Listener<FriendMessageEvent> subscribe;

@Override
public void start() {
    subscribe = GlobalEventChannel.INSTANCE.subscribe(FriendMessageEvent.class, event -> {
        MessageChain message = event.getMessage();
        message.forEach(m -> {
            if (m instanceof MessageContent) {
                String str = m.contentToString();
                event.getSubject().sendMessage(str);
            }
        });
        return ListeningStatus.LISTENING;
    });
}

@Override
public void stop() {
    System.out.println("结果==》" + subscribe.complete());
}

%(#55d929)[如果 handler 返回 ListeningStatus.STOPPED 监听器将被停止.
也可以通过 subscribe 返回值 Listener 的 Listener.complete]