- All Implemented Interfaces:
Serializable
- Direct Known Subclasses:
Permissions
With a PermissionCollection, you can:
- add a permission to the collection using the
addmethod. - check to see if a particular permission is implied in the
collection, using the
impliesmethod. - enumerate all the permissions, using the
elementsmethod.
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:
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionabstract voidadd(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 booleanimplies(Permission permission) Checks to see if the specified permission is implied by the collection ofPermissionobjects held in thisPermissionCollection.booleanReturnstrueif thisPermissionCollectionobject is marked as readonly.voidMarks thisPermissionCollectionobject as "readonly".toString()Returns a string describing thisPermissionCollectionobject, providing information about all the permissions it contains.
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Constructor Details
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PermissionCollection
public PermissionCollection()Constructor for subclasses to call.
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Method Details
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add
Adds a permission object to the current collection of permission objects.- Parameters:
permission- the Permission object to add.- Throws:
SecurityException- if thisPermissionCollectionobject has been marked readonlyIllegalArgumentException- if thisPermissionCollectionobject is a homogeneous collection and the permission is not of the correct type.
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implies
Checks to see if the specified permission is implied by the collection ofPermissionobjects held in thisPermissionCollection.- Parameters:
permission- thePermissionobject to compare.- Returns:
trueif "permission" is implied by the permissions in the collection,falseif not.
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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
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setReadOnly
public void setReadOnly()Marks thisPermissionCollectionobject as "readonly". After aPermissionCollectionobject is marked as readonly, no newPermissionobjects can be added to it usingadd. -
isReadOnly
public boolean isReadOnly()Returnstrueif thisPermissionCollectionobject is marked as readonly. If it is readonly, no newPermissionobjects 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:
trueif thisPermissionCollectionobject is marked as readonly,falseotherwise.
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toString
Returns a string describing thisPermissionCollectionobject, 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.toStringis a call to thetoStringmethod 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 differentPermissionCollectionobjects, even if they contain the same permissions.
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