在Java中访问每个父类的子类(Accessing every child class of parent class in Java)

 实际上， 在应用程序级别寻找东西是唯一的方法 。 以下是一些问题： 
 
 
 
 当您send数据时，即使它离开您的内核，在TCP收到有关它的ACK之前，它也不会完成。 API不会向您提供此信息 。 
 
 
 您的应用程序收到ACK的事实可能意味着： 
 
  
 
   
 远程内核（ 不是应用程序 ）接收数据。 没有人知道远程进程是否称为recv 。 也许它在有机会重新开始之前就崩溃了。 
 
   
 一些代理（许多廉价设备这样做）正在与您交谈，并且使用与真实接收器的单独连接。 您收到了ACK但是您不知道远程系统是否有它。 如果远程系统有它，请阅读上面的子弹。 
 
  
 
 
 结论是： 
 
 
 
 您无权访问TCP ACK 
 
 
 即使你会对他们有所帮助，他们也会毫无用处 
 
 
 所以你需要一个应用程序级别的ACK，但当然没有重传 。 ACK应该只告诉您“我收到并处理了您的数据”。 
 
 编辑 
 
 我看到你坚持你的想法。 如一些Linux手册页所述，去寻找SIOCOUTQ 。 当然它只是Linux，但看看它是否能满足您的需求。 

Actually acking stuff at application level is the only way. Here are a few issues:
 
 
 
When you send data, even if it leaves your kernel it's not done until your TCP receives an ACK about it. The API doesn't provide you with this information.
 
 
The fact that your application received an ACK can mean:
 
  
 
   
The remote kernel (not the application) received the data. There's no telling if the remote process called recv. Maybe it crashes before getting a chance to recv.
 
   
Some proxy (MANY cheap devices do this) is talking to you and is using a separate connection with the true receiver. You received the ACK but you don't know if the remote system has it. And if the remote system has it, read the bullet above.
 
  
 
 
In conclusion:
 
 
 
You don't have access to TCP ACKs
 
 
Even if you would have acess to them, they would be useless
 
 
So you need an application-level ACK, but of course without retransmissions. The ACK should merely tell you "I received and processed your data".
 
EDIT
 
I see you persevere in your idea. Go look for SIOCOUTQ as described in a few Linux manual pages. Of course it's Linux-onlye, but see if it does what you need.