1 /*
   2  * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
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  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.security;
  27 
  28 import javax.security.auth.Subject;
  29 
  30 /**
  31  * This interface represents the abstract notion of a principal, which
  32  * can be used to represent any entity, such as an individual, a
  33  * corporation, and a login id.
  34  *
  35  * @see java.security.cert.X509Certificate
  36  *
  37  * @author Li Gong
  38  */
  39 public interface Principal {
  40 
  41     /**
  42      * Compares this principal to the specified object.  Returns true
  43      * if the object passed in matches the principal represented by
  44      * the implementation of this interface.
  45      *
  46      * @param another principal to compare with.
  47      *
  48      * @return true if the principal passed in is the same as that
  49      * encapsulated by this principal, and false otherwise.
  50      */
  51     public boolean equals(Object another);
  52 
  53     /**
  54      * Returns a string representation of this principal.
  55      *
  56      * @return a string representation of this principal.
  57      */
  58     public String toString();
  59 
  60     /**
  61      * Returns a hashcode for this principal.
  62      *
  63      * @return a hashcode for this principal.
  64      */
  65     public int hashCode();
  66 
  67     /**
  68      * Returns the name of this principal.
  69      *
  70      * @return the name of this principal.
  71      */
  72     public String getName();
  73 
  74     /**
  75      * Returns true if the specified subject is implied by this principal.
  76      *
  77      * @implSpec
  78      * The default implementation of this method returns true if
  79      * {@code subject} is non-null and contains at least one principal that
  80      * is equal to this principal.
  81      *
  82      * <p>Subclasses may override this with a different implementation, if
  83      * necessary.
  84      *
  85      * @param subject the {@code Subject}
  86      * @return true if {@code subject} is non-null and is
  87      *              implied by this principal, or false otherwise.
  88      * @since 1.8
  89      */
  90     public default boolean implies(Subject subject) {
  91         if (subject == null)
  92             return false;
  93         return subject.getPrincipals().contains(this);
  94     }
  95 }