Serializable
, Guard
AllPermission
, BasicPermission
, CardPermission
, FilePermission
, MBeanPermission
, PrivateCredentialPermission
, ServicePermission
, SocketPermission
, UnresolvedPermission
, URLPermission
public abstract class Permission extends Object implements Guard, Serializable
Most Permission
objects also include an "actions" list that tells the actions that are permitted for the object. For example, for a java.io.FilePermission
object, the permission name is the pathname of a file (or directory), and the actions list (such as "read, write") specifies which actions are granted for the specified file (or for files in the specified directory). The actions list is optional for Permission
objects, such as java.lang.RuntimePermission
, that don't need such a list; you either have the named permission (such as "system.exit") or you don't.
An important method that must be implemented by each subclass is the implies
method to compare Permissions. Basically, "permission p1 implies permission p2" means that if one is granted permission p1, one is naturally granted permission p2. Thus, this is not an equality test, but rather more of a subset test.
Permission
objects are similar to String
objects in that they are immutable once they have been created. Subclasses should not provide methods that can change the state of a permission once it has been created.
Constructor | Description |
---|---|
Permission |
Constructs a permission with the specified name. |
Modifier and Type | Method | Description |
---|---|---|
void |
checkGuard |
Implements the guard interface for a permission. |
abstract boolean |
equals |
Checks two Permission objects for equality. |
abstract String |
getActions() |
Returns the actions as a String . |
final String |
getName() |
Returns the name of this Permission . |
abstract int |
hashCode() |
Returns the hash code value for this Permission object. |
abstract boolean |
implies |
Checks if the specified permission's actions are "implied by" this object's actions. |
PermissionCollection |
newPermissionCollection() |
Returns an empty PermissionCollection for a given Permission object, or null if one is not defined. |
String |
toString() |
Returns a string describing this Permission . |
public Permission(String name)
name
- name of the Permission
object being created.public void checkGuard(Object object) throws SecurityException
SecurityManager.checkPermission
method is called, passing this permission object as the permission to check. Returns silently if access is granted. Otherwise, throws a SecurityException
.checkGuard
in interface Guard
object
- the object being guarded (currently ignored).SecurityException
- if a security manager exists and its checkPermission
method doesn't allow access.public abstract boolean implies(Permission permission)
This must be implemented by subclasses of Permission
, as they are the only ones that can impose semantics on a Permission
object.
The implies
method is used by the AccessController to determine whether a requested permission is implied by another permission that is known to be valid in the current execution context.
permission
- the permission to check against.true
if the specified permission is implied by this object, false
if not.public abstract boolean equals(Object obj)
Permission
objects for equality. Do not use the equals
method for making access control decisions; use the implies
method.
public abstract int hashCode()
Permission
object. The required hashCode
behavior for Permission
Objects is the following:
Permission
object more than once during an execution of a Java application, the hashCode
method must consistently return the same integer. This integer need not remain consistent from one execution of an application to another execution of the same application. Permission
objects are equal according to the equals
method, then calling the hashCode
method on each of the two Permission
objects must produce the same integer result. public final String getName()
Permission
. For example, in the case of a java.io.FilePermission
, the name will be a pathname.Permission
.public abstract String getActions()
String
. This is abstract so subclasses can defer creating a String
representation until one is needed. Subclasses should always return actions in what they consider to be their canonical form. For example, two FilePermission objects created via the following: perm1 = new FilePermission(p1,"read,write"); perm2 = new FilePermission(p2,"write,read");both return "read,write" when the
getActions
method is invoked.Permission
.public PermissionCollection newPermissionCollection()
PermissionCollection
for a given Permission
object, or null
if one is not defined. Subclasses of class Permission
should override this 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 null
is returned, then the caller of this method is free to store permissions of this type in any PermissionCollection
they choose (one that uses a Hashtable, one that uses a Vector, etc.).PermissionCollection
object for this type of Permission
, or null
if one is not defined.public String toString()
Permission
. The convention is to specify the class name, the permission name, and the actions in the following format: '("ClassName" "name" "actions")', or '("ClassName" "name")' if actions list is null
or empty.
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Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
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https://docs.oracle.com/en/java/javase/21/docs/api/java.base/java/security/Permission.html