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java.lang.Object | +--java.security.PermissionCollection | +--PkgAgentSystem.DynamicPermissions
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.
This collection allows also removing some or all permissions. This requires extensive modification to the security system, otherwise every thread could modify its own permissions and those of objects it holds a reference on.
Based on the java.security.Permissions
class.
Permission
,
PermissionCollection
,
AllPermission
, Serialized FormField Summary | |
protected PermissionCollection |
allPermission
Optimization. |
protected Hashtable |
perms
The contained permissions. |
Constructor Summary | |
DynamicPermissions()
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. |
(package private) DynamicPermissions |
copy()
Returns a copy of this object Package access for safety |
Enumeration |
elements()
Returns an enumeration of all the Permission objects in all the PermissionCollections in this Permissions object. |
protected PermissionCollection |
getPermissionCollection(Permission p)
Gets the PermissionCollection in this Permissions object for permissions whose type is the same as that of p. |
boolean |
implies(Permission permission)
Checks to see if this object's PermissionCollection for permissions of the specified permission's type implies the permissions expressed in the permission object. |
void |
remove(Permission permission)
Removes a permission object from the PermissionCollection for the class the permission belongs to. |
void |
removeAll()
Removes all permissions. |
void |
setReadOnly()
Sets this permission to read-only (Disabled here). |
Methods inherited from class java.security.PermissionCollection |
isReadOnly,
toString |
Methods inherited from class java.lang.Object |
|
Field Detail |
protected Hashtable perms
protected PermissionCollection allPermission
Constructor Detail |
public DynamicPermissions()
Method Detail |
public void setReadOnly()
public void add(Permission permission)
permission
- the Permission object to add.public void remove(Permission permission)
permission
- the public void removeAll()
public boolean implies(Permission 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.
permission
- the Permission object to check.public Enumeration elements()
protected PermissionCollection getPermissionCollection(Permission p)
newPermissionCollection
method
on p. Subclasses of class Permission
override that 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 the call returns a PermissionCollection, that collection is stored
in this Permissions object. If the call returns null, then
this method instantiates and stores a default PermissionCollection
that uses a hashtable to store its permission objects.DynamicPermissions copy()
Package access for safety
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