如何实现单例 - 在weblogic中

public class Singleton {
    private static Singleton instance;

    private Singleton() {
        // 私有构造函数，防止外部实例化
    }

    public static Singleton getInstance() {
        if (instance == null) {
            instance = new Singleton();
        }
        return instance;
    }
}

import javax.ejb.Singleton;

@Singleton
public class MySingleton {
    // 实现业务逻辑
}

import weblogic.utils.singleton.SingletonService;

public class MySingletonService implements SingletonService {
    private static MySingletonService instance;

    private MySingletonService() {
        // 私有构造函数，防止外部实例化
    }

    public static MySingletonService getInstance() {
        if (instance == null) {
            instance = new MySingletonService();
        }
        return instance;
    }

    @Override
    public Object getInstance(Object[] args) {
        return getInstance();
    }

    @Override
    public void resetInstance(Object instance) {
        // 重置实例
    }
}

<wls:singleton-service-descriptor xmlns:wls="http://www.bea.com/ns/weblogic/90"
                                  class-name="MySingletonService">
    <wls:name>MySingletonService</wls:name>
</wls:singleton-service-descriptor>

MySingletonService instance = (MySingletonService) weblogic.utils.singleton.SingletonServiceManager.getInstance("MySingletonService");