abstractpermission.java

这是一个基于角色的访问控制程序

/*
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
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 * 2. Redistributions in binary form must reproduce the above copyright
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * Portions of this software are based upon public domain software
 * originally written at the National Center for Supercomputing
 * Applications, University of Illinois, Urbana-Champaign.
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 */
package gov.nist.security.rbac;

import  java.io.*;
/**
 * A permission base class that provides generic implemenation with no internal data set.
 */
public class AbstractPermission implements IPermission, Serializable {
  /** Returns a null set of permission entry. */
  public IPermissionEntry[] getPermissionEntries() {
    return IPermissionEntry.ZERO_PERMISSION_ENTRY;
  }
  /** Returns a null set of role. */
  public IRole[] getAssignedRoles () {
    return  IRole.ZERO_ROLE;
  }
  /**
   * Returns true iff this permission is greater than or equal to
   * the given permission in terms of access privileges.
   */
  public boolean ge(IPermission p) {
    if (p == null) {
      return true;
    }
    if (p == this) {
      return true;
    }
    IPermissionEntry[] to_pe = p.getPermissionEntries();

    if (to_pe == null || to_pe.length == 0) {
      return true;
    }
    IPermissionEntry[] pe = getPermissionEntries();
  outter:
    for (int i=0; i < to_pe.length; i++) {
      IPermissionEntry pi = to_pe[i];
      for (int j=0; j < pe.length; j++) {
        IPermissionEntry pj = pe[j];
        if (pj.ge(pi)) {
          continue outter;
        }
      }
      return false;
    }
    return true;
  }
  /** Two permissions are equal if they have the same set of permission entries. */
  public boolean equals(Object o) {
    if (o == null || !(o instanceof IPermission)) {
      return false;
    }
    if (o == this) {
      return true;
    }
    IPermission p = (IPermission)o;
    IPermissionEntry[] pe = getPermissionEntries();
    IPermissionEntry[] to_pe = p.getPermissionEntries();

    if (pe == null && to_pe == null) {
      return true;
    }
    if (pe == null || to_pe == null) {
      return false;
    }
    if (pe.length != to_pe.length) {
      return false;
    }
  outter:
    for (int i=0; i < pe.length; i++) {
      IPermissionEntry pi = pe[i];
      for (int j=0; j < to_pe.length; j++) {
        IPermissionEntry pj = to_pe[j];
        if (pi.equals(pj)) {
          continue outter;
        }
      }
      return false;
    }
    return true;
  }
  public int hashCode() {
    IPermissionEntry[] pe = getPermissionEntries();
    int hashCode = 0;
    if (pe != null) {
      for (int i=0; i < pe.length; i++) {
        hashCode ^= pe[i].hashCode();
      }
    }
    return hashCode;
  }
  public String toString() {
    StringBuffer sb = new StringBuffer();
    IPermissionEntry[] p = getPermissionEntries();
    for (int i=0; i < p.length; i++) {
      sb.append("\n");
      sb.append(p[i].toString());
    }
    return sb.toString();
  }
}