
getContext(java.lang.String key)
This method may be used by a
Policy provider to activate the PolicyContextHandler
registered to the context object key and cause it to return the corresponding policy context object from the
container. |
static java.lang.String |
getContextID()
This static method returns the value of the policy context identifier associated with the thread on which the
accessor is called.
|
static java.util.Set |
getHandlerKeys()
This method may be used to obtain the keys that identify the container specific context handlers registered by the
container.
|
static void |
registerHandler(java.lang.String key,
PolicyContextHandler handler,
boolean replace)
Authorization protected method used to register a container specific
PolicyContext handler. |
static void |
setContextID(java.lang.String contextID)
Authorization protected method used to modify the value of the policy context identifier associated with the thread
on which this method is called.
|
static void |
setHandlerData(java.lang.Object data)
Authorization protected method that may be used to associate a thread-scoped handler data object with the
PolicyContext.
|
public static void setContextID(java.lang.String contextID)
contextID - a String that represents the value of the policy context identifier to be assigned to
the PolicyContext for the calling thread. The value null
is a legitimate value for this parameter.java.lang.SecurityException - if the calling AccessControlContext is not authorized by the container to call
this method.public static java.lang.String getContextID()
String (or null) policy context identifier established for the thread. This
method must return the default policy context identifier, null, if the policy context identifier of the
thread has not been set via setContext to another value.java.lang.SecurityException - if the calling AccessControlContext is not authorized by the container to call
this method. Containers may choose to authorize calls to this method by any AccessControlContext.public static void setHandlerData(java.lang.Object data)
data - a container-specific object that will be associated with the calling thread and passed to any handler
activated by a Policy provider (on the thread). The value null is a legitimate value for
this parameter, and is the value that will be used in the activation of handlers if the setHandlerData
has not been called on the thread.java.lang.SecurityException - if the calling AccessControlContext is not authorized by the container to call
this method.public static void registerHandler(java.lang.String key,
PolicyContextHandler handler,
boolean replace)
throws PolicyContextException
PolicyContext handler. A handler
may be registered to handle multiple keys, but at any time, at most one handler may be registered for a key.key - a (case-sensitive) String that identifies the context object handled by the handler. The
value of this parameter must not be null.handler - an object that implements the PolicyContextHandler interface. The value of this parameter
must not be null.replace - this boolean value defines the behavior of this method if, when it is called, a
PolicyContextHandler has already been registered to handle the same key. In that case, and if the value
of this argument is true, the existing handler is replaced with the argument handler. If the value of
this parameter is false the existing registration is preserved and an exception is thrown.java.lang.IllegalArgumentException - if the value of either of the handler or key arguments is null, or the
value of the replace argument is false and a handler with the same key as the argument handler is
already registered.java.lang.SecurityException - if the calling AccessControlContext is not authorized by the container to call
this method.PolicyContextException - if an operation by this method on the argument
PolicyContextHandler causes it to throw a checked exception that is not accounted for in the signature of this
method.public static java.util.Set getHandlerKeys()
Set, the elements of which, are the String key values that identify the handlers
that have been registered and therefore may be activated on the PolicyContext.java.lang.SecurityException - if the calling AccessControlContext is not authorized by the container to call
this method. Containers may choose to authorize calls to this method by any AccessControlContext.public static <T> T getContext(java.lang.String key)
throws PolicyContextException
Policy provider to activate the PolicyContextHandler
registered to the context object key and cause it to return the corresponding policy context object from the
container. When this method activates a handler, it passes to the handler the context object key and the handler data
associated with the calling thread.key - a String that identifies the PolicyContextHandler to activate and the context
object to be acquired from the handler. The value of this parameter must not be null.null value is
returned if the corresponding handler has been registered, and the value of the corresponding context is null.java.lang.IllegalArgumentException - if a PolicyContextHandler has not been registered for the key
or the registered handler no longer supports the key.java.lang.SecurityException - if the calling AccessControlContext is not authorized by the container to call
this method.PolicyContextException - if an operation by this method on the identified
PolicyContextHandler causes it to throw a checked exception that is not accounted for in the signature of this
method.