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Commit bf00483

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LRU实现
1 parent bb24570 commit bf00483

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4 files changed

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4 files changed

+201
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‎lru/pom.xml‎

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<?xml version="1.0" encoding="UTF-8"?>
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<project xmlns="http://maven.apache.org/POM/4.0.0"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
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<parent>
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<artifactId>algorithm-study</artifactId>
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<groupId>com.mistray</groupId>
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<version>1.0-SNAPSHOT</version>
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</parent>
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<modelVersion>4.0.0</modelVersion>
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<artifactId>lru</artifactId>
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</project>
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package com.mistray;
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import java.util.LinkedHashMap;
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import java.util.Map;
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/**
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* 实现了LRU的LinkedHashMap
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*
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* @author ZJY(MistRay)
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* @Project algorithm-study
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* @Package com.mistray
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* @create 2019年10月14日 20:24
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* @Desc LRU
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*/
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public class LRULinkedHashMap<K, V> extends LinkedHashMap<K, V> {
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/**
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* 建议数值 2^n-1(3 7 15 31...)
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*/
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private final int maxCapacity;
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private static final float DEFAULT_LOAD_FACTOR = 1f;
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public LRULinkedHashMap(int maxCapacity) {
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super(maxCapacity + 1, DEFAULT_LOAD_FACTOR, true);
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this.maxCapacity = maxCapacity;
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}
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@Override
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protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
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return size() > maxCapacity;
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}
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}
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/**
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* Copyright © FEITIAN Technologies Co., Ltd. All Rights Reserved.
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*
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* @Date 2019年2月22日, 上午10:35:35
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*/
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package com.mistray;
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import java.util.Collection;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.locks.Lock;
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import java.util.concurrent.locks.ReadWriteLock;
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import java.util.concurrent.locks.ReentrantReadWriteLock;
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/**
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* 包装持有读写锁的map
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*
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* @author ZJY(MistRay)
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* @Project algorithm-study
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* @Package com.mistray
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* @create 2019年10月14日 20:24
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* @Desc 读写锁
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*/
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public class ReadWriteMapWrapFactory {
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public static <K, V> Map<K, V> readWriteMap(Map<K, V> m) {
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return new ReadWriteMap<K, V>(m);
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}
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private static class ReadWriteMap<K, V> implements Map<K, V> {
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private final Map<K, V> map;
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private final ReadWriteLock lock = new ReentrantReadWriteLock();
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private final Lock r = lock.readLock();
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private final Lock w = lock.writeLock();
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public ReadWriteMap(Map<K, V> map) {
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this.map = map;
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}
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public V put(K key, V value) {
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w.lock();
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try {
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return map.put(key, value);
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} finally {
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w.unlock();
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}
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}
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public V get(Object key) {
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r.lock();
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try {
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return map.get(key);
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} finally {
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r.unlock();
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}
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}
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public int size() {
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r.lock();
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try {
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return map.size();
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} finally {
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r.unlock();
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}
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}
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public boolean isEmpty() {
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r.lock();
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try {
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return map.isEmpty();
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} finally {
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r.unlock();
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}
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}
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public boolean containsKey(Object key) {
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r.lock();
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try {
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return map.containsKey(key);
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} finally {
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r.unlock();
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}
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}
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public boolean containsValue(Object value) {
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r.lock();
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try {
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return map.containsValue(value);
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} finally {
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r.unlock();
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}
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}
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public V remove(Object key) {
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w.lock();
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try {
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return map.remove(key);
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} finally {
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w.unlock();
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}
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}
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public void putAll(Map<? extends K, ? extends V> m) {
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w.lock();
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try {
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map.putAll(m);
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} finally {
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w.unlock();
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}
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}
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public void clear() {
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w.lock();
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try {
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map.clear();
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} finally {
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w.unlock();
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}
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}
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public Set<K> keySet() {
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r.lock();
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try {
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return map.keySet();
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} finally {
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r.unlock();
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}
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}
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public Collection<V> values() {
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r.lock();
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try {
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return map.values();
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} finally {
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r.unlock();
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}
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}
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public Set<Entry<K, V>> entrySet() {
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r.lock();
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try {
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return map.entrySet();
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} finally {
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r.unlock();
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}
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}
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}
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}

‎pom.xml‎

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<modules>
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<module>sort</module>
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<module>sort</module>
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<module>lru</module>
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</modules>
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<name>algorithm-study</name>
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<packaging>pom</packaging>

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