JavaTM 2 Platform Std. Ed. v1.6.0
java.security
Class Permissions
java.lang.Object
java.security.PermissionCollection
java.security.Permissions
- All Implemented Interfaces:
- Serializable
public final class Permissions - extends PermissionCollection
- implements Serializable
This class represents a heterogeneous collection of Permissions. That is,
it contains different types of Permission objects, organized into
PermissionCollections. For example, if any
java.io.FilePermission objects are added to an instance of
this class, they are all stored in a single
PermissionCollection. It is the PermissionCollection returned by a call to
the newPermissionCollection method in the FilePermission class.
Similarly, any java.lang.RuntimePermission objects are
stored in the PermissionCollection returned by a call to the
newPermissionCollection method in the
RuntimePermission class. Thus, this class represents a collection of
PermissionCollections.
When the add method is called to add a Permission, the
Permission is stored in the appropriate PermissionCollection. If no such
collection exists yet, the Permission object's class is determined and the
newPermissionCollection method is called on that class to create
the PermissionCollection and add it to the Permissions object. If
newPermissionCollection returns null, then a default
PermissionCollection that uses a hashtable will be created and used. Each
hashtable entry stores a Permission object as both the key and the value.
Enumerations returned via the elements method are
not fail-fast. Modifications to a collection should not be
performed while enumerating over that collection.
- See Also:
Permission ,
PermissionCollection ,
AllPermission
Constructor Summary |
Permissions()
Creates a new Permissions object containing no PermissionCollections. |
Method Summary |
void |
add(Permission permission)
Adds a permission object to the PermissionCollection for the class the
permission belongs to. |
Enumeration<Permission> |
elements()
Returns an enumeration of all the Permission objects in all the
PermissionCollections in this Permissions object. |
boolean |
implies(Permission permission)
Checks to see if this object's PermissionCollection for permissions of
the specified permission's class implies the permissions
expressed in the permission object. |
Permissions
public Permissions()
- Creates a new Permissions object containing no PermissionCollections.
add
public void add(Permission permission)
- Adds a permission object to the PermissionCollection for the class the
permission belongs to. For example, if permission is a
FilePermission, it is added to the FilePermissionCollection stored
in this Permissions object.
This method creates
a new PermissionCollection object (and adds the permission to it)
if an appropriate collection does not yet exist.
- Specified by:
add in class PermissionCollection
- Parameters:
permission - the Permission object to add.
- Throws:
SecurityException - if this Permissions object is
marked as readonly.- See Also:
PermissionCollection.isReadOnly()
implies
public boolean implies(Permission permission)
- Checks to see if this object's PermissionCollection for permissions of
the specified permission's class implies the permissions
expressed in the permission object. Returns true if the
combination of permissions in the appropriate PermissionCollection
(e.g., a FilePermissionCollection for a FilePermission) together
imply the specified permission.
For example, suppose there is a FilePermissionCollection in this
Permissions object, and it contains one FilePermission that specifies
"read" access for all files in all subdirectories of the "/tmp"
directory, and another FilePermission that specifies "write" access
for all files in the "/tmp/scratch/foo" directory.
Then if the implies method
is called with a permission specifying both "read" and "write" access
to files in the "/tmp/scratch/foo" directory, true is
returned.
Additionally, if this PermissionCollection contains the
AllPermission, this method will always return true.
- Specified by:
implies in class PermissionCollection
- Parameters:
permission - the Permission object to check.
- Returns:
- true if "permission" is implied by the permissions in the
PermissionCollection it
belongs to, false if not.
elements
public Enumeration<Permission> elements()
- Returns an enumeration of all the Permission objects in all the
PermissionCollections in this Permissions object.
- Specified by:
elements in class PermissionCollection
- Returns:
- an enumeration of all the Permissions.
Copyright 2003 Sun Microsystems, Inc. All rights reserved
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