Class PermissionCollection
- All Implemented Interfaces:
Serializable
- Direct Known Subclasses:
Permissions
With a PermissionCollection
, you can:
- add a permission to the collection using the
add
method. - check to see if a particular permission is implied in the
collection, using the
implies
method. - enumerate all the permissions, using the
elements
method.
When it is desirable to group together a number of Permission
objects of the same type, the newPermissionCollection
method on that
particular type of Permission
object should first be called. The
default behavior (from the Permission
class) is to simply return
null
. Subclasses of class Permission
override the method if
they need to store their permissions in a particular
PermissionCollection
object in order to provide the correct
semantics when the PermissionCollection.implies
method is called.
If a non-null value is returned, that PermissionCollection
must be
used. If null
is returned, then the caller of
newPermissionCollection
is free to store permissions of the
given type in any PermissionCollection
they choose
(one that uses a Hashtable
, one that uses a Vector
, etc.).
The collection returned by the Permission.newPermissionCollection
method is a homogeneous collection, which stores only Permission
objects for a given permission type. A PermissionCollection
may
also be heterogeneous. For example, Permissions
is a
PermissionCollection
subclass that represents a collection of
PermissionCollection
objects.
That is, its members are each a homogeneous PermissionCollection
.
For example, a Permission
object might have a
FilePermissionCollection
for all the FilePermission
objects,
a SocketPermissionCollection
for all the SocketPermission
objects, and so on. Its add
method adds a
permission to the appropriate collection.
Whenever a permission is added to a heterogeneous
PermissionCollection
such as Permissions
, and the
PermissionCollection
doesn't yet contain a
PermissionCollection
of the specified permission's type, the
PermissionCollection
should call
the newPermissionCollection
method on the permission's class
to see if it requires a special PermissionCollection
. If
newPermissionCollection
returns null
, the PermissionCollection
is free to store the permission in any type of PermissionCollection
it desires (one using a Hashtable
, one using a Vector
, etc.).
For example, the Permissions
object uses a default
PermissionCollection
implementation that stores the permission
objects in a Hashtable
.
Subclass implementations of PermissionCollection
should assume
that they may be called simultaneously from multiple threads,
and therefore should be synchronized properly. Furthermore,
Enumerations returned via the elements
method are
not fail-fast. Modifications to a collection should not be
performed while enumerating over that collection.
- Since:
- 1.2
- See Also:
-
Constructor Summary
-
Method Summary
Modifier and TypeMethodDescriptionabstract void
add
(Permission permission) Adds a permission object to the current collection of permission objects.abstract Enumeration
<Permission> elements()
Returns an enumeration of all the Permission objects in the collection.Returns a stream of all the Permission objects in the collection.abstract boolean
implies
(Permission permission) Checks to see if the specified permission is implied by the collection ofPermission
objects held in thisPermissionCollection
.boolean
Returnstrue
if thisPermissionCollection
object is marked as readonly.void
Marks thisPermissionCollection
object as "readonly".toString()
Returns a string describing thisPermissionCollection
object, providing information about all the permissions it contains.
-
Constructor Details
-
PermissionCollection
public PermissionCollection()Constructor for subclasses to call.
-
-
Method Details
-
add
Adds a permission object to the current collection of permission objects.- Parameters:
permission
- the Permission object to add.- Throws:
SecurityException
- if thisPermissionCollection
object has been marked readonlyIllegalArgumentException
- if thisPermissionCollection
object is a homogeneous collection and the permission is not of the correct type.
-
implies
Checks to see if the specified permission is implied by the collection ofPermission
objects held in thisPermissionCollection
.- Parameters:
permission
- thePermission
object to compare.- Returns:
true
if "permission" is implied by the permissions in the collection,false
if not.
-
elements
Returns an enumeration of all the Permission objects in the collection.- Returns:
- an enumeration of all the Permissions.
- See Also:
-
elementsAsStream
Returns a stream of all the Permission objects in the collection.The collection should not be modified (see
add(java.security.Permission)
) during the execution of the terminal stream operation. Otherwise, the result of the terminal stream operation is undefined.- Implementation Requirements:
- The default implementation creates a stream whose source is derived from
the enumeration returned from a call to
elements()
. - Returns:
- a stream of all the Permissions.
- Since:
- 9
-
setReadOnly
public void setReadOnly()Marks thisPermissionCollection
object as "readonly". After aPermissionCollection
object is marked as readonly, no newPermission
objects can be added to it usingadd
. -
isReadOnly
public boolean isReadOnly()Returnstrue
if thisPermissionCollection
object is marked as readonly. If it is readonly, no newPermission
objects can be added to it usingadd
.By default, the object is not readonly. It can be set to readonly by a call to
setReadOnly
.- Returns:
true
if thisPermissionCollection
object is marked as readonly,false
otherwise.
-
toString
Returns a string describing thisPermissionCollection
object, providing information about all the permissions it contains. The format is:super.toString() ( // enumerate all the Permission // objects and call toString() on them, // one per line.. )
super.toString
is a call to thetoString
method of this object's superclass, which isObject
. The result is this collection's type name followed by this object's hashcode, thus enabling clients to differentiate differentPermissionCollection
objects, even if they contain the same permissions.
-