1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
|
package com.android.camera.gallery;
import java.lang.ref.WeakReference;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.Map;
public class LruCache<K, V> {
private final HashMap<K, V> mLruMap;
private final HashMap<K, WeakReference<V>> mWeakMap =
new HashMap<K, WeakReference<V>>();
//TODO: use ReferenceQueue to clean the cache
private final static int MAXIMUM_ADD_BEFORE_SWEEP = 128;
private int mAddBeforeSweep = 0;
public LruCache(final int capacity) {
mLruMap = new LinkedHashMap<K, V>(16, 0.75f, true) {
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
return size() > capacity;
}
};
}
public synchronized V put(K key, V value) {
if (++mAddBeforeSweep > MAXIMUM_ADD_BEFORE_SWEEP) {
mAddBeforeSweep = 0;
Iterator<Map.Entry<K, WeakReference<V>>> iter =
mWeakMap.entrySet().iterator();
while (iter.hasNext()) {
Map.Entry<K, WeakReference<V>> entry = iter.next();
if (entry.getValue().get() == null) iter.remove();
}
}
mLruMap.put(key, value);
WeakReference<V> ref = mWeakMap.put(key, new WeakReference<V>(value));
return ref == null ? null : ref.get();
}
public synchronized V get(K key) {
V value = mLruMap.get(key);
if (value != null) return value;
WeakReference<V> ref = mWeakMap.get(key);
value = ref == null ? null : ref.get();
if (value == null && ref != null) {
mWeakMap.remove(key);
}
return value;
}
public synchronized void clear() {
mLruMap.clear();
mWeakMap.clear();
}
}
|
