public Date getLastMessageAt() {
    AVIMMessage lastMessage = getLastMessage();
    if (null != lastMessage) {
      setLastMessageAt(new Date(lastMessage.getDeliveredAt()));
    }
    return lastMessageAt;
  }
public Date getLastMessageAt ( ) { AVIMMessage lastMessage = getLastMessage ( ) ; if ( null != lastMessage ) { setLastMessageAt ( new Date ( lastMessage . getDeliveredAt ( ) ) ) ; } return lastMessageAt ; }
获取最新一条消息的时间

@return