Cache LRU : Cache « Development Class « Java

1. Java
2. Development Class
3. Cache

Cache LRU

 
/*
 * Copyright (c) 2009, TamaCat.org
 * All rights reserved.
 */
//package org.tamacat.util;

import java.util.ArrayList;
import java.util.Collection;
import java.util.LinkedHashMap;
import java.util.Set;

public class CacheLRU<K,V> {

  private int maxSize;
  private LinkedHashMap<K, V> cache;
  private ArrayList<K> used;
  
  public CacheLRU(int maxSize) {
    this.maxSize = maxSize;
    this.cache = new LinkedHashMap<K,V>(maxSize);
    this.used = new ArrayList<K>(maxSize);
  }
  
  public CacheLRU() {
    this(10);
  }
  
  public synchronized V get(K key) {
    updateUsed(key);
    return cache.get(key);
  }
  
  public synchronized V put(K key, V value) {
    if (cache.size() >= maxSize && used.size() > 0) {
      cache.remove(used.get(0));
      used.remove(0);
    }
    updateUsed(key);
    return cache.put(key, value);
  }
  
  private void updateUsed(K key) {
    used.remove(key);
    used.add(key);    
  }
  
  public synchronized int size() {
    return cache.size();
  }
  
  public synchronized V remove(K key) {
    used.remove(key);
    return cache.remove(key);
  }
  
  public synchronized void clear() {
    cache.clear();
    used.clear();
  }
  
  public Set<K> keySet() {
    return cache.keySet();
  }
  
  public Collection<V> values() {
    return cache.values();
  }
  
  @Override
  public String toString() {
    return getClass().getName() + "@" + hashCode() + "" + cache.toString();
  }
}

------------

/*
 * Copyright (c) 2009, TamaCat.org
 * All rights reserved.
 */
package org.tamacat.util;

import static org.junit.Assert.*;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class CacheLRUTest {

  @Before
  public void setUp() throws Exception {
  }

  @After
  public void tearDown() throws Exception {
  }

  @Test
  public void testGet() {
    int maxSize = 3;
    CacheLRU<String,String> cache = new CacheLRU<String,String>(maxSize);
    cache.put("1", "1");
    cache.put("2", "2");
    cache.put("3", "3");
    assertEquals(maxSize, cache.size());
    //cache.get("2");
    //cache.get("1");
    //System.out.println(cache.toString());
    cache.put("4", "4");
    cache.put("5", "5");
    //System.out.println(cache.toString());
    assertEquals(maxSize, cache.size());
  }

}

   
  

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