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
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 and Description|
Constructs a permission with the specified name.
|Modifier and Type||Method and Description|
Checks two Permission objects for equality.
Returns the actions as a String.
Returns the name of this Permission.
Returns the hash code value for this Permission object.
Checks if the specified permission's actions are "implied by" this object's actions.
Returns a string describing this Permission.
public Permission(String name)
name- name of the Permission object being created.
public abstract boolean equals(@Nullable Object obj)
Do not use the
equals method for making access control decisions; use the
obj- the object we are testing for equality with this object.
public abstract String getActions()
perm1 = new FilePermission(p1, "read,write"); perm2 = new FilePermission(p2, "write,read");both return "read,write" when the
getActionsmethod is invoked.
public final String getName()
java.io.FilePermission, the name will be a pathname.
public abstract int hashCode()
hashCode behavior for Permission Objects is the following:
hashCodemethod 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.
equalsmethod, then calling the
hashCodemethod on each of the two Permission objects must produce the same integer result.
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.
permission- the permission to check against.
public String toString()