Permission (GNU Classpath 0.94-pre Documentation)

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: 1.1

UNKNOWN: updated to 1.4

Constructor Summary
	Permission(String name) Create an instance with the specified name.

Method Summary
void	checkGuard(Object obj) This method implements the `Guard` interface for this class.
abstract boolean	equals(Object obj) Check to see if this object equals obj.
abstract String	getActions() This method returns the list of actions for this `Permission` as a `String`.
String	getName() Get the name of this `Permission`.
abstract int	hashCode() This method returns a hash code for this `Permission`.
abstract boolean	implies(Permission perm) This method tests whether this `Permission` implies that the specified `Permission` is also granted.
PermissionCollection	newPermissionCollection() This method returns an empty `PermissionCollection` object that can store permissions of this type, or `null` if no such collection is defined.
String	toString() This method returns a `String` representation of this `Permission` object.

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: obj the Object being guarded - ignored by this class

Throws: SecurityException if the security check fails

See Also: GuardedObject checkPermission

equals

Check to see if this object equals obj. Use implies, rather than equals, when making access control decisions.

Parameters: obj the object to compare to

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

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: a hash value

implies

This method tests whether this Permission implies that the specified Permission is also granted.

Parameters: perm the Permission to test against

Returns: true if perm is implied by this

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

This method returns a String representation of this Permission object. This is in the format:

'(' + getClass().getName() + ' ' + getName() + ' ' + getActions
 + ')'

Returns: this object as a String

Class Permission