java.security

Class AccessControlContext

java.lang.Object

java.security.AccessControlContext

public final class AccessControlContext
extends Object

An AccessControlContext is used to make system resource access decisions based on the context it encapsulates.

More specifically, it encapsulates a context and has a single method, checkPermission, that is equivalent to the checkPermission method in the AccessController class, with one difference: The AccessControlContext checkPermission method makes access decisions based on the context it encapsulates, rather than that of the current execution thread.

Thus, the purpose of AccessControlContext is for those situations where a security check that should be made within a given context actually needs to be done from within a different context (for example, from within a worker thread).

An AccessControlContext is created by calling the AccessController.getContext method. The getContext method takes a "snapshot" of the current calling context, and places it in an AccessControlContext object, which it returns. A sample call is the following:

 
   AccessControlContext acc = AccessController.getContext()
 
 

Code within a different context can subsequently call the checkPermission method on the previously-saved AccessControlContext object. A sample call is the following:

 
   acc.checkPermission(permission)
 
 

Author:

Roland Schemers

See Also:

AccessController

Constructor Summary

Constructors

Constructor and Description
AccessControlContext(AccessControlContext acc, DomainCombiner combiner) Create a new AccessControlContext with the given AccessControlContext and DomainCombiner.
AccessControlContext(ProtectionDomain[] context) Create an AccessControlContext with the given set of ProtectionDomains.

Method Summary

Methods

Modifier and Type	Method and Description
void	checkPermission(Permission perm) Determines whether the access request indicated by the specified permission should be allowed or denied, based on the security policy currently in effect, and the context in this object.
boolean	equals(Object obj) Checks two AccessControlContext objects for equality.
DomainCombiner	getDomainCombiner() Get the DomainCombiner associated with this AccessControlContext.
int	hashCode() Returns the hash code value for this context.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AccessControlContext

public AccessControlContext(ProtectionDomain[] context)

Create an AccessControlContext with the given set of ProtectionDomains. Context must not be null. Duplicate domains will be removed from the context.

Parameters:

context - the ProtectionDomains associated with this context.

AccessControlContext

public AccessControlContext(AccessControlContext acc,
                    DomainCombiner combiner)

Create a new AccessControlContext with the given AccessControlContext and DomainCombiner. This constructor associates the provided DomainCombiner with the provided AccessControlContext.

Parameters:

acc - the AccessControlContext associated with the provided DomainCombiner.

combiner - the DomainCombiner to be associated with the provided AccessControlContext.

Throws:

NullPointerException - if the provided context is null.

SecurityException - if the caller does not have permission to invoke this constructor.

Method Detail

getDomainCombiner

public DomainCombiner getDomainCombiner()

Get the DomainCombiner associated with this AccessControlContext.

Returns:

the DomainCombiner associated with this AccessControlContext, or null if there is none.

Throws:

SecurityException - if the caller does not have permission to get the DomainCombiner associated with this AccessControlContext.

checkPermission

public void checkPermission(Permission perm)
                     throws AccessControlException

Determines whether the access request indicated by the specified permission should be allowed or denied, based on the security policy currently in effect, and the context in this object.

This method quietly returns if the access request is permitted, or throws a suitable AccessControlException otherwise.

Parameters:

perm - the requested permission.

Throws:

AccessControlException - if the specified permission is not permitted, based on the current security policy and the context encapsulated by this object.

NullPointerException - if the permission to check for is null.

equals

public boolean equals(Object obj)

Checks two AccessControlContext objects for equality. Checks that obj is an AccessControlContext and has the same set of ProtectionDomains as this context.

Overrides:

equals in class Object

Parameters:

obj - the object we are testing for equality with this object.

Returns:

true if obj is an AccessControlContext, and has the same set of ProtectionDomains as this context, false otherwise.

See Also:

Object.hashCode(), Hashtable

hashCode

public int hashCode()

Returns the hash code value for this context. The hash code is computed by exclusive or-ing the hash code of all the protection domains in the context together.

Overrides:

hashCode in class Object

Returns:

a hash code value for this context.

See Also:

Object.equals(java.lang.Object), Hashtable