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Java > Open Source Codes > com > sun > org > apache > bcel > internal > verifier > VerifierFactory


1 package com.sun.org.apache.bcel.internal.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 JavaDoc;
58 import java.util.Iterator JavaDoc;
59 import java.util.Vector JavaDoc;
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 1.1.1.1 2001/10/29 20:00:32 jvanzyl Exp $
68  * @author <A HREF="http://www.inf.fu-berlin.de/~ehaase"/>Enver Haase</A>
69  */
70 public class VerifierFactory{
71
72     /**
73      * The HashMap that holds the data about the already-constructed Verifier instances.
74      */
75     private static HashMap JavaDoc hashMap = new HashMap JavaDoc();
76
77     /**
78      * The VerifierFactoryObserver instances that observe the VerifierFactory.
79      */
80     private static Vector JavaDoc observers = new Vector JavaDoc();
81
82     /**
83      * The VerifierFactory is not instantiable.
84      */
85     private VerifierFactory(){}
86     
87     /**
88      * Returns the (only) verifier responsible for the class with the given name.
89      * Possibly a new Verifier object is transparently created.
90      * @return the (only) verifier responsible for the class with the given name.
91      */
92     public static Verifier getVerifier(String JavaDoc fully_qualified_classname){
93         fully_qualified_classname = fully_qualified_classname;
94         
95         Verifier v = (Verifier) (hashMap.get(fully_qualified_classname));
96         if (v==null){
97             v = new Verifier(fully_qualified_classname);
98             hashMap.put(fully_qualified_classname, v);
99             notify(fully_qualified_classname);
100         }
101         
102         return v;
103     }
104
105     /**
106      * Notifies the observers of a newly generated Verifier.
107      */
108     private static void notify(String JavaDoc fully_qualified_classname){
109         // notify the observers
110 Iterator JavaDoc i = observers.iterator();
111         while (i.hasNext()){
112             VerifierFactoryObserver vfo = (VerifierFactoryObserver) i.next();
113             vfo.update(fully_qualified_classname);
114         }
115     }
116
117     /**
118      * Returns all Verifier instances created so far.
119      * This is useful when a Verifier recursively lets
120      * the VerifierFactory create other Verifier instances
121      * and if you want to verify the transitive hull of
122      * referenced class files.
123      */
124     public static Verifier[] getVerifiers(){
125         Verifier[] vs = new Verifier[hashMap.values().size()];
126         return (Verifier[]) (hashMap.values().toArray(vs)); // Because vs is big enough, vs is used to store the values into and returned!
127 }
128
129     /**
130      * Adds the VerifierFactoryObserver o to the list of observers.
131      */
132     public static void attach(VerifierFactoryObserver o){
133         observers.addElement(o);
134     }
135     
136     /**
137      * Removes the VerifierFactoryObserver o from the list of observers.
138      */
139     public static void detach(VerifierFactoryObserver o){
140             observers.removeElement(o);
141     }
142 }
143
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