1 package org.apache.bcel.verifier;
2
3 /* ====================================================================
4 * The Apache Software License, Version 1.1
5 *
6 * Copyright (c) 2001 The Apache Software Foundation. All rights
7 * reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 *
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 *
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in
18 * the documentation and/or other materials provided with the
19 * distribution.
20 *
21 * 3. The end-user documentation included with the redistribution,
22 * if any, must include the following acknowledgment:
23 * "This product includes software developed by the
24 * Apache Software Foundation (http://www.apache.org/)."
25 * Alternately, this acknowledgment may appear in the software itself,
26 * if and wherever such third-party acknowledgments normally appear.
27 *
28 * 4. The names "Apache" and "Apache Software Foundation" and
29 * "Apache BCEL" must not be used to endorse or promote products
30 * derived from this software without prior written permission. For
31 * written permission, please contact apache@apache.org.
32 *
33 * 5. Products derived from this software may not be called "Apache",
34 * "Apache BCEL", nor may "Apache" appear in their name, without
35 * prior written permission of the Apache Software Foundation.
36 *
37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
48 * SUCH DAMAGE.
49 * ====================================================================
50 *
51 * This software consists of voluntary contributions made by many
52 * individuals on behalf of the Apache Software Foundation. For more
53 * information on the Apache Software Foundation, please see
54 * <http://www.apache.org/>.
55 */
56
57 import java.util.HashMap;
58 import java.util.Iterator;
59 import java.util.Vector;
60
61 /***
62 * This class produces instances of the Verifier class. Its purpose is to make
63 * sure that they are singleton instances with respect to the class name they
64 * operate on. That means, for every class (represented by a unique fully qualified
65 * class name) there is exactly one Verifier.
66 *
67 * @version $Id: VerifierFactory.java,v 1.2 2002/02/07 23:22:30 enver Exp $
68 * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
69 * @see org.apache.bcel.verifier.Verifier
70 */
71 public class VerifierFactory{
72
73 /***
74 * The HashMap that holds the data about the already-constructed Verifier instances.
75 */
76 private static HashMap hashMap = new HashMap();
77
78 /***
79 * The VerifierFactoryObserver instances that observe the VerifierFactory.
80 */
81 private static Vector observers = new Vector();
82
83 /***
84 * The VerifierFactory is not instantiable.
85 */
86 private VerifierFactory(){}
87
88 /***
89 * Returns the (only) verifier responsible for the class with the given name.
90 * Possibly a new Verifier object is transparently created.
91 * @return the (only) verifier responsible for the class with the given name.
92 */
93 public static Verifier getVerifier(String fully_qualified_classname){
94 fully_qualified_classname = fully_qualified_classname;
95
96 Verifier v = (Verifier) (hashMap.get(fully_qualified_classname));
97 if (v==null){
98 v = new Verifier(fully_qualified_classname);
99 hashMap.put(fully_qualified_classname, v);
100 notify(fully_qualified_classname);
101 }
102
103 return v;
104 }
105
106 /***
107 * Notifies the observers of a newly generated Verifier.
108 */
109 private static void notify(String fully_qualified_classname){
110 // notify the observers
111 Iterator i = observers.iterator();
112 while (i.hasNext()){
113 VerifierFactoryObserver vfo = (VerifierFactoryObserver) i.next();
114 vfo.update(fully_qualified_classname);
115 }
116 }
117
118 /***
119 * Returns all Verifier instances created so far.
120 * This is useful when a Verifier recursively lets
121 * the VerifierFactory create other Verifier instances
122 * and if you want to verify the transitive hull of
123 * referenced class files.
124 */
125 public static Verifier[] getVerifiers(){
126 Verifier[] vs = new Verifier[hashMap.values().size()];
127 return (Verifier[]) (hashMap.values().toArray(vs)); // Because vs is big enough, vs is used to store the values into and returned!
128 }
129
130 /***
131 * Adds the VerifierFactoryObserver o to the list of observers.
132 */
133 public static void attach(VerifierFactoryObserver o){
134 observers.addElement(o);
135 }
136
137 /***
138 * Removes the VerifierFactoryObserver o from the list of observers.
139 */
140 public static void detach(VerifierFactoryObserver o){
141 observers.removeElement(o);
142 }
143 }
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