import java.util.LinkedHashMap;
import java.util.Map;
/**
* LRU (Least Recently Used)
*/
public class LRUCache<K, V> extends LinkedHashMap<K, V> {
/**
*
*/
private static final long serialVersionUID = 1L;
//缓存大小
private int cacheSize;
public LRUCache(int cacheSize) {
//第三个参数true是关键
super(10, 0.75f, true);
this.cacheSize = cacheSize;
}
/**
* 缓存是否已满
*/
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
boolean r = size() > cacheSize;
if(r){
System.out.println("清除缓存key："+eldest.getKey());
}
return r;
}
LRUCache<String, String> cache = new LRUCache<String, String>(5);
cache.put("1", "1");
cache.put("2", "2");
cache.put("3", "3");
cache.put("4", "4");
cache.put("5", "5");
System.out.println("初始：");
System.out.println(cache.keySet());
System.out.println("访问3：");
cache.get("3");
System.out.println(cache.keySet());
System.out.println("访问2：");
cache.get("2");
System.out.println(cache.keySet());
System.out.println("增加数据6,7：");
cache.put("6", "6");
cache.put("7", "7");
System.out.println(cache.keySet());
}
import java.util.Map;
/**
* LRU (Least Recently Used)
*/
public class LRUCache<K, V> extends LinkedHashMap<K, V> {
/**
*
*/
private static final long serialVersionUID = 1L;
//缓存大小
private int cacheSize;
public LRUCache(int cacheSize) {
//第三个参数true是关键
super(10, 0.75f, true);
this.cacheSize = cacheSize;
}
/**
* 缓存是否已满
*/
@Override
protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
boolean r = size() > cacheSize;
if(r){
System.out.println("清除缓存key："+eldest.getKey());
}
return r;
}
//测试
public static void main(String[] args) {LRUCache<String, String> cache = new LRUCache<String, String>(5);
cache.put("1", "1");
cache.put("2", "2");
cache.put("3", "3");
cache.put("4", "4");
cache.put("5", "5");
System.out.println("初始：");
System.out.println(cache.keySet());
System.out.println("访问3：");
cache.get("3");
System.out.println(cache.keySet());
System.out.println("访问2：");
cache.get("2");
System.out.println(cache.keySet());
System.out.println("增加数据6,7：");
cache.put("6", "6");
cache.put("7", "7");
System.out.println(cache.keySet());
}
}
运行结果如下：
初始化：
[1, 2, 3, 4, 5]
访问3：
[1, 2, 4, 5, 3]
访问2：
[1, 4, 5, 3, 2]
增加数据6,7：
清除缓存key：1
清除缓存key：4
[5, 3, 2, 6, 7]
