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1
7
8 package org.dom4j.tree;
9
10 import java.lang.ref.WeakReference  ;
11 import java.lang.reflect.Constructor ;
12 import java.util.Map ;
13
14 import org.dom4j.Namespace;
15
16
28 public class NamespaceCache {
29 private static final String CONCURRENTREADERHASHMAP_CLASS
30 = "EDU.oswego.cs.dl.util.concurrent.ConcurrentReaderHashMap";
31
32
36 protected static Map cache;
37
38
42 protected static Map noPrefixCache;
43
44 static {
45
46 try {
47 Class clazz = Class
48 .forName("java.util.concurrent.ConcurrentHashMap");
49 Constructor construct = clazz.getConstructor(new Class [] {
50 Integer.TYPE, Float.TYPE, Integer.TYPE });
51 cache = (Map ) construct.newInstance(new Object [] {new Integer (11),
52 new Float (0.75f), new Integer (1) });
53 noPrefixCache = (Map ) construct.newInstance(new Object [] {
54 new Integer (11), new Float (0.75f), new Integer (1) });
55 } catch (Throwable t1) {
56
57 try {
58 Class clazz = Class.forName(CONCURRENTREADERHASHMAP_CLASS);
59 cache = (Map ) clazz.newInstance();
60 noPrefixCache = (Map ) clazz.newInstance();
61 } catch (Throwable t2) {
62
63 cache = new ConcurrentReaderHashMap();
64 noPrefixCache = new ConcurrentReaderHashMap();
65 }
66 }
67 }
68
69
79 public Namespace get(String prefix, String uri) {
80 Map uriCache = getURICache(uri);
81 WeakReference ref = (WeakReference ) uriCache.get(prefix);
82 Namespace answer = null;
83
84 if (ref != null) {
85 answer = (Namespace) ref.get();
86 }
87
88 if (answer == null) {
89 synchronized (uriCache) {
90 ref = (WeakReference ) uriCache.get(prefix);
91
92 if (ref != null) {
93 answer = (Namespace) ref.get();
94 }
95
96 if (answer == null) {
97 answer = createNamespace(prefix, uri);
98 uriCache.put(prefix, new WeakReference (answer));
99 }
100 }
101 }
102
103 return answer;
104 }
105
106
114 public Namespace get(String uri) {
115 WeakReference ref = (WeakReference ) noPrefixCache.get(uri);
116 Namespace answer = null;
117
118 if (ref != null) {
119 answer = (Namespace) ref.get();
120 }
121
122 if (answer == null) {
123 synchronized (noPrefixCache) {
124 ref = (WeakReference ) noPrefixCache.get(uri);
125
126 if (ref != null) {
127 answer = (Namespace) ref.get();
128 }
129
130 if (answer == null) {
131 answer = createNamespace("", uri);
132 noPrefixCache.put(uri, new WeakReference (answer));
133 }
134 }
135 }
136
137 return answer;
138 }
139
140
149 protected Map getURICache(String uri) {
150 Map answer = (Map ) cache.get(uri);
151
152 if (answer == null) {
153 synchronized (cache) {
154 answer = (Map ) cache.get(uri);
155
156 if (answer == null) {
157 answer = new ConcurrentReaderHashMap();
158 cache.put(uri, answer);
159 }
160 }
161 }
162
163 return answer;
164 }
165
166
176 protected Namespace createNamespace(String prefix, String uri) {
177 return new Namespace(prefix, uri);
178 }
179 }
180
181
217 |
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