java Map实现的cache manager

一个模仿memcached的JAVA虚拟缓存工具，可以缓存java对象；

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.concurrent.ConcurrentHashMap;
import java.util.Map;

/**
* java Map cache manager 改进版
* 特点：无线程，取出时判断过期，系列化实现的深度克隆，覆盖原则
* 问题: 线程安全，克隆带来的时效损耗
* @author frank
*
*/
public class VirtualCache{

/**
* 开发模式
*/
private boolean isdev = false;

private static String ERROR_SET = "VirtualCache缓存数据异常:key=";

private static String ERROR_GET= "VirtualCache取出数据异常:key=";

/**
* 虚拟缓存
*/
private Map<String,Object> cache = new ConcurrentHashMap<String, Object>();

/**
* 过期时间
*/
private Map<String,Long> tasks = new ConcurrentHashMap<String,Long>();

public VirtualCache(boolean isdev){
this.isdev = isdev;
}

public VirtualCache(){

}

/**
* 深度克隆
*/
private Object clone(String key,Object obj,boolean isSet){
if(obj == null)
return null;
ByteArrayOutputStream bo = null;
ObjectOutputStream oo = null;
ByteArrayInputStream bi = null;
ObjectInputStream oi = null;
Object value = null;
try {
bo=new ByteArrayOutputStream();
oo = new ObjectOutputStream(bo);
oo.writeObject(obj);
bi=new ByteArrayInputStream(bo.toByteArray());
oi=new ObjectInputStream(bi);
value = oi.readObject();
} catch (Exception e) {
this.printError(e, key,isSet);
} finally{
if(oo != null)
try {
oo.close();
} catch (Exception e) {
this.printError(e, key,isSet);
}
if(oi != null)
try {
oi.close();
} catch (Exception e) {
this.printError(e, key,isSet);
}
}
return value;
}

/**
* 日志输出
*/
private void printError(Exception e,String key,boolean isSet){
if(isSet)
System.err.println(ERROR_SET + key);
else
System.err.println(ERROR_GET + key);
if(this.isdev)
e.printStackTrace();
}

/**
* 存入缓存
*/
public void set(String key,Object value,long timeout){
        this.delete(key);
this.cache.put(key, this.clone(key,value,true));
if(timeout > 0l)
this.tasks.put(key,timeout*1000l + System.currentTimeMillis());
}

/**
* 获取缓存
*/
public Object get(String key){
Long timeout = this.tasks.get(key);
if(timeout != null && timeout <= System.currentTimeMillis())
this.delete(key);
return this.clone(key,this.cache.get(key),false);
}

/**
* 删除缓存
*/
public void delete(String key){
this.cache.remove(key);
this.tasks.remove(key);
}

}