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Java > Open Source Codes > org > apache > commons > betwixt > strategy > NamespacePrefixMapper


1 /*
2  * Copyright 2004 The Apache Software Foundation.
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16
17
18 package org.apache.commons.betwixt.strategy;
19
20 import java.util.HashMap JavaDoc;
21
22 /**
23  * <p>Maps namespace <code>URI</code>'s to prefixes.
24  * </p><p>
25  * When validating xml documents including namespaces,
26  * the issue of prefixes (the short expression before the colon in a universal name)
27  * becomes important.
28  * DTDs are not namespace aware and so a fixed prefixed must be chosen
29  * and used consistently.
30  * This class is used to supply consistent, user specified prefixes.
31  * </p><
32  * @author <a HREF='http://jakarta.apache.org/'>Jakarta Commons Team</a>
33  * @version $Revision: 1.2 $
34  */
35 public class NamespacePrefixMapper {
36     
37     private int count = 0;
38     private HashMap JavaDoc prefixesByUri = new HashMap JavaDoc();
39     
40     /**
41      * Gets the prefix to be used with the given namespace URI
42      * @param namespaceUri
43      * @return prefix, not null
44      */
45     public String JavaDoc getPrefix(String JavaDoc namespaceUri) {
46         String JavaDoc prefix = (String JavaDoc) prefixesByUri.get(namespaceUri);
47         if (prefix == null) {
48             prefix = generatePrefix(namespaceUri);
49             setPrefix(namespaceUri, prefix);
50         }
51         return prefix;
52     }
53     
54     /**
55      * Sets the prefix to be used for the given namespace URI.
56      * This method does not check for clashes amongst the namespaces.
57      * Possibly it should.
58      * @param namespaceUri
59      * @param prefix
60      */
61     public void setPrefix(String JavaDoc namespaceUri, String JavaDoc prefix) {
62         prefixesByUri.put(namespaceUri, prefix);
63     }
64     
65     /**
66      * Generates a prefix for the given namespace Uri.
67      * Used to assign prefixes for unassigned namespaces.
68      * Subclass may wish to override this method to provide more
69      * sophisticated implementations.
70      * @param namespaceUri URI, not null
71      * @return prefix, not null
72      */
73     protected String JavaDoc generatePrefix(String JavaDoc namespaceUri) {
74         String JavaDoc prefix = "bt" + ++count;
75         if (prefixesByUri.values().contains(prefix)) {
76             prefix = generatePrefix(namespaceUri);
77         }
78         return prefix;
79     }
80     
81 }
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