使用Swing的Java聊天应用程序（概念性）

Question

I want to write a chat application in Java using Swing as an interface.

I have come up with an idea (with the help of MadProgrammer ), but I am not sure whether it is the best way to go about this.

There are two Blockinqueue queues in the main Thread, one for incoming messages and one for outgoing messages.

There are four threads, two for outgoing and two for incoming messages, one each to handle the GUI and the socket.

Threads for outgoing messages:

1. ActionListener (Swing) : Is triggered when user clicks "send" in GUI. The thread adds the new message to the Outgoing Queue and triggers notifyAll() on it.
2. socketOutgoing : Has access to socket. Sleeps, with wait() on Outgoing Queue, until it is notified. Sends new messages in Outgoing Queue through socket, then goes back to sleep again.

Threads for incoming messages:

1. socketIncoming: Has access to socket. Checks continuously for new message in socket (how?). When there is a new message, adds it to the Outgoing Queue and triggers notifyAll() on it.
2. Swingworker displayIncoming : Sleeps, with wait() on Incoming Queue, until it is notified. Displays new messages in GUI, then goes back to sleep again.

While this would theoretically work, it seems a bit messy (and unreliable) to have four threads for this.

Is there a more practical solution?

Note to future readers: My description of socketIncoming was misguided: It is not possible to "check continuously for new message in socket".

When you call ObjectInputStream#readObject() , and there is no new message, it simply waits, or "blocks", until a new messages arrives. There is no way to check beforehand whether a new message has arrived. See this question .

Answer 1

If I was thinking about doing something like I would probably set up two queues, an outgoing and incoming queue. These would be used to "stage" messages.

The idea being that outgoing messages would be placed into the outgoing queue and when Thread was able to, it would pop off the next message and send it. When the queue was empty, it would simply "wait" until a new message become available.

The concept would work in reverse for the incoming queue. The Thread would read a message and push it onto the incoming queue.

Some other process (possibly a SwingWorker ) would be monitoring the queue and pop the next message of it and re-sync it with the GUI.

You might find Concurrency in Swing of some use.

How the underlying protocol actually worked would dictate a lot more of the details though

Answer 2

for a simple chat application you shall have two parts

1. Client part
2. Server part.

Now, you have to decide which protocol you want to use for your communication [Tcp] or [Udp]. Though your message transmission should be reliable so you have to use java Tcp ServerSocket. your server will be multi-threaded means for each client connect with server will have separate thread to handle all message communication from that client.

For Client side, it will have GUI componenet and one dedicated thread to receive message from server. when you want to send message to any user, just pass the message and send through client socket.