利用java内部静态类实现懒汉式单例

/**
 * @Description： 利用键值模式控制service
 * @Author: zhanglifeng
 * @Date: 2019年 04月 28日 14:41
 **/
public class ServiceManagerSingleton {
    private static final Logger logger = LoggerFactory.getLogger(ServiceManagerSingleton.class);

    private static Map<String, IChannelService> serviceMap;

    @Resource(type = com.***.***.service.impl.CCBServiceImpl.class)
    private IChannelService ccbService;

    private static class SingletonHolder {
        //由JVM保证只初始化一次
        private static ServiceManagerSingleton instance = new ServiceManagerSingleton();
    }

    //初始化需要使用的service
    private ServiceManagerSingleton() {
        serviceMap = Maps.newHashMap();
        serviceMap.put(CommonConst.MQ_KEY_WXZX,ccbService);
    }

    public static ServiceManagerSingleton getInstance() {
        return SingletonHolder.instance;
    }
}