java.security
Class Permission
java.lang.Object
|
+--java.security.Permission
All Implemented Interfaces:
Guard, Serializable
This class is the abstract superclass of all classes that implement
the concept of a permission. A permission consists of a permission name
and optionally a list of actions that relate to the permission. The
actual meaning of the name of the permission is defined only in the
context of a subclass. It may name a resource to which access permissions
are granted (for example, the name of a file) or it might represent
something else entirely. Similarly, the action list only has meaning
within the context of a subclass. Some permission names may have no
actions associated with them. That is, you either have the permission
or you don't.
The most important method in this class is implies
. This
checks whether if one has this permission, then the specified
permission is also implied. As a conceptual example, consider the
permissions "Read All Files" and "Read File foo". The permission
"Read All Files" implies that the caller has permission to read the
file foo.
Permission
's must be immutable - do not change their
state after creation.
Since:Author:- Aaron M. Renn <arenn@urbanophile.com>
See Also:
Permission
public Permission(java.lang.String name)
Create an instance with the specified name.
Parameters:
checkGuard
public void checkGuard(java.lang.Object obj)
This method implements the Guard
interface for this class.
It calls the checkPermission
method in
SecurityManager
with this Permission
as its
argument. This method returns silently if the security check succeeds
or throws an exception if it fails.
Parameters:
Throws:
See Also:
equals
public boolean equals(java.lang.Object obj)
Check to see if this object equals obj. Use implies
, rather
than equals
, when making access control decisions.
Parameters:
getActions
public String getActions()
This method returns the list of actions for this Permission
as a String
. The string should be in canonical order, for
example, both new FilePermission(f, "write,read")
and
new FilePermission(f, "read,write")
have the action list
"read,write".
Returns:
- the action list for this
Permission
getName
public final String getName()
Get the name of this Permission
.
Returns:
hashCode
public int hashCode()
This method returns a hash code for this Permission
. It
must satisfy the contract of Object.hashCode
: it must be
the same for all objects that equals considers to be the same.
Returns:
implies
public boolean implies(java.security.Permission perm)
This method tests whether this Permission
implies that the
specified Permission
is also granted.
Parameters:
Returns:
- true if perm is implied by this
newPermissionCollection
public PermissionCollection newPermissionCollection()
This method returns an empty PermissionCollection
object
that can store permissions of this type, or null
if no
such collection is defined. Subclasses must override this to provide
an appropriate collection when one is needed to accurately calculate
implies
.
Returns:
- a new
PermissionCollection
toString
public String toString()
This method returns a String
representation of this
Permission
object. This is in the format:
'(' + getClass().getName() + ' ' + getName() + ' ' + getActions
+ ')'
.
Returns:
The most important method in this class is
implies
. This checks whether if one has this permission, then the specified permission is also implied. As a conceptual example, consider the permissions "Read All Files" and "Read File foo". The permission "Read All Files" implies that the caller has permission to read the file foo.Permission
's must be immutable - do not change their state after creation.