84 lines
1.8 KiB
Plaintext
84 lines
1.8 KiB
Plaintext
package com.novelbook.android.utils;
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import java.util.LinkedHashMap;
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import java.util.Map;
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/**
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* 按照插入顺序排序的Map，当超出容量时，将最早插入的对象移除。
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*
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* @param <K>
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* @param <V>
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*/
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public class FIFOMap<K, V> extends LinkedHashMap<K, V> {
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private static final long serialVersionUID = 27034646516234314L;
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protected int maxSize;
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public FIFOMap(int maxSize) {
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super(maxSize, 0.75f, false);
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this.maxSize = maxSize;
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}
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@Override
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protected boolean removeEldestEntry(Entry<K, V> eldest) {
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return maxSize < size();
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}
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@Override
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public synchronized V put(K key, V value) {
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return super.put(key, value);
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}
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@Override
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public synchronized void putAll(Map<? extends K, ? extends V> m) {
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super.putAll(m);
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}
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@Override
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public synchronized V remove(Object key) {
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return super.remove(key);
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}
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public void setCapacity(int size) {
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maxSize = size;
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}
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public int getCapacity() {
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return maxSize;
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}
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public static void main(String[] args) {
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int maxSize = 100;
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FIFOMap<Integer, Integer> map = new FIFOMap<Integer, Integer>(maxSize);
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for (int i = 1; i <= maxSize; i++) {
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map.put(i, i);
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assertTrue(map.size() == i);
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}
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for (int i = 1; i <= maxSize; i++) {
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map.put(i, i);
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assertTrue(map.size() == maxSize);
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}
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for (int i = 101; i <= 100 + maxSize; i++) {
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map.put(i, i);
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assertTrue(map.size() == maxSize);
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}
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for (int i = 191; i <= 100 + maxSize; i++) {
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map.remove(i);
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assertTrue(map.size()== maxSize + 190 - i );
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}
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for (int i = 101; i <= 100 + maxSize; i++) {
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map.put(i, i);
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}
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for (int i = 1; i <= 10000 + maxSize; i++) {
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map.put(i, i);
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}
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assertTrue(map.size() == maxSize);
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}
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private static void assertTrue(boolean flag) {
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if ( !flag ) System.out.println("should be true. but is false.");
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}
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}
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