TCP Programming Example (non-multithreaded chat)

Server-side:

Package socket;

Import Java.io.BufferedReader;
Import java.io.IOException;
Import Java.io.InputStreamReader;
Import Java.io.OutputStreamWriter;
Import Java.io.PrintWriter;
Import java.net.*;

Import Java.util.Scanner;
		public class Chatserver {public static void main (string[] args) {ServerSocket server = null;
		Socket client = null;
		try {server = new ServerSocket (6666);
			} catch (IOException e) {System.out.println ("Connecting error!");
		System.exit (-1);
		} try {client = server.accept ();
			} catch (IOException e) {//TODO auto-generated catch block System.out.println ("Accept error!");
		System.exit (-1);
		} BufferedReader br = null;
		BufferedReader scan = null;
		PrintWriter pw = null;
		String line = null;
		String cmsg = null;
			try {br = new BufferedReader (New InputStreamReader (Client.getinputstream ()));
			Scan = new BufferedReader (new InputStreamReader (system.in));
PW = new PrintWriter (New OutputStreamWriter (Client.getoutputstream ()));			Cmsg = Br.readline (); while (! "
				Bye ". Equalsignorecase (cmsg)) {System.out.println (" Client: "+cmsg);
				line = Scan.readline ();
				Pw.println (line); 
				Pw.flush ();
			Cmsg = Br.readline ();
				} if ("Bye". Equalsignorecase (cmsg)) {pw.println ("Bye");
			Pw.flush ();
			} client.close ();
			Br.close ();
			Scan.close ();
		Pw.close ();
		} catch (IOException e) {//TODO auto-generated catch block E.printstacktrace ();
 }
	}

}

Client:

Package socket;

Import Java.io.BufferedReader;
Import java.io.IOException;
Import Java.io.InputStreamReader;
Import Java.io.OutputStreamWriter;
Import Java.io.PrintWriter;
Import Java.net.Socket;

Import java.net.UnknownHostException;
		public class ChatClient {public static void main (string[] args) {Socket client = null;
		try {client = new Socket ("127.0.0.1", 6666);
			} catch (Unknownhostexception e) {System.out.println ("Unknown Host");
		System.exit (-1);
		} catch (IOException e) {e.printstacktrace ();
			} try {BufferedReader br = new BufferedReader (New InputStreamReader (Client.getinputstream ()));
			BufferedReader scan = new BufferedReader (new InputStreamReader (system.in));
			PrintWriter pw = new PrintWriter (New OutputStreamWriter (Client.getoutputstream ()));
			String line = null;
			String SMSG = null; while (! "
				Bye ". Equalsignorecase (SMSG)) {line = Scan.readline ();
				Pw.println (line);
				Pw.flush ();
				SMSG = Br.readline (); System.out.println ("Server:" +smsg);
				} if ("Bye". Equalsignorecase (SMSG)) {pw.println ("Bye");
			Pw.flush ();
			} client.close ();
			Br.close ();
			  Scan.close ();
		Pw.close ();
		} catch (IOException e) {//TODO auto-generated catch block E.printstacktrace ();
 }
	}

}

Description

1. You need to start the server first, then start the client, and the client sends the message first.

2. Server cannot start the server again at startup.

3. Server.accept (), as well as the read operation of the stream, are blocked, and will wait if there is no client connection, or if the data is not being read into.

4. After using PrintWriter for print, you must flush (), otherwise you cannot read it. This is because the flush method is forced to flush the buffer. What is a buffer, is to create a space on your machine, this space allows you to put something in the first, For example, if you do not call flush, the contents of the println go into the buffer instead of OS.PRINTLN to the client or server side.

5. The program is synchronous, that is, only the client sends a message once, the server sends again, the client sends again ... Pending improvement.

6. The program opens two windows under the CMD to run the effect to be good.