写出一个缓存系统的伪代码001

/**
 * 写出一个缓存系统的伪代码*/
public class CacheDemo {

    private Map<String, Object> map = new HashMap<String, Object>();
    public static void main(String[] args) {
        // TODO Auto-generated method stub
    }    
    public synchronized Object getData(String key){ 
        Object value = map.get(key);
        if (value == null){
            return "aaa";//实现QueryDB()
        }
        return value;
    }
}