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1: /* PermissionCollection.java -- A collection of permission objects 2: Copyright (C) 1998, 2001, 2002, 2005 Free Software Foundation, Inc. 3: 4: This file is part of GNU Classpath. 5: 6: GNU Classpath is free software; you can redistribute it and/or modify 7: it under the terms of the GNU General Public License as published by 8: the Free Software Foundation; either version 2, or (at your option) 9: any later version. 10: 11: GNU Classpath is distributed in the hope that it will be useful, but 12: WITHOUT ANY WARRANTY; without even the implied warranty of 13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14: General Public License for more details. 15: 16: You should have received a copy of the GNU General Public License 17: along with GNU Classpath; see the file COPYING. If not, write to the 18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19: 02110-1301 USA. 20: 21: Linking this library statically or dynamically with other modules is 22: making a combined work based on this library. Thus, the terms and 23: conditions of the GNU General Public License cover the whole 24: combination. 25: 26: As a special exception, the copyright holders of this library give you 27: permission to link this library with independent modules to produce an 28: executable, regardless of the license terms of these independent 29: modules, and to copy and distribute the resulting executable under 30: terms of your choice, provided that you also meet, for each linked 31: independent module, the terms and conditions of the license of that 32: module. An independent module is a module which is not derived from 33: or based on this library. If you modify this library, you may extend 34: this exception to your version of the library, but you are not 35: obligated to do so. If you do not wish to do so, delete this 36: exception statement from your version. */ 37: 38: package java.security; 39: 40: import gnu.java.lang.CPStringBuilder; 41: 42: import java.io.Serializable; 43: import java.util.Enumeration; 44: 45: /** 46: * This class models a group of Java permissions. It has convenient 47: * methods for determining whether or not a given permission is implied 48: * by any of the permissions in this collection. 49: * 50: * <p>Some care must be taken in storing permissions. First, a collection of 51: * the appropriate type must be created. This is done by calling the 52: * <code>newPermissionCollection</code> method on an object of the 53: * permission class you wish to add to the collection. If this method 54: * returns <code>null</code>, any type of <code>PermissionCollection</code> 55: * can be used to store permissions of that type. However, if a 56: * <code>PermissionCollection</code> collection object is returned, that 57: * type must be used. 58: * 59: * <p>A <code>PermissionCollection</code> returned by the 60: * <code>newPermissionCollection</code> method in a subclass of 61: * <code>Permission</code> is a homogeneous collection. It only will 62: * hold permissions of one specified type - instances of the class that 63: * created it. Not all <code>PermissionCollection</code> subclasses 64: * have to hold permissions of only one type however. For example, 65: * the <code>Permissions</code> class holds permissions of many types. 66: * 67: * <p>Since the <code>newPermissionCollection</code> in <code>Permission</code> 68: * itself returns <code>null</code>, by default a permission can be stored 69: * in any type of collection unless it overrides that method to create its 70: * own collection type. 71: * 72: * @author Aaron M. Renn (arenn@urbanophile.com) 73: * @author Eric Blake (ebb9@email.byu.edu) 74: * @see Permission 75: * @see Permissions 76: * @since 1.1 77: * @status updated to 1.4 78: */ 79: public abstract class PermissionCollection implements Serializable 80: { 81: /** 82: * Compatible with JDK 1.1+. 83: */ 84: private static final long serialVersionUID = -6727011328946861783L; 85: 86: /** 87: * Indicates whether or not this collection is read only. 88: * 89: * @serial if the collection is read-only 90: */ 91: private boolean readOnly; 92: 93: /** 94: * Create a new collection. 95: */ 96: public PermissionCollection() 97: { 98: } 99: 100: /** 101: * This method adds a new <code>Permission</code> object to the collection. 102: * 103: * @param perm the <code>Permission</code> to add 104: * 105: * @throws SecurityException if the collection is marked read only 106: * @throws IllegalArgumentException if perm is of the wrong type 107: */ 108: public abstract void add(Permission perm); 109: 110: /** 111: * This method tests whether the specified <code>Permission</code> object is 112: * implied by this collection of <code>Permission</code> objects. 113: * 114: * @param perm the <code>Permission</code> object to test 115: * @return true if the collection implies perm 116: */ 117: public abstract boolean implies(Permission perm); 118: 119: /** 120: * This method returns an <code>Enumeration</code> of all the objects in 121: * this collection. 122: * 123: * @return an <code>Enumeration</code> of this collection's objects 124: */ 125: public abstract Enumeration<Permission> elements(); 126: 127: /** 128: * This method sets this <code>PermissionCollection</code> object to be 129: * read only. No further permissions can be added to it after calling this 130: * method. 131: */ 132: public void setReadOnly() 133: { 134: readOnly = true; 135: } 136: 137: /** 138: * This method tests whether or not this <code>PermissionCollection</code> 139: * object is read only. 140: * 141: * @return true if this collection is read only 142: */ 143: public boolean isReadOnly() 144: { 145: return readOnly; 146: } 147: 148: /** 149: * This method returns a <code>String</code> representation of this 150: * collection. It is formed by: 151: * <pre> 152: * super.toString()" (\n" 153: * // enumerate all permissions, one per line 154: * ")\n" 155: * </pre> 156: * 157: * @return a <code>String</code> representing this object 158: */ 159: public String toString() 160: { 161: CPStringBuilder sb = new CPStringBuilder(super.toString()); 162: 163: sb.append(" (\n"); 164: Enumeration<Permission> e = elements(); 165: while (e.hasMoreElements()) 166: sb.append(' ').append(e.nextElement()).append('\n'); 167: return sb.append(")\n").toString(); 168: } 169: } // class PermissionCollection