DaoCache.java

/*
 * Copyright (c) www.bugull.com
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.tooan.ynpay.third.mongodb.cache;

import net.tooan.ynpay.third.mongodb.mapper.InternalDao;

import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;

/**
 * Cache(Map) contains dao instance.
 *
 * @author Frank Wen(xbwen@hotmail.com)
 */
@SuppressWarnings("unchecked")
public class DaoCache {

    private static DaoCache instance = new DaoCache();

    private final ConcurrentMap<String, InternalDao<?>> cache = new ConcurrentHashMap<String, InternalDao<?>>();

    private DaoCache() {

    }

    public static DaoCache getInstance() {
        return instance;
    }

    public <T> InternalDao<T> get(Class<T> clazz) {
        String name = clazz.getName();
        InternalDao<?> dao = cache.get(name);
        if (dao != null) {
            return (InternalDao<T>) dao;
        }

        dao = new InternalDao<T>(clazz);
        InternalDao<?> temp = cache.putIfAbsent(name, dao);
        if (temp != null) {
            return (InternalDao<T>) temp;
        } else {
            return (InternalDao<T>) dao;
        }
    }

}