Sample TCP Client & Server in Java

Sample Client/Server Application written in Java. Very simple, and just illustrates a very simple TCP based Server/Client Application that sends messages back and forth via a port on the server. This was a project for my Graduate School Class but thought it shared some interesting principles and showed the fundamental intricacies of this concept.

D:\Users\Amit Apollo Barman.DS\Desktop\JavaTCP\clienttcp.java

1 import java.io.*;

2 import java.net.*;

3

4 class clienttcp

5 {

6 public static void main(String argv[]) throws Exception

7 {

8 String magicWord="not exit";

9 String magicWordServer;

10 String HostName;

11 int portnum=2222;

12

13 while(magicWord!="exit")

14 {

15 System.out.println("-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-");

16 BufferedReader inFromUser = new BufferedReader( new InputStreamReader(System.in));

17

18 System.out.println("Please enter the server name or host name:");

19 HostName = inFromUser.readLine();

20 System.out.println("Please enter your name to text to the server:");

21 magicWord = inFromUser.readLine();

22 System.out.println("Please enter the port:");

23

24 try

25 {

26 String portn = inFromUser.readLine();

27 portnum = Integer.parseInt(portn.trim());

28 Socket clientSocket = new Socket(HostName, portnum);

29 DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream());

30 BufferedReader inFromServer = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));

31 outToServer.writeBytes(magicWord + '\n');

32 magicWordServer = inFromServer.readLine();

33 System.out.println("FROM SERVER: " + magicWordServer);

34

35 System.out.println("-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-");

36 clientSocket.close();

37

38 }

39 catch (NumberFormatException nfe)

40 {

41 System.out.println("Number Format Exception: " + nfe.getMessage());

42 }

43

44

45 }

46 }

47 }

48

2/17/2010 clienttcp.java

D:/Users/…/clienttcp.html 1/1

D:\Users\Amit Apollo Barman.DS\Desktop\JavaTCP\servertcp.java

1 import java.io.*;

2 import java.net.*;

3

4 class servertcp

5 {

6 public static void main(String argv[]) throws Exception

7 {

8 String clientSentence;

9 String BackSentence="Not Exit";

10 int portnum=2222;

11

12 BufferedReader inFromUser = new BufferedReader( new InputStreamReader(System.in));

13

14 System.out.println("-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-");

15

16 System.out.println("Please enter a port to listen on:");

17

18 try

19 {

20 String portn = inFromUser.readLine();

21 portnum = Integer.parseInt(portn.trim());

22

23 ServerSocket welcomeSocket = new ServerSocket(portnum);

24 System.out.println("-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-");

25

26 System.out.println("Listening on Port:" + portnum + "...");

27

28 while(BackSentence!="exit")

29 {

30 Socket connectionSocket = welcomeSocket.accept();

31 BufferedReader inFromClient =

32 new BufferedReader(new InputStreamReader(connectionSocket.getInputStream()));

33 DataOutputStream outToClient = new DataOutputStream(connectionSocket.getOutputStream());

34 clientSentence = inFromClient.readLine();

35 System.out.println("Received from Client: " + clientSentence);

36 BackSentence = clientSentence + '\n';

37 outToClient.writeBytes(BackSentence);

38 }

39

40 }

41 catch (NumberFormatException nfe)

42 {

43 System.out.println("Number Format Exception: " + nfe.getMessage());

44 }

45

46

47 System.out.println("-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-");

48

49 }

50 }

51

2/17/2010 servertcp.java

D:/Users/…/servertcp.html 1/1