ProviderList

Class Overview

This class stores the list of providers that this GSS-Implementation is configured to use. The GSSManagerImpl class queries this class whenever it needs a mechanism's factory.

This class stores an ordered list of pairs of the form . When it attempts to instantiate a mechanism defined by oid o, it steps through the list looking for an entry with oid=o, or with oid=null. (An entry with oid=null matches all mechanisms.) When it finds such an entry, the corresponding provider is approached for the mechanism's factory class. At instantiation time this list in initialized to contain those system wide providers that contain a property of the form "GssApiMechanism.x.y.z..." where "x.y.z..." is a numeric object identifier with numbers x, y, z, etc. Such a property is defined to map to that provider's implementation of the MechanismFactory interface for the mechanism x.y.z... As and when a MechanismFactory is instantiated, it is cached for future use.

An application can cause more providers to be added by means of the addProviderAtFront and addProviderAtEnd methods on GSSManager which get delegated to this class. The addProviderAtFront method can also cause a change in the ordering of the providers without adding any new providers, by causing a provider to move up in a list. The method addProviderAtEnd can only add providers at the end of the list if they are not already in the list. The rationale is that an application will call addProviderAtFront when it wants a provider to be used in preference over the default ones. And it will call addProviderAtEnd when it wants a provider to be used in case the system ones don't suffice.

If a mechanism's factory is being obtained from a provider as a result of encountering a entryof the form where oid is non-null, then the assumption is that the application added this entry and it wants this mechanism to be obtained from this provider. Thus is the provider does not actually contain the requested mechanism, an exception will be thrown. However, if the entry were of the form , then it is viewed more liberally and is simply skipped over if the provider does not claim to support the requested mechanism.

Summary

[Expand] Inherited Methods

From class java.lang.Object Object clone() Creates and returns a copy of this object. boolean equals(Object obj) Indicates whether some other object is "equal to" this one. void finalize() Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. final Class<?> getClass() Returns the runtime class of this Object. int hashCode() Returns a hash code value for the object. final void notify() Wakes up a single thread that is waiting on this object's monitor. final void notifyAll() Wakes up all threads that are waiting on this object's monitor. String toString() Returns a string representation of the object. final void wait() Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object. final void wait(long timeout, int nanos) Causes the current thread to wait until another thread invokes the notify() method or the notifyAll() method for this object, or some other thread interrupts the current thread, or a certain amount of real time has elapsed. final void wait(long timeout) Causes the current thread to wait until either another thread invokes the notify() method or the notifyAll() method for this object, or a specified amount of time has elapsed.