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21
24 package org.lobobrowser.util;
25
26 import java.util.*;
27 import java.lang.ref.*;
28
29 public class WeakValueHashMap implements Map {
30 private final Map map = new HashMap();
31 private final ReferenceQueue queue = new ReferenceQueue();
32
33 public WeakValueHashMap() {
34 super();
35 }
36
37 public int size() {
38 return this.map.size();
39 }
40
41 public boolean isEmpty() {
42 return this.map.isEmpty();
43 }
44
45 public boolean containsKey(Object  key) {
46 WeakReference wf = (WeakReference) this.map.get(key);
47 return wf != null && wf.get() != null;
48 }
49
50 public boolean containsValue(Object value) {
51 throw new UnsupportedOperationException ();
52 }
53
54 public Object get(Object key) {
55 this.checkQueue();
56 WeakReference wf = (WeakReference) this.map.get(key);
57 return wf == null ? null : wf.get();
58 }
59
60 public Object put(Object key, Object value) {
61 if(value == null) {
62 throw new IllegalArgumentException ("null values not accepted");
63 }
64 this.checkQueue();
65 Reference ref = new LocalWeakReference(key, value, this.queue);
66 WeakReference oldWf = (WeakReference) this.map.put(key, ref);
67 return oldWf == null ? null : oldWf.get();
68 }
69
70 public Object remove(Object key) {
71 this.checkQueue();
72 WeakReference wf = (WeakReference) this.map.remove(key);
73 return wf == null ? null : wf.get();
74 }
75
76 public void putAll(Map t) {
77 this.checkQueue();
78 Iterator i = t.entrySet().iterator();
79 while(i.hasNext()) {
80 Map.Entry entry = (Map.Entry) i.next();
81 this.put(entry.getKey(), entry.getValue());
82 }
83 }
84
85 public void clear() {
86 this.checkQueue();
87 this.map.clear();
88 }
89
90 public Set keySet() {
91 return this.map.keySet();
92 }
93
94 private final void checkQueue() {
95 ReferenceQueue queue = this.queue;
96 LocalWeakReference ref;
97 while((ref = (LocalWeakReference) queue.poll()) != null) {
98 this.map.remove(ref.getKey());
99 }
100 }
101
102 public Collection values() {
103 return new FilteredCollection(this.map.values(), new LocalFilter());
104 }
105
106 public Set entrySet() {
107 throw new UnsupportedOperationException ();
108 }
109
110 private class LocalFilter implements ObjectFilter {
111
114 public Object decode(Object source) {
115 WeakReference wf = (WeakReference) source;
116 return wf == null ? null : wf.get();
117 }
118
119
122 public Object encode(Object source) {
123 throw new java.lang.UnsupportedOperationException ("Read-only collection.");
124 }
125 }
126
127 private static class LocalWeakReference extends WeakReference {
128 private final Object key;
129
130 public LocalWeakReference(Object key, Object target, ReferenceQueue queue) {
131 super(target, queue);
132 this.key = key;
133 }
134
135 public Object getKey() {
136 return key;
137 }
138
139 public boolean equals(Object other) {
140 Object target1 = this.get();
141 Object target2 = other instanceof LocalWeakReference ? ((LocalWeakReference) other).get() : null;
142 return Objects.equals(target1, target2);
143 }
144
145 public int hashCode() {
146 Object target = this.get();
147 return target == null ? 0 : target.hashCode();
148 }
149 }
150 }
151 |
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