java线程套接字：哪个线程接收数据包？

Question

I am working on a p2p project. This project is supposed to be able to send and receive binary files and text messages concurrently. I have two separate threads for receiving file and messages. The problem is how to specify which thread should receive packet that is coming. now is it better to have just one thread for both operations? If yes how can i recognize the received packet type?

Answer 1

You need one thread to manage the socket, and one each for chat and file transfer. The thread manager decided who gets the packet, based on whatever protocol you devise to distinguish the packets.

Answer 2

You will need a custom packet to determine what kind 'packet' it is. For example, a serialized class that implements an interface that knows what type of packet it is. Rough structure example.

Packet implements Serializable{
 enum type;
 Object data

 public setdata
 public getdata
 ...
 ...
}

There is two ways to do this.

1 - Do what you suggested. Use one thread to handle both files and messages depending on the type of packet.

2 - Use two seperate threads. But create a handler to deliver the packet to give to the proper thread depending on the packet type.

edit:

Oh as Jim mentioned, you'll need another thread to manage the socket.

Answer 3

I have two separate threads for receiving file and messages.

Why?

The problem is how to specify which thread should receive packet that is coming.

Your first problem is that there are no 'packets' in the TCP API. It provides a bytestream. Any packetising is entirely up to you at both ends.

Your second problem is that the thread that entered read() first will get the next data that arrives (or has already arrived).

now is it better to have just one thread for both operations?

Definitely.

If yes how can I recognize the received packet type?

As I said above, if there are to be 'packets' in this application, you will have to define them. That will almost certainly include a length word and it may as well include a type word as well.