单例模式结合享元模式的使用

public class DataCenter {

    private String name;
    
    public DataCenter(String name)
    {
        this.name = name;
    }
    
    public String getName()
    {
        return this.name;
    }
}

import java.util.HashMap;
import java.util.Map;


public class DataCenterFactory {
    
    /**
     * 数据中心缓存
     */
    private Map<String,DataCenter> dataCenterCache = new HashMap<String,DataCenter>();
    
    /**
     * 私有构造器
     */
    private DataCenterFactory()    {    }
    
    /**
     * 由静态内部类维护单例
     * @author admin
     *
     */
    private static class SingletonHolder
    {
        private static DataCenterFactory instance = new DataCenterFactory();
    }
    
    public static DataCenterFactory getInstance()
    {
        return SingletonHolder.instance;
    }

    /**
     * 对外提供数据中心缓存
     * @param name
     * @return
     */
    public DataCenter getDataCenter(String name) 
    {
        if(null == dataCenterCache.get(name))
        {
            dataCenterCache.put(name,new DataCenter(name));
        }
        return dataCenterCache.get(name);
    }
    
}