java.security.PermissionCollection Maven / Gradle / Ivy

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This work corresponds to the API signatures of JSR 219: Foundation Profile 1.1. In the event of a discrepency between this work and the JSR 219 specification, which is available at http://www.jcp.org/en/jsr/detail?id=219, the latter takes precedence. */ package java.security; import java.util.*; /** * Abstract class representing a collection of Permission objects. * *

With a PermissionCollection, you can: *

*
• add a permission to the collection using the add method. *
• check to see if a particular permission is implied in the * collection, using the implies method. *
• enumerate all the permissions, using the elements method. *

* *

When it is desirable to group together a number of Permission objects * of the same type, the newPermissionCollection method on that * particular type of Permission object should first be called. The default * behavior (from the Permission class) is to simply return null. * Subclasses of class Permission override the 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 a non-null value is returned, that PermissionCollection must be used. * If null is returned, then the caller of newPermissionCollection * is free to store permissions of the * given type in any PermissionCollection they choose * (one that uses a Hashtable, one that uses a Vector, etc). * *

The PermissionCollection returned by the * Permission.newPermissionCollection * method is a homogeneous collection, which stores only Permission objects * for a given Permission type. A PermissionCollection may also be * heterogenous. For example, Permissions is a PermissionCollection * subclass that represents a collection of PermissionCollections. * That is, its members are each a homogeneous PermissionCollection. * For example, a Permissions object might have a FilePermissionCollection * for all the FilePermission objects, a SocketPermissionCollection for all the * SocketPermission objects, and so on. Its add method adds a * permission to the appropriate collection. * *

Whenever a permission is added to a heterogeneous PermissionCollection * such as Permissions, and the PermissionCollection doesn't yet contain a * PermissionCollection of the specified permission's type, the * PermissionCollection should call * the newPermissionCollection method on the permission's class * to see if it requires a special PermissionCollection. If * newPermissionCollection * returns null, the PermissionCollection * is free to store the permission in any type of PermissionCollection it * desires (one using a Hastable, one using a Vector, etc.). For example, * the Permissions object uses a default PermissionCollection implementation * that stores the permission objects in a Hashtable. * *

Subclass implementations of PermissionCollection should assume * that they may be called simultaneously from multiple threads, * and therefore should be synchronized properly. Furthermore, * Enumerations returned via the elements method are * not fail-fast. Modifications to a collection should not be * performed while enumerating over that collection. * * @see Permission * @see Permissions * * @version 1.26 00/02/02 * * @author Roland Schemers */ public abstract class PermissionCollection implements java.io.Serializable { private boolean readOnly; private static final long serialVersionUID = -6727011328946861783L; public PermissionCollection() { } /** * Adds a permission object to the current collection of permission objects. * * @param permission the Permission object to add. * * @exception SecurityException - if this PermissionCollection object * has been marked readonly */ public abstract void add(Permission permission); /** * Checks to see if the specified permission is implied by * the collection of Permission objects held in this PermissionCollection. * * @param permission the Permission object to compare. * * @return true if "permission" is implied by the permissions in * the collection, false if not. */ public abstract boolean implies(Permission permission); /** * Returns an enumeration of all the Permission objects in the collection. * * @return an enumeration of all the Permissions. */ public abstract Enumeration elements(); /** * Marks this PermissionCollection object as "readonly". After * a PermissionCollection object * is marked as readonly, no new Permission objects can be added to it * using add. */ public void setReadOnly() { } /** * Returns true if this PermissionCollection object is marked as readonly. * If it is readonly, no new Permission objects can be added to it * using add. * *

By default, the object is not readonly. It can be set to * readonly by a call to setReadOnly. * * @return true if this PermissionCollection object is marked as readonly, * false otherwise. */ public boolean isReadOnly() { return false; } /** * Returns a string describing this PermissionCollection object, * providing information about all the permissions it contains. * The format is: *

     * super.toString() (
     *   // enumerate all the Permission
     *   // objects and call toString() on them,
     *   // one per line..
     * )