/* * Copyright (c) 1997, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.security; import java.util.*; /** * Abstract class representing a collection of Permission objects. * *
With a PermissionCollection, you can: *
add
method.
* implies
method.
* 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 PermissionCollection 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 PermissionCollections.
* That is, its members are each a homogeneous PermissionCollection.
* For example, a Permissions 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 By default, the object is not readonly. It can be set to
* readonly by a call to elements
method are
* not fail-fast. Modifications to a collection should not be
* performed while enumerating over that collection.
*
* @see Permission
* @see Permissions
*
*
* @author Roland Schemers
*/
public abstract class PermissionCollection implements java.io.Serializable {
private static final long serialVersionUID = -6727011328946861783L;
// when set, add will throw an exception.
private volatile boolean readOnly;
/**
* Adds a permission object to the current collection of permission objects.
*
* @param permission the Permission object to add.
*
* @exception SecurityException - if this PermissionCollection object
* has been marked readonly
* @exception IllegalArgumentException - if this PermissionCollection
* object is a homogeneous collection and the permission
* is not of the correct type.
*/
public abstract void add(Permission permission);
/**
* Checks to see if the specified permission is implied by
* the collection of Permission objects held in this PermissionCollection.
*
* @param permission the Permission object to compare.
*
* @return true if "permission" is implied by the permissions in
* the collection, false if not.
*/
public abstract boolean implies(Permission permission);
/**
* Returns an enumeration of all the Permission objects in the collection.
*
* @return an enumeration of all the Permissions.
*/
public abstract Enumerationadd
.
*/
public void setReadOnly() {
readOnly = true;
}
/**
* Returns true if this PermissionCollection object is marked as readonly.
* If it is readonly, no new Permission objects can be added to it
* using add
.
*
* setReadOnly
.
*
* @return true if this PermissionCollection object is marked as readonly,
* false otherwise.
*/
public boolean isReadOnly() {
return readOnly;
}
/**
* Returns a string describing this PermissionCollection 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 the toString
* method of this
* object's superclass, which is Object. The result is
* this PermissionCollection's type name followed by this object's
* hashcode, thus enabling clients to differentiate different
* PermissionCollections object, even if they contain the same permissions.
*
* @return information about this PermissionCollection object,
* as described above.
*
*/
public String toString() {
Enumeration