KprAlamBizPlugin/src/main/java/com/shkpr/service/alambizplugin/dbdao/DBMgrProxy.java

package com.shkpr.service.alambizplugin.dbdao;

import com.shkpr.service.alambizplugin.SpringContextUtil;
import com.shkpr.service.alambizplugin.dbdao.services.intef.*;

import java.util.HashSet;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;

public class DBMgrProxy {
    final static Set<Class<?>> INIT_CLASS = new HashSet<Class<?>>(){{
        add(UserDBService.class);
    }};
    private Map<Class<?>, Object> mapClass2Instance = new ConcurrentHashMap<>();

    private static volatile DBMgrProxy msInstance = null;
    public static DBMgrProxy getInstance(){
        if (msInstance == null){
            synchronized (DBMgrProxy.class){
                if (msInstance == null)
                    msInstance = new DBMgrProxy();
            }
        }
        return msInstance;
    }

    private DBMgrProxy() {
    }

    public void init(){
        for (Class<?> item:INIT_CLASS)
            mapClass2Instance.put(item, SpringContextUtil.getBean(item));
    }

    public <T> T applyXXXApi(Class<T> className){
        T cls = (T)mapClass2Instance.get(className);
        if (cls == null){
            synchronized (this){
                cls = (T)mapClass2Instance.get(className);
                if (cls == null){
                    cls = SpringContextUtil.getBean(className);
                    mapClass2Instance.put(className, cls);
                }
            }
        }
        return cls;
    }
}