DefaultMBeanServerInterceptor.java 文件源码

private NotificationListener getListenerWrapper(NotificationListener l,
                                                ObjectName name,
                                                DynamicMBean mbean,
                                                boolean create) {
    Object resource = getResource(mbean);
    ListenerWrapper wrapper = new ListenerWrapper(l, name, resource);
    synchronized (listenerWrappers) {
        WeakReference<ListenerWrapper> ref = listenerWrappers.get(wrapper);
        if (ref != null) {
            NotificationListener existing = ref.get();
            if (existing != null)
                return existing;
        }
        if (create) {
            ref = new WeakReference<ListenerWrapper>(wrapper);
            listenerWrappers.put(wrapper, ref);
            return wrapper;
        } else
            return null;
    }
}