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import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
public class SimpleCache<K,V> {
private final Lock lock=new ReentrantLock();
private final int maxCapacity; //最大存储能力
private final Map<K,V> eden; //边界缓存or临时缓存
private final Map<K,V> longterm; //长久缓存 当 对象不使用时会被虚拟机gc()的
public SimpleCache( int maxCapacity){
this. maxCapacity=maxCapacity;
this. eden= new ConcurrentHashMap<K, V>(maxCapacity);
this. longterm= new WeakHashMap<K,V>(maxCapacity);
}
//清空缓存中某个key和value先清空缓存中的值然后清除固定缓存中的值
public void deleteKey(K k){
if( null!= this.get(k)){
this. doDel(k);
}
}
public void doDel (K k){
this. eden.remove(k);
if( null!= this. longterm.get(k)){
this. longterm.remove(k);
}
}
//根据某Key获取相对应的值，先从临时缓存中查找，若不存在则去固定缓存中查找，若存在则将查到的值放入到临时缓存中
public V get(K k){
V v=this.eden.get(k);
if(v==null){
lock.lock();
try{
v= this. longterm.get(k);
} finally{
lock.unlock();
}
if(v!= null){
this. eden.put(k, v);
}
}
return v;
}
//将值放入临时缓存中，若临时缓存溢出，则将临时缓存中全部取出放入固定缓存中，同时清空临时缓存，并将新加入的值放入临时缓存中
public void put(K k,V v){
if(this.eden.size()>=maxCapacity){
lock.lock();
try{
this. longterm.putAll( this. eden);
} finally{
lock.unlock();
}
this. eden.clear();
}
this.eden.put(k, v);
}
}
///////////////////////////////////////////////////////////////////////////////////////////////
实现类
public class MyCache extends SimpleCache<String, Object> {
public MyCache( int maxCapacity) {
super(maxCapacity);
}
public static void main(String[] args) {
MyCache myCache= new MyCache(10);
myCache.put( "1", 123);
System. out.print(myCache.get( "1"));
myCache.deleteKey( "1");
System. out.println(myCache.get( "1"));
}
}
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